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Hearn SL, Stino AM, Howard IM, Malhotra G, Robinson L. Serial electrodiagnostic testing: Utility and indications in adult neurological disorders. Muscle Nerve 2024; 69:670-681. [PMID: 38549195 DOI: 10.1002/mus.28083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Accepted: 03/07/2024] [Indexed: 05/08/2024]
Abstract
Although existing guidelines address electrodiagnostic (EDX) testing in identifying neuromuscular conditions, guidance regarding the uses and limitations of serial (or repeat) EDX testing is limited. By assessing neurophysiological change longitudinally across time, serial electrodiagnosis can clarify a diagnosis and potentially provide valuable prognostic information. This monograph presents four broad indications for serial electrodiagnosis in adult peripheral neurological disorders. First, where clinical change has raised suspicion for a new or ongoing lesion, EDX reassessment for spatial spread of abnormality, involvement of previously normal muscle or nerve, and/or evolving pathophysiology can clarify a diagnosis. Second, where diagnosis of a progressive neuromuscular condition is uncertain, electrophysiological data from a second time point can confirm or refute suspicion. Third, to establish prognosis after a static nerve injury, a repeat study can assess the presence and extent of reinnervation. Finally, faced with a limited initial study (as when complicated by patient or environmental factors), a repeat EDX study can supplement missing or limited data to provide needed clarity. Repeat EDX studies carry certain limitations, however, such as with prognostication in the setting of remote or chronic lesions, sensory predominant fascicular injury, or mild axonal injury. Nevertheless, serial electrodiagnosis remains a valuable and underused tool in the diagnostic and prognostic evaluation of neuromuscular conditions.
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Affiliation(s)
- Sandra L Hearn
- Department of Physical Medicine and Rehabilitation, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Amro Maher Stino
- Division of Neuromuscular Medicine, Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Ileana M Howard
- Department of Rehabilitation Medicine, University of Washington, Washington, USA
| | - Gautam Malhotra
- Altair Health, Morristown, New Jersey, USA
- Department of Physical Medicine and Rehabilitation, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Lawrence Robinson
- Division of Physical Medicine and Rehabilitation, University of Toronto, Toronto, Ontario, Canada
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2
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Guo Y, Jones EJ, Škarabot J, Inns TB, Phillips BE, Atherton PJ, Piasecki M. Common synaptic inputs and persistent inward currents of vastus lateralis motor units are reduced in older male adults. GeroScience 2024; 46:3249-3261. [PMID: 38238546 PMCID: PMC11009172 DOI: 10.1007/s11357-024-01063-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 01/02/2024] [Indexed: 04/13/2024] Open
Abstract
Although muscle atrophy may partially account for age-related strength decline, it is further influenced by alterations of neural input to muscle. Persistent inward currents (PIC) and the level of common synaptic inputs to motoneurons influence neuromuscular function. However, these have not yet been described in the aged human quadriceps. High-density surface electromyography (HDsEMG) signals were collected from the vastus lateralis of 15 young (mean ± SD, 23 ± 5 y) and 15 older (67 ± 9 y) men during submaximal sustained and 20-s ramped contractions. HDsEMG signals were decomposed to identify individual motor unit discharges, from which PIC amplitude and intramuscular coherence were estimated. Older participants produced significantly lower knee extensor torque (p < 0.001) and poorer force tracking ability (p < 0.001) than young. Older participants also had lower PIC amplitude (p = 0.001) and coherence estimates in the alpha frequency band (p < 0.001) during ramp contractions when compared to young. Persistent inward currents and common synaptic inputs are lower in the vastus lateralis of older males when compared to young. These data highlight altered neural input to the clinically and functionally important quadriceps, further underpinning age-related loss of function which may occur independently of the loss of muscle mass.
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Affiliation(s)
- Yuxiao Guo
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK
| | - Eleanor J Jones
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK
| | - Jakob Škarabot
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Thomas B Inns
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK
| | - Bethan E Phillips
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK
| | - Philip J Atherton
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK
| | - Mathew Piasecki
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research &, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Royal Derby Hospital Centre (Room 3011), Derby, DE22 3DT, UK.
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3
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Esen O, Bailey SJ, Stashuk DW, Howatson G, Goodall S. Influence of nitrate supplementation on motor unit activity during recovery following a sustained ischemic contraction in recreationally active young males. Eur J Nutr 2024:10.1007/s00394-024-03440-9. [PMID: 38809323 DOI: 10.1007/s00394-024-03440-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 05/21/2024] [Indexed: 05/30/2024]
Abstract
PURPOSE Dietary nitrate (NO3-) supplementation enhances muscle blood flow and metabolic efficiency in hypoxia, however, its efficacy on neuromuscular function and specifically, the effect on motor unit (MU) activity is less clear. We investigated whether NO3- supplementation affected MU activity following a 3 min sustained ischemic contraction and whether this is influenced by blood flow restriction (BFR) during the recovery period. METHOD In a randomized, double-blinded, cross-over design, 14 males (mean ± SD, 25 ± 6 years) completed two trials following 5 days of supplementation with NO3--rich (NIT) or NO3--depleted (PLA) beetroot juice to modify plasma nitrite (NO2-) concentration (482 ± 92 vs. 198 ± 48 nmol·L-1, p < 0.001). Intramuscular electromyography was used to assess MU potential (MUP) size (duration and area) and mean firing rates (MUFR) during a 3 min submaximal (25% MVC) isometric contraction with BFR. These variables were also assessed during a 90 s recovery period with the first half completed with, and the second half completed without, BFR. RESULTS The change in MUP area and MUFR, did not differ between conditions (all p > 0.05), but NIT elicited a reduction in MUP recovery time during brief isometric contractions (p < 0.001), and during recoveries with (p = 0.002) and without (p = 0.012) BFR. CONCLUSION These novel observations improve understanding of the effects of NO3- on the recovery of neuromuscular function post-exercise and might have implications for recovery of muscle contractile function. TRIAL REGISTRATION The study was registered on clinicaltrials.gov with ID of NCT05993715 on August 08, 2023.
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Affiliation(s)
- Ozcan Esen
- Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-Upon-Tyne, NE1 8ST, UK.
- Department of Health Professions, Manchester Metropolitan University, Manchester, UK.
| | - Stephen J Bailey
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Daniel W Stashuk
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON, Canada
| | - Glyn Howatson
- Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-Upon-Tyne, NE1 8ST, UK
- Water Research Group, North West University, Potchefstroom, South Africa
| | - Stuart Goodall
- Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-Upon-Tyne, NE1 8ST, UK
- Physical Activity, Sport and Recreation Research Focus Area, Faculty of Health Sciences, North-West University, Potchefstroom, South Africa
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4
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Kemfack AM, Hernandez-Morato I, Moayedi Y, Pitman MJ. Transcriptome Analysis of Left Versus Right Intrinsic Laryngeal Muscles Associated with Innervation. Laryngoscope 2024. [PMID: 38721727 DOI: 10.1002/lary.31487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 04/18/2024] [Accepted: 04/24/2024] [Indexed: 05/21/2024]
Abstract
OBJECTIVES/HYPOTHESIS Recurrent laryngeal nerve injury diagnosed as idiopathic or due to short-term surgery-related intubation exhibits a higher incidence of left-sided paralysis. While this is often attributed to nerve length, it is hypothesized there are asymmetric differences in the expression of genes related to neuromuscular function that may impact reinnervation and contribute to this laterality phenomenon. To test this hypothesis, this study analyzes the transcriptome profiles of the intrinsic laryngeal muscles (ILMs), comparing gene expression in the left versus right, with particular attention to genetic pathways associated with neuromuscular function. STUDY DESIGN Laboratory experiment. METHODS RNA was extracted from the left and right sides of the rat posterior cricoarytenoid (PCA), lateral thyroarytenoid (LTA), and medial thyroarytenoid (MTA), respectively. After high-throughput RNA-Sequencing, 88 samples were organized into 12 datasets according to their age (P15/adult), sex (male/female), and muscle type (PCA/LTA/MTA). A comprehensive bioinformatics analysis was conducted to compare the left-right ILMs across different conditions. RESULTS A total of 774 differentially expressed genes were identified across the 12 experimental groups, revealing age, sex, and muscle-specific differences between the left versus right ILMs. Enrichment analysis of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways implicated several genes with a left-right laryngeal muscle asymmetry. These genes are associated with neuronal and muscular physiology, immune/inflammatory response, and hormone control. CONCLUSION Bioinformatics analysis confirmed divergent transcriptome profiles between the left-right ILMs. This preliminary study identifies putative gene targets that will characterize ILM laterality. LEVEL OF EVIDENCE N/A Laryngoscope, 2024.
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Affiliation(s)
- Angela M Kemfack
- The Center for Voice and Swallowing, Department of Otolaryngology-Head & Neck Surgery, Columbia University Irving Medical Center, New York, New York, U.S.A
| | - Ignacio Hernandez-Morato
- The Center for Voice and Swallowing, Department of Otolaryngology-Head & Neck Surgery, Columbia University Irving Medical Center, New York, New York, U.S.A
- Department of Anatomy and Embryology, School of Medicine, Complutense University of Madrid, Madrid, Spain
| | - Yalda Moayedi
- The Center for Voice and Swallowing, Department of Otolaryngology-Head & Neck Surgery, Columbia University Irving Medical Center, New York, New York, U.S.A
- Department of Neurology, Columbia University Irving Medical Center, New York, New York, U.S.A
- Pain Research Center, New York University College of Dentistry, New York University, New York, New York, U.S.A
| | - Michael J Pitman
- The Center for Voice and Swallowing, Department of Otolaryngology-Head & Neck Surgery, Columbia University Irving Medical Center, New York, New York, U.S.A
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5
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Hirono T, Takeda R, Nishikawa T, Watanabe K. Prediction of 1-year change in knee extension strength by neuromuscular properties in older adults. GeroScience 2024; 46:2561-2569. [PMID: 38093024 PMCID: PMC10828468 DOI: 10.1007/s11357-023-01035-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 12/04/2023] [Indexed: 02/01/2024] Open
Abstract
Improving muscle strength and preventing muscle weakness are important for older adults. The change in strength can be effectively explained by skeletal muscle mass and neural factors. Neural factors are important for older adults because the variation of neural components is greater in older than in young adults, and any decline in strength cannot solely be explained by a decrease in skeletal muscle mass. The purpose of the present study was to investigate whether skeletal muscle mass or motor unit firing properties could explain the change in muscle strength after 1 year. Thirty-eight older adults (75.0 ± 4.7 years, 156.6 ± 7.7 cm, 55.5 ± 9.4 kg, 26 women) performed maximum voluntary knee extension and their skeletal muscle mass was measured using a bioimpedance device. During a submaximal contraction task, high-density surface electromyography was recorded and the signals were decomposed into individual motor unit firing. As an index of motor unit firing properties, the slope and y-intercept (MU intercept) were calculated from the regression line between recruitment thresholds and firing rates in each participant. After 1 year, their maximum knee extension torque was evaluated again. A stepwise multiple regression linear model with sex and age as covariates indicated that MU intercept was a significant explanation with a negative association for the 1-year change in muscle strength (β = - 0.493, p = 0.004), but not skeletal muscle mass (p = 0.364). The results suggest that neural components might be predictors of increasing and decreasing muscle strength rather than skeletal muscle mass.
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Affiliation(s)
- Tetsuya Hirono
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101 Tokodachi, Kaizu-Cho, Toyota, Aichi, Japan.
- Human Health Sciences, Graduate School of Medicine, Kyoto University, 53 Kawahara-Cho, Shogoin, Sakyo-Ku, Kyoto, Japan.
| | - Ryosuke Takeda
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101 Tokodachi, Kaizu-Cho, Toyota, Aichi, Japan
| | - Taichi Nishikawa
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101 Tokodachi, Kaizu-Cho, Toyota, Aichi, Japan
- Graduate School of Health and Sport Sciences, Chukyo University, 101 Tokodachi, Kaizu-Cho, Toyota, Aichi, Japan
| | - Kohei Watanabe
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101 Tokodachi, Kaizu-Cho, Toyota, Aichi, Japan
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6
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Dericioglu D, Methven L, Clegg ME. Understanding age-related changes: exploring the interplay of protein intake, physical activity and appetite in the ageing population. Proc Nutr Soc 2024:1-13. [PMID: 38557431 DOI: 10.1017/s0029665124002192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Globally, we are currently facing a rapid demographic shift leading to an increase in the proportion of older adults within the population. This raises concerns about the potential increase in age-related diseases and their impact on our ability to provide adequate health and end-of-life care. To apply appropriate interventions, understanding the changes that happen with ageing becomes essential. Ageing is often accompanied by a decrease in appetite and physical activity, which may lead to malnutrition, resulting in decreased muscle mass, physical capabilities and independence. To preserve muscle mass, older adults are advised to increase protein intake and physical activity. However, protein's high satiating effect may cause reduced energy intake. Physical activity is also advised to maintain or enhance older adult's appetite. This review paper aims to discuss appetite-related changes that occur with ageing and their consequences. In particular, it will focus on investigating the relationship between protein intake and physical activity and their impact on appetite and energy intake in the ageing population. Recent studies suggest that physical activity might contribute to maintaining or enhancing appetite in older adults. Nevertheless, establishing a definitive consensus on the satiating effect of protein in ageing remains a work in progress, despite some promising results in the existing literature.
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Affiliation(s)
- Dilara Dericioglu
- Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences, University of Reading, Whiteknights, ReadingRG6 6DZ, UK
- Institute of Food, Nutrition and Health, University of Reading, Whiteknights, Reading RG6 6EU, UK
| | - Lisa Methven
- Institute of Food, Nutrition and Health, University of Reading, Whiteknights, Reading RG6 6EU, UK
- Food Research Group, Department of Food and Nutritional Sciences, University of Reading,Whiteknights, Reading RG6 6DZ, UK
| | - Miriam E Clegg
- Hugh Sinclair Unit of Human Nutrition, Department of Food and Nutritional Sciences, University of Reading, Whiteknights, ReadingRG6 6DZ, UK
- Institute of Food, Nutrition and Health, University of Reading, Whiteknights, Reading RG6 6EU, UK
- School of Food and Nutritional Sciences, University College Cork, Cork, Ireland
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7
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Davidson S, Learman K, Zimmerman E, Rosenfeldt AB, Koop M, Alberts JL. Older adults are impaired in the release of grip force during a force tracking task. Exp Brain Res 2024; 242:665-674. [PMID: 38246931 PMCID: PMC10894767 DOI: 10.1007/s00221-023-06770-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 12/17/2023] [Indexed: 01/23/2024]
Abstract
Age-related changes in force generation have been implicated in declines in older adult manual dexterity. While force generation is a critical aspect of the successful manipulation of objects, the controlled release of force represents the final component of dexterous activities. The impact of advancing age on the release of grip force has received relatively little investigation despite its importance in dexterity. The primary aim of this project was to determine the effects of age on the control of force release during a precision grip tracking task. Young adults (N = 10, 18-28 years) and older adults (N = 10, 57-77 years) completed a ramp-hold-release (0-35% of maximum grip force) force tracking task with their dominant hand. Compared to young adults, older adults were disproportionately less accurate (i.e., less time within target range) and had more error (i.e., greater relative root mean squared error) in the release of force, compared to generation of grip force. There was a significant difference between groups in two-point discrimination of the thumb, which was moderately correlated to force control across all phases of the task. The decline in force release performance associated with advanced age may be a result of sensory deficits and changes in central nervous system circuitry.
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Affiliation(s)
- Sara Davidson
- Department of Biomedical Engineering, Cleveland Clinic, 9500 Euclid Avenue, ND-20, Cleveland, OH, 44195, USA
- Youngstown State University, Youngstown, OH, USA
| | | | - Eric Zimmerman
- Department of Biomedical Engineering, Cleveland Clinic, 9500 Euclid Avenue, ND-20, Cleveland, OH, 44195, USA
| | | | - Mandy Koop
- Department of Biomedical Engineering, Cleveland Clinic, 9500 Euclid Avenue, ND-20, Cleveland, OH, 44195, USA
- Cleveland Clinic, Center for Neurologic Restoration, Cleveland, OH, USA
| | - Jay L Alberts
- Department of Biomedical Engineering, Cleveland Clinic, 9500 Euclid Avenue, ND-20, Cleveland, OH, 44195, USA.
- Cleveland Clinic, Center for Neurologic Restoration, Cleveland, OH, USA.
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Granic A, Suetterlin K, Shavlakadze T, Grounds M, Sayer A. Hallmarks of ageing in human skeletal muscle and implications for understanding the pathophysiology of sarcopenia in women and men. Clin Sci (Lond) 2023; 137:1721-1751. [PMID: 37986616 PMCID: PMC10665130 DOI: 10.1042/cs20230319] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 11/01/2023] [Accepted: 11/14/2023] [Indexed: 11/22/2023]
Abstract
Ageing is a complex biological process associated with increased morbidity and mortality. Nine classic, interdependent hallmarks of ageing have been proposed involving genetic and biochemical pathways that collectively influence ageing trajectories and susceptibility to pathology in humans. Ageing skeletal muscle undergoes profound morphological and physiological changes associated with loss of strength, mass, and function, a condition known as sarcopenia. The aetiology of sarcopenia is complex and whilst research in this area is growing rapidly, there is a relative paucity of human studies, particularly in older women. Here, we evaluate how the nine classic hallmarks of ageing: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication contribute to skeletal muscle ageing and the pathophysiology of sarcopenia. We also highlight five novel hallmarks of particular significance to skeletal muscle ageing: inflammation, neural dysfunction, extracellular matrix dysfunction, reduced vascular perfusion, and ionic dyshomeostasis, and discuss how the classic and novel hallmarks are interconnected. Their clinical relevance and translational potential are also considered.
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Affiliation(s)
- Antoneta Granic
- AGE Research Group, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, U.K
- NIHR Newcastle Biomedical Research Centre, Newcastle University and Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, U.K
| | - Karen Suetterlin
- AGE Research Group, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, U.K
- NIHR Newcastle Biomedical Research Centre, Newcastle University and Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, U.K
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Centre for Life, Newcastle upon Tyne, U.K
| | - Tea Shavlakadze
- Regeneron Pharmaceuticals Inc., Tarrytown, New York, NY, U.S.A
| | - Miranda D. Grounds
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, the University of Western Australia, Perth, WA 6009, Australia
| | - Avan A. Sayer
- AGE Research Group, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, U.K
- NIHR Newcastle Biomedical Research Centre, Newcastle University and Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, U.K
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9
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Kemfack AM, Hernández-Morato I, Moayedi Y, Pitman MJ. Transcriptome analysis of left versus right intrinsic laryngeal muscles associated with innervation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.25.554869. [PMID: 37873132 PMCID: PMC10592802 DOI: 10.1101/2023.08.25.554869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Objectives/Hypothesis Recurrent laryngeal nerve injury diagnosed as idiopathic or due to short-term surgery-related intubation exhibits a higher incidence of left-sided paralysis. While this is often attributed to nerve length, it is hypothesized there are asymmetric differences in the expression of genes related to neuromuscular function that may impact reinnervation and contribute to this laterality phenomenon. To test this hypothesis, this study analyzes the transcriptome profiles of the intrinsic laryngeal muscles (ILMs), comparing gene expression in the left versus right, with particular attention to genetic pathways associated with neuromuscular function. Study Design Laboratory experiment. Methods RNA was extracted from the left and right sides of the rat posterior cricoarytenoid (PCA), lateral thyroarytenoid (LTA), and medial thyroarytenoid (MTA), respectively. After high-throughput RNA-Sequencing (RNA-Seq), 88 samples were organized into 12 datasets according to their age (P15/adult), sex (male/female), and muscle type (PCA/LTA/MTA). A comprehensive bioinformatics analysis was conducted to compare the left-right ILMs across different conditions. Results 774 differentially expressed genes (DEGs) were identified across the 12 experimental groups, revealing age, sex, and muscle-specific differences between the left versus right ILMs. Enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways implicated several genes with a left-right laryngeal muscle asymmetry. These genes are associated with neuronal and muscular physiology, immune/inflammatory response, and hormone control. Conclusion Bioinformatics analysis confirmed divergent transcriptome profiles between the left-right ILMs. This preliminary study identifies putative gene targets that will characterize ILM laterality. Level of Evidence N/A. LAY SUMMARY Vocal fold paralysis is more common on the left. This study shows left versus right differences in gene expression related to innervation, suggesting the increased rate of left recurrent laryngeal nerve paralysis may be associated with genetic differences, not just nerve length.
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10
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Orssatto LBR, Blazevich AJ, Trajano GS. Ageing reduces persistent inward current contribution to motor neurone firing: Potential mechanisms and the role of exercise. J Physiol 2023; 601:3705-3716. [PMID: 37488952 DOI: 10.1113/jp284603] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 06/26/2023] [Indexed: 07/26/2023] Open
Abstract
Nervous system deterioration is a primary driver of age-related motor impairment. The motor neurones, which act as the interface between the central nervous system and the muscles, play a crucial role in amplifying excitatory synaptic input to produce the desired motor neuronal firing output. For this, they utilise their ability to generate persistent (long-lasting) depolarising currents that increase cell excitability, and both amplify and prolong the output activity of motor neurones for a given synaptic input. Modulation of these persistent inward currents (PICs) contributes to the motor neurones' capacities to attain the required firing frequencies and rapidly modulate them to competently complete most tasks. Thus, PICs are crucial for adequate movement generation. Impairments in intrinsic motor neurone properties can impact motor unit firing capacity, with convincing evidence indicating that the PIC contribution to motor neurone firing is reduced in older adults. Indeed, this could be an important mechanism underpinning the age-related reductions in strength and physical function. Furthermore, resistance training has emerged as a promising intervention to counteract age-associated PIC impairments, with changes in PICs being correlated with improvements in muscular strength and physical function after training. In this review, we present the current knowledge of the PIC magnitude decline during ageing and discuss whether reduced serotonergic and noradrenergic input onto the motor neurones, voltage-gated calcium channel dysfunction or inhibitory input impairments are candidates that: (i) explain age-related reductions in the PIC contribution to motor neurone firing and (ii) underpin the enhanced PIC contribution to motor neurone firing following resistance training in older adults.
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Affiliation(s)
- Lucas B R Orssatto
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Faculty of Health, Deakin University, Geelong, VIC, Australia
| | - Anthony J Blazevich
- School of Medical and Health Sciences, Centre for Human Performance, Edith Cowan University, Joondalup, WA, Australia
| | - Gabriel S Trajano
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, QLD, Australia
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11
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Sahota VK, Stone A, Woodling NS, Spiers JG, Steinert JR, Partridge L, Augustin H. Plum modulates Myoglianin and regulates synaptic function in D. melanogaster. Open Biol 2023; 13:230171. [PMID: 37699519 PMCID: PMC10497343 DOI: 10.1098/rsob.230171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 08/14/2023] [Indexed: 09/14/2023] Open
Abstract
Alterations in the neuromuscular system underlie several neuromuscular diseases and play critical roles in the development of sarcopenia, the age-related loss of muscle mass and function. Mammalian Myostatin (MST) and GDF11, members of the TGF-β superfamily of growth factors, are powerful regulators of muscle size in both model organisms and humans. Myoglianin (MYO), the Drosophila homologue of MST and GDF11, is a strong inhibitor of synaptic function and structure at the neuromuscular junction in flies. Here, we identified Plum, a transmembrane cell surface protein, as a modulator of MYO function in the larval neuromuscular system. Reduction of Plum in the larval body-wall muscles abolishes the previously demonstrated positive effect of attenuated MYO signalling on both muscle size and neuromuscular junction structure and function. In addition, downregulation of Plum on its own results in decreased synaptic strength and body weight, classifying Plum as a (novel) regulator of neuromuscular function and body (muscle) size. These findings offer new insights into possible regulatory mechanisms behind ageing- and disease-related neuromuscular dysfunctions in humans and identify potential targets for therapeutic interventions.
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Affiliation(s)
- Virender K. Sahota
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Aelfwin Stone
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Nathaniel S. Woodling
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Jereme G. Spiers
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Joern R. Steinert
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Linda Partridge
- Institute of Healthy Ageing, and GEE, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, Cologne 50931, Germany
| | - Hrvoje Augustin
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
- Institute of Healthy Ageing, and GEE, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, Cologne 50931, Germany
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12
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GrönholdtKlein M, Gorzi A, Wang L, Edström E, Rullman E, Altun M, Ulfhake B. Emergence and Progression of Behavioral Motor Deficits and Skeletal Muscle Atrophy across the Adult Lifespan of the Rat. BIOLOGY 2023; 12:1177. [PMID: 37759577 PMCID: PMC10526071 DOI: 10.3390/biology12091177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 08/14/2023] [Accepted: 08/21/2023] [Indexed: 09/29/2023]
Abstract
The facultative loss of muscle mass and function during aging (sarcopenia) poses a serious threat to our independence and health. When activities of daily living are impaired (clinical phase), it appears that the processes leading to sarcopenia have been ongoing in humans for decades (preclinical phase). Here, we examined the natural history of sarcopenia in male outbred rats to compare the occurrence of motor behavioral deficits with the degree of muscle wasting and to explore the muscle-associated processes of the preclinical and clinical phases, respectively. Selected metrics were validated in female rats. We used the soleus muscle because of its long duty cycles and its importance in postural control. Results show that gait and coordination remain intact through middle age (40-60% of median lifespan) when muscle mass is largely preserved relative to body weight. However, the muscle shows numerous signs of remodeling with a shift in myofiber-type composition toward type I. As fiber-type prevalence shifted, fiber-type clustering also increased. The number of hybrid fibers, myofibers with central nuclei, and fibers expressing embryonic myosin increased from being barely detectable to a significant number (5-10%) at late middle age. In parallel, TGFβ1, Smad3, FBXO32, and MuRF1 mRNAs increased. In early (25-month-old) and advanced (30-month-old) aging, gait and coordination deteriorate with the progressive loss of muscle mass. In late middle age and early aging due to type II atrophy (>50%) followed by type I atrophy (>50%), the number of myofibers did not correlate with this process. In advanced age, atrophy is accompanied by a decrease in SCs and βCatenin mRNA, whereas several previously upregulated transcripts were downregulated. The re-expression of embryonic myosin in myofibers and the upregulation of mRNAs encoding the γ-subunit of the nicotinic acetylcholine receptor, the neuronal cell adhesion molecule, and myogenin that begins in late middle age suggest that one mechanism driving sarcopenia is the disruption of neuromuscular connectivity. We conclude that sarcopenia in rats, as in humans, has a long preclinical phase in which muscle undergoes extensive remodeling to maintain muscle mass and function. At later time points, these adaptive mechanisms fail, and sarcopenia becomes clinically manifest.
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Affiliation(s)
- Max GrönholdtKlein
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden;
| | - Ali Gorzi
- Department of Sport Sciences, University of Zanjan, Zanjan 45371-38791, Iran;
| | - Lingzhan Wang
- Department of Human Anatomy, Histology and Embryology, Inner Mongolia Minzu University, Tongliao 028000, China;
| | - Erik Edström
- Department of Clinical Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden;
| | - Eric Rullman
- Department of Laboratory Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden; (E.R.); (M.A.)
| | - Mikael Altun
- Department of Laboratory Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden; (E.R.); (M.A.)
| | - Brun Ulfhake
- Department of Laboratory Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden; (E.R.); (M.A.)
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13
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So HK, Kim H, Lee J, You CL, Yun CE, Jeong HJ, Jin EJ, Jo Y, Ryu D, Bae GU, Kang JS. Protein Arginine Methyltransferase 1 Ablation in Motor Neurons Causes Mitochondrial Dysfunction Leading to Age-related Motor Neuron Degeneration with Muscle Loss. RESEARCH (WASHINGTON, D.C.) 2023; 6:0158. [PMID: 37342629 PMCID: PMC10278992 DOI: 10.34133/research.0158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 05/08/2023] [Indexed: 06/23/2023]
Abstract
Neuromuscular dysfunction is tightly associated with muscle wasting that occurs with age or due to degenerative diseases. However, the molecular mechanisms underlying neuromuscular dysfunction are currently unclear. Recent studies have proposed important roles of Protein arginine methyltransferase 1 (Prmt1) in muscle stem cell function and muscle maintenance. In the current study, we set out to determine the role of Prmt1 in neuromuscular function by generating mice with motor neuron-specific ablation of Prmt1 (mnKO) using Hb9-Cre. mnKO exhibited age-related motor neuron degeneration and neuromuscular dysfunction leading to premature muscle loss and lethality. Prmt1 deficiency also impaired motor function recovery and muscle reinnervation after sciatic nerve injury. The transcriptome analysis of aged mnKO lumbar spinal cords revealed alterations in genes related to inflammation, cell death, oxidative stress, and mitochondria. Consistently, mnKO lumbar spinal cords of sciatic nerve injury model or aged mice exhibited elevated cellular stress response in motor neurons. Furthermore, Prmt1 inhibition in motor neurons elicited mitochondrial dysfunction. Our findings demonstrate that Prmt1 ablation in motor neurons causes age-related motor neuron degeneration attributing to muscle loss. Thus, Prmt1 is a potential target for the prevention or intervention of sarcopenia and neuromuscular dysfunction related to aging.
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Affiliation(s)
- Hyun-Kyung So
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
- Single Cell Network Research Center, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Hyebeen Kim
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
- Single Cell Network Research Center, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Jinwoo Lee
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
- Research Institute of Aging-Related Diseases, AniMusCure, Inc., Suwon, Korea
| | - Chang-Lim You
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
- Single Cell Network Research Center, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Chae-Eun Yun
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
- Single Cell Network Research Center, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Hyeon-Ju Jeong
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
- Single Cell Network Research Center, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Eun-Ju Jin
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Yunju Jo
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Dongryeol Ryu
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Gyu-Un Bae
- Drug Information Research Institute, Muscle Physiome Research Center, College of Pharmacy, Sookmyung Women’s University, Seoul, Korea
| | - Jong-Sun Kang
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
- Single Cell Network Research Center, Sungkyunkwan University School of Medicine, Suwon, Korea
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14
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Rich KA, Pino MG, Yalvac ME, Fox A, Harris H, Balch MHH, Arnold WD, Kolb SJ. Impaired motor unit recovery and maintenance in a knock-in mouse model of ALS-associated Kif5a variant. Neurobiol Dis 2023; 182:106148. [PMID: 37164288 PMCID: PMC10874102 DOI: 10.1016/j.nbd.2023.106148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 05/03/2023] [Accepted: 05/07/2023] [Indexed: 05/12/2023] Open
Abstract
Kinesin family member 5A (KIF5A) is an essential, neuron-specific microtubule-associated motor protein responsible for the anterograde axonal transport of various cellular cargos. Loss of function variants in the N-terminal, microtubule-binding domain are associated with hereditary spastic paraplegia and hereditary motor neuropathy. These variants result in a loss of the ability of the mutant protein to process along microtubules. Contrastingly, gain of function splice-site variants in the C-terminal, cargo-binding domain of KIF5A are associated with amyotrophic lateral sclerosis (ALS), a neurodegenerative disease involving death of upper and lower motor neurons, ultimately leading to degradation of the motor unit (MU; an alpha motor neuron and all the myofibers it innervates) and death. These ALS-associated variants result in loss of autoinhibition, increased procession of the mutant protein along microtubules, and altered cargo binding. To study the molecular and cellular consequences of ALS-associated variants in vivo, we introduced the murine homolog of an ALS-associated KIF5A variant into C57BL/6 mice using CRISPR-Cas9 gene editing which produced mutant Kif5a mRNA and protein in neuronal tissues of heterozygous (Kif5a+/c.3005+1G>A; HET) and homozygous (Kif5ac.3005+1G>A/c.3005+1G>A; HOM) mice. HET and HOM mice appeared normal in behavioral and electrophysiological (compound muscle action potential [CMAP] and MU number estimation [MUNE]) outcome measures at one year of age. When subjected to sciatic nerve injury, HET and HOM mice have delayed and incomplete recovery of the MUNE compared to wildtype (WT) mice suggesting an impairment in MU repair. Moreover, aged mutant Kif5a mice (aged two years) had reduced MUNE independent of injury, and exacerbation of the delayed and incomplete recovery after injury compared to aged WT mice. These data suggest that ALS-associated variants may result in an impairment of the MU to respond to biological challenges such as injury and aging, leading to a failure of MU repair and maintenance. In this report, we present the behavioral, electrophysiological and pathological characterization of mice harboring an ALS-associated Kif5a variant to understand the functional consequences of KIF5A C-terminal variants in vivo.
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Affiliation(s)
- Kelly A Rich
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Megan G Pino
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Mehmet E Yalvac
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Ashley Fox
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Hallie Harris
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Maria H H Balch
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - W David Arnold
- NextGen Precision Health, University of Missouri, MO, USA; Department of Physical Medicine and Rehabilitation, University of Missouri, MO, USA
| | - Stephen J Kolb
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Biological Chemistry & Pharmacology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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15
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Age-sensitive high density surface electromyogram indices for detecting muscle fatigue using core shape modelling. Biomed Signal Process Control 2023. [DOI: 10.1016/j.bspc.2022.104446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Monti E, Sarto F, Sartori R, Zanchettin G, Löfler S, Kern H, Narici MV, Zampieri S. C-terminal agrin fragment as a biomarker of muscle wasting and weakness: a narrative review. J Cachexia Sarcopenia Muscle 2023; 14:730-744. [PMID: 36772862 PMCID: PMC10067498 DOI: 10.1002/jcsm.13189] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/30/2022] [Accepted: 01/16/2023] [Indexed: 02/12/2023] Open
Abstract
Ageing is accompanied by an inexorable loss of muscle mass and functionality and represents a major risk factor for numerous diseases such as cancer, diabetes and cardiovascular and pulmonary diseases. This progressive loss of muscle mass and function may also result in the insurgence of a clinical syndrome termed sarcopenia, exacerbated by inactivity and disease. Sarcopenia and muscle weakness yield the risk of falls and injuries, heavily impacting on health and social costs. Thus, screening, monitoring and prevention of conditions inducing muscle wasting and weakness are essential to improve life quality in the ageing modern society. To this aim, the reliability of easily accessible and non-invasive blood-derived biomarkers is being evaluated. C-terminal agrin fragment (CAF) has been widely investigated as a neuromuscular junction (NMJ)-related biomarker of muscle dysfunction. This narrative review summarizes and critically discusses, for the first time, the studies measuring CAF concentration in young and older, healthy and diseased individuals, cross-sectionally and in response to inactivity and physical exercise, providing possible explanations behind the discrepancies observed in the literature. To identify the studies investigating CAF in the above-mentioned conditions, all the publications found in PubMed, written in English and measuring this biomarker in blood from 2013 (when CAF was firstly measured in human serum) to 2022 were included in this review. CAF increases with age and in sarcopenic individuals when compared with age-matched, non-sarcopenic peers. In addition, CAF was found to be higher than controls in other muscle wasting conditions, such as diabetes, COPD, chronic heart failure and stroke, and in pancreatic and colorectal cancer cachectic patients. As agrin is also expressed in kidney glomeruli, chronic kidney disease and transplantation were shown to have a profound impact on CAF independently from muscle wasting. CAF concentration raises following inactivity and seems to be lowered or maintained by exercise training. Finally, CAF was reported to be cross-sectionally correlated to appendicular lean mass, handgrip and gait speed; whether longitudinal changes in CAF are associated with those in muscle mass or performance following physical exercise is still controversial. CAF seems a reliable marker to assess muscle wasting in ageing and disease, also correlating with measurements of appendicular lean mass and muscle function. Future research should aim at enlarging sample size and accurately reporting the medical history of each patient, to normalize for any condition, including chronic kidney disease, that may influence the circulating concentration of this biomarker.
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Affiliation(s)
- Elena Monti
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Stanford School of Medicine, Stanford, CA, USA
| | - Fabio Sarto
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Roberta Sartori
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,Veneto Institute of Molecular Medicine, Padova, Italy
| | - Gianpietro Zanchettin
- Department of Surgery, Oncology, and Gastroenterology, University of Padova, Padova, Italy
| | - Stefan Löfler
- Ludwig Boltzmann Institute for Rehabilitation Research, Wien, Austria.,Centre of Active Ageing, Sankt Poelten, Austria
| | - Helmut Kern
- Ludwig Boltzmann Institute for Rehabilitation Research, Wien, Austria.,Centre of Active Ageing, Sankt Poelten, Austria
| | - Marco Vincenzo Narici
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,CIR-MYO Myology Center, University of Padova, Padova, Italy
| | - Sandra Zampieri
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,Department of Surgery, Oncology, and Gastroenterology, University of Padova, Padova, Italy.,Ludwig Boltzmann Institute for Rehabilitation Research, Wien, Austria.,Centre of Active Ageing, Sankt Poelten, Austria.,CIR-MYO Myology Center, University of Padova, Padova, Italy
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17
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Puladi B, Ooms M, Geijtenbeek T, Trinler U, Houschyar KS, Gruber LJ, Motmaen I, Rashad A, Hölzle F, Modabber A. Tolerable degree of muscle sacrifice when harvesting a vastus lateralis or myocutaneous anterolateral thigh flap. J Plast Reconstr Aesthet Surg 2023; 77:94-103. [PMID: 36563640 DOI: 10.1016/j.bjps.2022.10.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 08/08/2022] [Accepted: 10/11/2022] [Indexed: 12/24/2022]
Abstract
The myocutaneous anterolateral thigh (ALT) and vastus lateralis (VL) flaps include a large muscle mass and a sufficient vascular pedicle, and they have been used for decades to reconstruct traumatic and acquired defects of the head and neck and extremities. In spite of these benefits, musculoskeletal dysfunction was reported in nearly 1 out of 20 patients at follow-up. It is unclear whether the recently proposed muscle-sparing flap-raising approach could preserve VL muscle function and whether patients at increased risk could benefit from such an approach. Therefore, we performed a predictive dynamic gait simulation based on a biological motion model with gradual weakening of the VL during a self-selected and fast walking speed to determine the compensable degree of VL muscle reduction. Muscle force, joint angle, and joint moment were measured. Our study showed that VL muscle reduction could be compensated up to a certain degree, which could explain the observed incidence of musculoskeletal dysfunction. In elderly or fragile patients, the VL muscle should not be reduced by 50% or more, which could be achieved by muscle-sparing flap-raising of the superficial partition only. In young or athletic patients, a VL muscle reduction of 10%, which corresponds to a muscle cuff, has no relevant effect. Yet, a reduction of more than 30% leads to relevant weakening of the quadriceps. Therefore, in this patient population with the need for a large portion of muscle, alternative flaps should be considered. This study can serve as the first basis for further investigations of human locomotion after flap-raising.
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Affiliation(s)
- Behrus Puladi
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, 52074 Aachen, Germany; Institute of Medical Informatics, University Hospital RWTH Aachen, 52074 Aachen, Germany.
| | - Mark Ooms
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, 52074 Aachen, Germany.
| | - Thomas Geijtenbeek
- BioMechanical Engineering, Delft University of Technology, 2628 Delft, the Netherlands
| | - Ursula Trinler
- Andreas Wentzensen Research Institute, BG Clinic Ludwigshafen, 67071 Ludwigshafen, Germany
| | - Khosrow Siamak Houschyar
- Department of Plastic and Hand Surgery, Burn Unit, Trauma Center Bergmannstrost Halle, 06112 Halle, Germany
| | - Lennart Johannes Gruber
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, 52074 Aachen, Germany
| | - Ila Motmaen
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, 52074 Aachen, Germany
| | - Ashkan Rashad
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, 52074 Aachen, Germany
| | - Frank Hölzle
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, 52074 Aachen, Germany
| | - Ali Modabber
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, 52074 Aachen, Germany
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18
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Swart SB, den Otter AR, Lamoth CJC. Natural ageing primarily affects the initial response to a sustained walking perturbation but not the ability to adapt over time. Front Physiol 2023; 14:1065974. [PMID: 36909231 PMCID: PMC9995672 DOI: 10.3389/fphys.2023.1065974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 02/13/2023] [Indexed: 02/25/2023] Open
Abstract
The ability to flexibly respond and adapt the walking pattern over time to unexpected gait perturbations is pivotal for safe and efficient locomotion. However, these abilities might be affected by age due to age-related changes in sensorimotor functioning. In this cross-sectional lifespan study, we used a split-belt paradigm to determine how age affects the initial response (i.e., flexibility)-and the ability to adapt after prolonged exposure-to a sustained gait perturbation. Healthy adults (N = 75) of different ages (12-13 per decade) were included and walked on a split-belt treadmill, in which a sustained gait perturbation was imposed by increasing one of the belt speeds. Linear regression models, with the evoked spatiotemporal gait asymmetry during the early perturbation and late adaptation, were performed to determine the effects of age on the flexibility and adaptability to split-belt walking. Results showed that the flexibility to respond to an unexpected perturbation decreased across the lifespan, as evidenced by a greater step length asymmetry (SLA) during the early perturbation phase. Despite this reduced flexibility in step lengths, late adaptation levels in SLA were comparable across different ages. With increasing age, however, subjects needed more steps to reach a stable level in SLA. Finally, when the belts were set to symmetrical speeds again, the magnitude of SLA (i.e., the aftereffects) increased with age. Collectively, these findings suggest that natural ageing comes with a decrease in gait flexibility, while the ability to adapt to split-belt walking was not affected by age-only how adaptation was achieved.
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Affiliation(s)
- S B Swart
- Department of Human Movement Sciences, University of Groningen, University Medical Centre Groningen, Groningen, Netherlands
| | - A R den Otter
- Department of Human Movement Sciences, University of Groningen, University Medical Centre Groningen, Groningen, Netherlands
| | - C J C Lamoth
- Department of Human Movement Sciences, University of Groningen, University Medical Centre Groningen, Groningen, Netherlands
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19
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Takino K, Kameshima M, Asai C, Kawamura I, Tomita S, Sato H, Hirakawa A, Yamada S. Neuromuscular electrical stimulation after cardiovascular surgery mitigates muscle weakness in older individuals with diabetes. Ann Phys Rehabil Med 2022; 66:101659. [PMID: 35272065 DOI: 10.1016/j.rehab.2022.101659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/18/2022] [Accepted: 01/25/2022] [Indexed: 12/03/2022]
Abstract
BACKGROUND Cardiovascular surgery leads to postsurgical muscle weakness, probably because of muscle proteolysis and peripheral nerve dysfunction, which are augmented by aging and diabetes mellitus. OBJECTIVE We examined the effect of neuromuscular electrical stimulation (NMES) on postsurgical muscle weakness in older individuals with diabetes mellitus. METHODS We conducted a multicentre, randomized, controlled trial, and screened consecutive patients with diabetes who underwent cardiovascular surgery for eligibility (age ≥ 65 years). Those included were randomly assigned to the NMES or the sham group. The primary outcome was the percent change in isometric knee extension strength (%ΔIKES) from preoperative to postoperative day 7. Secondary outcomes were the percent change in usual (%ΔUWS), maximum walking speed (%ΔMWS), and grip strength (%ΔGS). A statistician who was blinded to group allocation used intention-to-treat analysis (student t test). RESULTS Of 1151 participants screened for eligibility, 180 (NMES, n = 90; sham, n = 90) were included in the primary analysis. %ΔIKES was significantly lower in the NMES than sham group (NMES: mean -2%, 95% confidence interval [CI] -6 to 1; sham: -13%, 95% CI -17 to -9, p < 0.001). Among the secondary outcomes, %ΔMWS was significantly lower and %ΔUWS and %ΔGS were lower, although not significantly, in the NMES than sham group. CONCLUSIONS A short course of NMES (< 1 week) mitigated postsurgical muscle weakness and functional decline in older persons with diabetes mellitus. NMES could be recommended as a part of postsurgical rehabilitation in older people with diabetes mellitus, especially those with a low functional reserve.
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Affiliation(s)
- Koya Takino
- Department of Cardiac Rehabilitation, Gifu Heart Center, 4-14-4, Yabuta-minami, Gifu, Japan; Program in Physical and Occupational Therapy, Nagoya University Graduate School of Medicine, Japan
| | - Masataka Kameshima
- Department of Cardiac Rehabilitation, Nagoya Heart Center, 1-1-11, Sunadabashi, higasi-ku, Nagoya, Japan
| | - Chikako Asai
- Department of Cardiac Rehabilitation, Toyohashi Heart Center, 1-21, Gobudori, Oyamacho, Toyohasi, Japan
| | - Itta Kawamura
- Department of Cardiology, Gifu Heart Center, 4-14-4, Yabuta-minami, Gifu, Japan
| | - Shinji Tomita
- Department of Cardiovascular Surgery, Gifu Heart Center, 4-14-4, Yabuta-minami, Gifu, Japan
| | - Hiroyuki Sato
- Division of Biostatistics and Data Science, Clinical Research Center, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan
| | - Akihiro Hirakawa
- Division of Biostatistics and Data Science, Clinical Research Center, Tokyo Medical and Dental University Hospital of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan
| | - Sumio Yamada
- Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya, Japan.
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20
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Bouredji Z, Argaw A, Frenette J. The inflammatory response, a mixed blessing for muscle homeostasis and plasticity. Front Physiol 2022; 13:1032450. [PMID: 36505042 PMCID: PMC9726740 DOI: 10.3389/fphys.2022.1032450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 11/10/2022] [Indexed: 11/24/2022] Open
Abstract
Skeletal muscle makes up almost half the body weight of heathy individuals and is involved in several vital functions, including breathing, thermogenesis, metabolism, and locomotion. Skeletal muscle exhibits enormous plasticity with its capacity to adapt to stimuli such as changes in mechanical loading, nutritional interventions, or environmental factors (oxidative stress, inflammation, and endocrine changes). Satellite cells and timely recruited inflammatory cells are key actors in muscle homeostasis, injury, and repair processes. Conversely, uncontrolled recruitment of inflammatory cells or chronic inflammatory processes leads to muscle atrophy, fibrosis and, ultimately, impairment of muscle function. Muscle atrophy and loss of function are reported to occur either in physiological situations such as aging, cast immobilization, and prolonged bed rest, as well as in many pathological situations, including cancers, muscular dystrophies, and several other chronic illnesses. In this review, we highlight recent discoveries with respect to the molecular mechanisms leading to muscle atrophy caused by modified mechanical loading, aging, and diseases. We also summarize current perspectives suggesting that the inflammatory process in muscle homeostasis and repair is a double-edged sword. Lastly, we review recent therapeutic approaches for treating muscle wasting disorders, with a focus on the RANK/RANKL/OPG pathway and its involvement in muscle inflammation, protection and regeneration processes.
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Affiliation(s)
- Zineb Bouredji
- Centre Hospitalier Universitaire de Québec, Centre de Recherche du Centre Hospitalier de l’Université Laval (CRCHUQ-CHUL), Axe Neurosciences, Université Laval, Quebec City, QC, Canada
| | - Anteneh Argaw
- Centre Hospitalier Universitaire de Québec, Centre de Recherche du Centre Hospitalier de l’Université Laval (CRCHUQ-CHUL), Axe Neurosciences, Université Laval, Quebec City, QC, Canada
| | - Jérôme Frenette
- Centre Hospitalier Universitaire de Québec, Centre de Recherche du Centre Hospitalier de l’Université Laval (CRCHUQ-CHUL), Axe Neurosciences, Université Laval, Quebec City, QC, Canada,Département de Réadaptation, Faculté de Médecine, Université Laval, Quebec City, QC, Canada,*Correspondence: Jérôme Frenette,
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21
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Mear E, Gladwell VF, Pethick J. The Effect of Breaking Up Sedentary Time with Calisthenics on Neuromuscular Function: A Preliminary Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:14597. [PMID: 36361476 PMCID: PMC9653850 DOI: 10.3390/ijerph192114597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/02/2022] [Accepted: 11/04/2022] [Indexed: 06/16/2023]
Abstract
The ageing process results in reduced neuromuscular function. This alongside prolonged sedentary behaviour is associated with decreased muscle strength, force control and ability to maintain balance. Breaking up sedentary time with regular bouts of physical activity has numerous health benefits, though the effects on neuromuscular function are unknown. This study investigated the effect of breaking up sedentary time with calisthenic exercise on neuromuscular function. 17 healthy adults (33 ± 13.1 years), who spent ≥6 h/day sitting, were assigned to a four-week calisthenics intervention (n = 8) or control group (n = 9). The calisthenics intervention involved performing up to eight sets of exercises during the working day (09:00-17:00); with one set consisting of eight repetitions of five difference exercises (including squats and lunges). Before and immediately after the intervention, measures of knee extensor maximal voluntary contraction (MVC) and submaximal force control (measures of the magnitude and complexity of force fluctuations), and dynamic balance (Y balance test) were taken. The calisthenics intervention resulted in a significant increase in knee extensor MVC (p = 0.036), significant decreases in the standard deviation (p = 0.031) and coefficient of variation (p = 0.016) of knee extensor force fluctuations during contractions at 40% MVC, and a significant increase in Y balance test posterolateral reach with left leg stance (p = 0.046). These results suggest that breaking up sedentary time with calisthenics may be effective at increasing muscle strength, force steadiness and dynamic balance all of which might help reduce the effects of the ageing process.
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Affiliation(s)
- Emily Mear
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Colchester CO4 3SQ, UK
| | | | - Jamie Pethick
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Colchester CO4 3SQ, UK
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22
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Inns TB, Bass JJ, Hardy EJ, Wilkinson DJ, Stashuk DW, Atherton PJ, Phillips BE, Piasecki M. Motor unit dysregulation following 15 days of unilateral lower limb immobilisation. J Physiol 2022; 600:4753-4769. [PMID: 36088611 PMCID: PMC9827843 DOI: 10.1113/jp283425] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 08/19/2022] [Indexed: 01/12/2023] Open
Abstract
Disuse atrophy, caused by situations of unloading such as limb immobilisation, causes a rapid yet diverging reduction in skeletal muscle function when compared to muscle mass. While mechanistic insight into the loss of mass is well studied, deterioration of muscle function with a focus towards the neural input to muscle remains underexplored. This study aimed to determine the role of motor unit adaptation in disuse-induced neuromuscular deficits. Ten young, healthy male volunteers underwent 15 days of unilateral lower limb immobilisation with intramuscular electromyography (iEMG) bilaterally recorded from the vastus lateralis (VL) during knee extensor contractions normalised to maximal voluntary contraction (MVC), pre and post disuse. Muscle cross-sectional area was determined by ultrasound. Individual MUs were sampled and analysed for changes in motor unit (MU) discharge and MU potential (MUP) characteristics. VL CSA was reduced by approximately 15% which was exceeded by a two-fold decrease of 31% in muscle strength in the immobilised limb, with no change in either parameter in the non-immobilised limb. Parameters of MUP size were reduced by 11% to 24% with immobilisation, while neuromuscular junction (NMJ) transmission instability remained unchanged, and MU firing rate decreased by 8% to 11% at several contraction levels. All adaptations were observed in the immobilised limb only. These findings highlight impaired neural input following immobilisation reflected by suppressed MU firing rate which may underpin the disproportionate reductions of strength relative to muscle size. KEY POINTS: Muscle mass and function decline rapidly in situations of disuse such as bed rest and limb immobilisation. The reduction in muscle function commonly exceeds that of muscle mass, which may be associated with the dysregulation of neural input to muscle. We have used intramuscular electromyography to sample individual motor unit and near fibre potentials from the vastus lateralis following 15 days of unilateral limb immobilisation. Following disuse, the disproportionate loss of muscle strength when compared to size coincided with suppressed motor unit firing rate. These motor unit adaptations were observed at multiple contraction levels and in the immobilised limb only. Our findings demonstrate neural dysregulation as a key component of functional loss following muscle disuse in humans.
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Affiliation(s)
- Thomas B. Inns
- Centre Of Metabolism, Ageing & PhysiologyMRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRCUniversity of NottinghamDerbyUK
| | - Joseph J. Bass
- Centre Of Metabolism, Ageing & PhysiologyMRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRCUniversity of NottinghamDerbyUK
| | - Edward J.O. Hardy
- Centre Of Metabolism, Ageing & PhysiologyMRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRCUniversity of NottinghamDerbyUK
- Department of Surgery and AnaestheticsRoyal Derby HospitalDerbyUK
| | - Daniel J. Wilkinson
- Centre Of Metabolism, Ageing & PhysiologyMRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRCUniversity of NottinghamDerbyUK
| | - Daniel W. Stashuk
- Department of Systems Design EngineeringUniversity of WaterlooOntarioCanada
| | - Philip J. Atherton
- Centre Of Metabolism, Ageing & PhysiologyMRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRCUniversity of NottinghamDerbyUK
| | - Bethan E. Phillips
- Centre Of Metabolism, Ageing & PhysiologyMRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRCUniversity of NottinghamDerbyUK
| | - Mathew Piasecki
- Centre Of Metabolism, Ageing & PhysiologyMRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRCUniversity of NottinghamDerbyUK
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Lee H, Park YM, Kang N. Unilateral hand force control impairments in older women. EXCLI JOURNAL 2022; 21:1231-1244. [PMID: 36381646 PMCID: PMC9650698 DOI: 10.17179/excli2022-5362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 09/20/2022] [Indexed: 11/25/2022]
Abstract
Older women may experience deficits in sensorimotor control at their upper limb because of aging progress compromising the motor system. This study aimed to investigate whether younger and older women differ in sensorimotor capabilities assessed by unilateral force control performances at a lower targeted force level. Twenty-one older and 21 younger women performed isometric unilateral force control tasks at 10 % of maximum voluntary contraction for each hand, respectively. Purdue Pegboard Test (PPT) was used to measure unilateral hand dexterity. Five force control variables (i.e., maximal and submaximal force, force error, variability, and regularity) and PPT scores were analyzed in two-way mixed ANOVAs (Group × Hand Condition), respectively. The absolute force power was analyzed in three-way mixed ANOVA (Group × Hand Condition × Frequency Band). The findings revealed that older women produced less maximal and submaximal unilateral forces than in younger women. Greater variability, regularity, and force frequency oscillations below 4 Hz were observed in older women as compared with those in younger women. Force error in the dominant hand was greater in older women than those in younger women. Finally, older women showed lower PPT scores than younger women. These findings suggested that older women may have deficits in unilateral force control capabilities as well as motor dexterity.
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Affiliation(s)
- Hanall Lee
- Department of Human Movement Science, Incheon National University, Incheon, South Korea,Neuromechanical Rehabilitation Research Laboratory, Division of Sport Science, Incheon National University, Incheon, South Korea
| | - Young-Min Park
- Division of Health and Kinesiology, Incheon National University, Incheon, South Korea,Sport Science Institute & Health Promotion Center, Incheon National University, Incheon, South Korea
| | - Nyeonju Kang
- Department of Human Movement Science, Incheon National University, Incheon, South Korea,Neuromechanical Rehabilitation Research Laboratory, Division of Sport Science, Incheon National University, Incheon, South Korea,Sport Science Institute & Health Promotion Center, Incheon National University, Incheon, South Korea,Division of Sport Science & Sport Science Institute, Incheon National University, Incheon, South Korea,*To whom correspondence should be addressed: Nyeonju Kang, Neuromechanical Rehabilitation Research Laboratory, Division of Sport Science, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon, South Korea; Phone: +82 32 835 8573, Fax: +82 32 835 0788, E-mail:
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24
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Nichenko AS, Specht KS, Craige SM, Drake JC. Sensing local energetics to acutely regulate mitophagy in skeletal muscle. Front Cell Dev Biol 2022; 10:987317. [PMID: 36105350 PMCID: PMC9465048 DOI: 10.3389/fcell.2022.987317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 08/01/2022] [Indexed: 01/04/2023] Open
Abstract
The energetic requirements of skeletal muscle to sustain movement, as during exercise, is met largely by mitochondria, which form an intricate, interconnected reticulum. Maintenance of a healthy mitochondrial reticulum is essential for skeletal muscle function, suggesting quality control pathways are spatially governed. Mitophagy, the process by which damaged and/or dysfunctional regions of the mitochondrial reticulum are removed and degraded, has emerged as an integral part of the molecular response to exercise. Upregulation of mitophagy in response to acute exercise is directly connected to energetic sensing mechanisms through AMPK. In this review, we discuss the connection of mitophagy to muscle energetics and how AMPK may spatially control mitophagy through multiple potential means.
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25
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Verschueren A, Palminha C, Delmont E, Attarian S. Changes in neuromuscular function in elders: Novel techniques for assessment of motor unit loss and motor unit remodeling with aging. Rev Neurol (Paris) 2022; 178:780-787. [PMID: 35863917 DOI: 10.1016/j.neurol.2022.03.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/08/2022] [Accepted: 03/08/2022] [Indexed: 11/24/2022]
Abstract
Functional muscle fiber denervation is a major contributor to the decline in physical function observed with aging and is now a recognized cause of sarcopenia, a muscle disorder characterized by progressive and generalized degenerative loss of skeletal muscle mass, quality, and strength. There is an interrelationship between muscle strength, motor unit (MU) number, and aging, which suggests that a portion of muscle weakness in seniors may be attributable to the loss of functional MUs. During normal aging, there is a time-related progression of MU loss, an adaptive sprouting followed by a maladaptive sprouting, and continuing recession of terminal Schwann cells leading to a reduced capacity for compensatory reinnervation in elders. In amyotrophic lateral sclerosis, increasing age at onset predicts worse survival ALS and it is possible that age-related depletion of the motor neuron pool may worsen motor neuron disease. MUNE methods are used to estimate the number of functional MU, data from MUNIX arguing for motor neuron loss with aging will be reviewed. Recently, a new MRI technique MU-MRI could be used to assess the MU recruitment or explore the activity of a single MU. This review presents published studies on the changes of neuromuscular function with aging, then focusing on these two novel techniques for assessment of MU loss and MU remodeling.
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Affiliation(s)
- A Verschueren
- Reference Centre for Neuromuscular Disorders and ALS, CHU La Timone, Aix-Marseille University, 264, rue Saint Pierre, 13005 Marseille, France.
| | - C Palminha
- Reference Centre for Neuromuscular Disorders and ALS, CHU La Timone, Aix-Marseille University, 264, rue Saint Pierre, 13005 Marseille, France
| | - E Delmont
- Reference Centre for Neuromuscular Disorders and ALS, CHU La Timone, Aix-Marseille University, 264, rue Saint Pierre, 13005 Marseille, France
| | - S Attarian
- Reference Centre for Neuromuscular Disorders and ALS, CHU La Timone, Aix-Marseille University, 264, rue Saint Pierre, 13005 Marseille, France
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26
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Pethick J, Taylor MJD, Harridge SDR. Ageing and skeletal muscle force control: current perspectives and future directions. Scand J Med Sci Sports 2022; 32:1430-1443. [PMID: 35815914 PMCID: PMC9541459 DOI: 10.1111/sms.14207] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 05/23/2022] [Accepted: 06/22/2022] [Indexed: 11/29/2022]
Abstract
During voluntary muscle contractions, force output is characterized by constant inherent fluctuations, which can be quantified either according to their magnitude or temporal structure, that is, complexity. The presence of such fluctuations when targeting a set force indicates that control of force is not perfectly accurate, which can have significant implications for task performance. Compared to young adults, older adults demonstrate a greater magnitude and lower complexity in force fluctuations, indicative of decreased steadiness, and adaptability of force output, respectively. The nature of this loss‐of‐force control depends not only on the age of the individual but also on the muscle group performing the task, the intensity and type of contraction and whether the task is performed with additional cognitive load. Importantly, this age‐associated loss‐of‐force control is correlated with decreased performance in a range of activities of daily living and is speculated to be of greater importance for functional capacity than age‐associated decreases in maximal strength. Fortunately, there is evidence that acute physical activity interventions can reverse the loss‐of‐force control in older individuals, though whether this translates to improved functional performance and whether lifelong physical activity can protect against the changes have yet to be established. A number of mechanisms, related to both motor unit properties and the behavior of motor unit populations, have been proposed for the age‐associated changes in force fluctuations. It is likely, though, that age‐associated changes in force control are related to increased common fluctuations in the discharge times of motor units.
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Affiliation(s)
- Jamie Pethick
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Essex, UK
| | - Matthew J D Taylor
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Essex, UK
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27
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Marino FE, Sibson BE, Lieberman DE. The evolution of human fatigue resistance. J Comp Physiol B 2022; 192:411-422. [PMID: 35552490 PMCID: PMC9197885 DOI: 10.1007/s00360-022-01439-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 03/28/2022] [Accepted: 04/20/2022] [Indexed: 11/26/2022]
Abstract
Humans differ from African great apes in numerous respects, but the chief initial difference setting hominins on their unique evolutionary trajectory was habitual bipedalism. The two most widely supported selective forces for this adaptation are increased efficiency of locomotion and improved ability to feed in upright contexts. By 4 million years ago, hominins had evolved the ability to walk long distances but extreme selection for endurance capabilities likely occurred later in the genus Homo to help them forage, power scavenge and persistence hunt in hot, arid conditions. In this review we explore the hypothesis that to be effective long-distance walkers and especially runners, there would also have been a strong selective benefit among Homo to resist fatigue. Our hypothesis is that since fatigue is an important factor that limits the ability to perform endurance-based activities, fatigue resistance was likely an important target for selection during human evolution for improved endurance capabilities. We review the trade-offs between strength, power, and stamina in apes and Homo and discuss three biological systems that we hypothesize humans evolved adaptations for fatigue resistance: neurological, metabolic and thermoregulatory. We conclude that the evolution of endurance at the cost of strength and power likely also involved the evolution of mechanisms to resist fatigue.
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Affiliation(s)
- Frank E Marino
- School of Allied Health, Exercise and Sport Science, Charles Sturt University, Bathurst, NSW, 2795, Australia.
| | - Benjamin E Sibson
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Ave, Cambridge, MA, 02138, USA
| | - Daniel E Lieberman
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Ave, Cambridge, MA, 02138, USA
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28
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Jacob I, Johnson MI, Jones G, Jones A, Francis P. Age-related differences of vastus lateralis muscle morphology, contractile properties, upper body grip strength and lower extremity functional capability in healthy adults aged 18 to 70 years. BMC Geriatr 2022; 22:538. [PMID: 35768788 PMCID: PMC9241209 DOI: 10.1186/s12877-022-03183-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/01/2022] [Indexed: 11/19/2022] Open
Abstract
Background There is a lack of of cross-sectional research that has investigated muscle morphology, function, and functional capability in all age-bands of healthy adults. The primary aim of this study was to evaluate age-related differences in indices of vastus lateralis (VL) muscle morphology, function and functional capability in a sample of healthy males and females aged 18-70yrs. Secondary aims were to evaluate relationships between age and VL muscle morphology and function and functional capability. Methods B mode Ultrasonography and Tensiomyography were used to measure VL muscle thickness, pennation angle, fascicle length, and contractile properties in 274 healthy adults aged 18-70yrs. Measurements of grip strength and functional capability (1-min chair rise test) were also taken. Data analysis included descriptive statistics, correlations, one-way ANOVAs, and multiple regressions. Results Negative correlations were found between age and muscle thickness (rs = -.56), pennation angle (rs = -.50), fascicle length (rs = -.30), maximal displacement (rs = -.24), grip strength (rs = -.27) and the 1-min chair rise test (rs = -.32). Positive correlations were observed between age and the echo intensity of the muscle (rs = .40) and total contraction time (rs = .20). Differences in the indices of muscle health were noticeable between the 18–29 age band and the 50–59 and 60–70 age bands (p < 0.05). The interaction of age and level of physical activity predicted changes in the variables (r2 = .04—.32). Conclusion Age-related differences in muscle health are noticeable at 50 years of age, and age-related differences are larger in females compared to males. It was suggested that the thickness of the VL changed the most with age across the adult lifespan and that physical activity likely acts to abate detrimental change. Supplementary Information The online version contains supplementary material available at 10.1186/s12877-022-03183-4.
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Affiliation(s)
- Isobel Jacob
- Musculoskeletal Health Research Group, Leeds Beckett University, Leeds, England.
| | - Mark I Johnson
- Centre for Pain Research, Leeds Beckett University, Leeds, England
| | - Gareth Jones
- Musculoskeletal Health Research Group, Leeds Beckett University, Leeds, England
| | - Ashley Jones
- Musculoskeletal Health Research Group, Leeds Beckett University, Leeds, England
| | - Peter Francis
- Musculoskeletal Health Research Group, Leeds Beckett University, Leeds, England.,Department of Science and Health, Institute of Technology Carlow, Carlow, Ireland
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29
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Guo Y, Piasecki J, Swiecicka A, Ireland A, Phillips BE, Atherton PJ, Stashuk D, Rutter MK, McPhee JS, Piasecki M. Circulating testosterone and dehydroepiandrosterone are associated with individual motor unit features in untrained and highly active older men. GeroScience 2022; 44:1215-1228. [PMID: 34862585 PMCID: PMC9213614 DOI: 10.1007/s11357-021-00482-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/28/2021] [Indexed: 10/31/2022] Open
Abstract
Long-term exercise training has been considered as an effective strategy to counteract age-related hormonal declines and minimise muscle atrophy. However, human data relating circulating hormone levels with motor nerve function are scant. The aims of the study were to explore associations between circulating sex hormone levels and motor unit (MU) characteristics in older men, including masters athletes competing in endurance and power events. Forty-three older men (mean ± SD age: 69.9 ± 4.6 years) were studied based on competitive status. The serum concentrations of dehydroepiandrosterone (DHEA), total testosterone (T) and estradiol were quantified using liquid chromatography mass spectrometry. Intramuscular electromyographic signals were recorded from vastus lateralis (VL) during 25% of maximum voluntary isometric contractions and processed to extract MU firing rate (FR), and motor unit potential (MUP) features. After adjusting for athletic status, MU FR was positively associated with DHEA levels (p = 0.019). Higher testosterone and estradiol were associated with lower MUP complexity; these relationships remained significant after adjusting for athletic status (p = 0.006 and p = 0.019, respectively). Circulating DHEA was positively associated with MU firing rate in these older men. Higher testosterone levels were associated with reduced MUP complexity, indicating reduced electrophysiological temporal dispersion, which is related to decreased differences in conduction times along axonal branches and/or MU fibres. Although evident in males only, this work highlights the potential of hormone administration as a therapeutic interventional strategy specifically targeting human motor units in older age.
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Affiliation(s)
- Yuxiao Guo
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, School of Medicine, University of Nottingham, Nottingham, UK
| | - Jessica Piasecki
- Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement Research Centre, Nottingham Trent University, Nottingham, UK
| | - Agnieszka Swiecicka
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- Department of Basic and Clinical Sciences, University of Nicosia Medical School, Nicosia, Cyprus
| | - Alex Ireland
- Department of Sport and Exercise Sciences, Musculoskeletal Science and Sports Medicine Research Centre, Manchester Metropolitan University, Manchester, UK
| | - Bethan E. Phillips
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, School of Medicine, University of Nottingham, Nottingham, UK
| | - Philip J. Atherton
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, School of Medicine, University of Nottingham, Nottingham, UK
| | - Daniel Stashuk
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON Canada
| | - Martin K. Rutter
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- Diabetes, Endocrinology and Metabolism Centre, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - Jamie S. McPhee
- Department of Sport and Exercise Sciences, Musculoskeletal Science and Sports Medicine Research Centre, Manchester Metropolitan University, Manchester, UK
| | - Mathew Piasecki
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, School of Medicine, University of Nottingham, Nottingham, UK
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30
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Guo Y, Jones EJ, Inns TB, Ely IA, Stashuk DW, Wilkinson DJ, Smith K, Piasecki J, Phillips BE, Atherton PJ, Piasecki M. Neuromuscular recruitment strategies of the vastus lateralis according to sex. Acta Physiol (Oxf) 2022; 235:e13803. [PMID: 35184382 PMCID: PMC9286427 DOI: 10.1111/apha.13803] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 02/03/2022] [Accepted: 02/16/2022] [Indexed: 12/19/2022]
Abstract
AIM Despite males typically exhibiting greater muscle strength and fatigability than females, it remains unclear if there are sex-based differences in neuromuscular recruitment strategies e.g. recruitment and modulation of motor unit firing rate (MU FR) at normalized forces and during progressive increases in force. METHODS The study includes 29 healthy male and 31 healthy female participants (18-35 years). Intramuscular electromyography (iEMG) was used to record individual motor unit potentials (MUPs) and near-fibre MUPs from the vastus lateralis (VL) during 10% and 25% maximum isometric voluntary contractions (MVC), and spike-triggered averaging was used to obtain motor unit number estimates (MUNE) of the VL. RESULTS Males exhibited greater muscle strength (P < .001) and size (P < .001) than females, with no difference in force steadiness at 10% or 25% MVC. Females had 8.4% and 6.5% higher FR at 10% and 25% MVC, respectively (both P < .03), while the MUP area was 33% smaller in females at 10% MVC (P < .02) and 26% smaller at 25% MVC (P = .062). However, both sexes showed similar increases in MU size and FR when moving from low- to mid-level contractions. There were no sex differences in any near-fibre MUP parameters or in MUNE. CONCLUSION In the vastus lateralis, females produce muscle force via different neuromuscular recruitment strategies to males which is characterized by smaller MUs discharging at higher rates. However, similar strategies are employed to increase force production from low- to mid-level contractions. These findings of similar proportional increases between sexes support the use of mixed sex cohorts in studies of this nature.
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Affiliation(s)
- Yuxiao Guo
- Centre of Metabolism Ageing & Physiology (COMAP) MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre School of Medicine University of Nottingham Derby UK
| | - Eleanor J. Jones
- Centre of Metabolism Ageing & Physiology (COMAP) MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre School of Medicine University of Nottingham Derby UK
| | - Thomas B. Inns
- Centre of Metabolism Ageing & Physiology (COMAP) MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre School of Medicine University of Nottingham Derby UK
| | - Isabel A. Ely
- Centre of Metabolism Ageing & Physiology (COMAP) MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre School of Medicine University of Nottingham Derby UK
| | - Daniel W. Stashuk
- Department of Systems Design Engineering University of Waterloo Waterloo Ontario Canada
| | - Daniel J. Wilkinson
- Centre of Metabolism Ageing & Physiology (COMAP) MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre School of Medicine University of Nottingham Derby UK
| | - Kenneth Smith
- Centre of Metabolism Ageing & Physiology (COMAP) MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre School of Medicine University of Nottingham Derby UK
| | - Jessica Piasecki
- Musculoskeletal Physiology Research Group Sport, Health and Performance Enhancement Research Centre Nottingham Trent University Nottingham UK
| | - Bethan E. Phillips
- Centre of Metabolism Ageing & Physiology (COMAP) MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre School of Medicine University of Nottingham Derby UK
| | - Philip J. Atherton
- Centre of Metabolism Ageing & Physiology (COMAP) MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre School of Medicine University of Nottingham Derby UK
| | - Mathew Piasecki
- Centre of Metabolism Ageing & Physiology (COMAP) MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research and National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre School of Medicine University of Nottingham Derby UK
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31
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Bårdstu HB, Andersen V, Fimland MS, Raastad T, Saeterbakken AH. Muscle Strength Is Associated With Physical Function in Community-Dwelling Older Adults Receiving Home Care. A Cross-Sectional Study. Front Public Health 2022; 10:856632. [PMID: 35548065 PMCID: PMC9081336 DOI: 10.3389/fpubh.2022.856632] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 03/28/2022] [Indexed: 11/13/2022] Open
Abstract
Background Higher maximal- and explosive strength is associated with better physical function among older adults. Although the relationship between isometric maximal strength and physical function has been examined, few studies have included measures of isometric rate of force development (RFD) as a measure of explosive strength. Furthermore, little is known about the oldest old (>80 years), especially individuals who receive home care and use mobility devices. Therefore, the aim of this study was to examine the association between maximal- and explosive muscle strength with physical function in community-dwelling older adults receiving home care. Methods An exploratory cross-sectional analysis including 107 (63 females and 43 males) community-dwelling older adults [median age 86 (interquartile range 80–90) years] receiving home care was conducted. Physical function was measured with five times sit-to-stand (5TSTS), timed 8-feet-up-and-go (TUG-8ft), preferred-, and maximal gait speed. Maximal strength was assessed as maximal isometric voluntary contraction (MVC) and explosive strength as RFD of the knee extensors. We used linear regression to examine the associations, with physical function as dependent variables and muscle strength (MVC and RFD) as independent variables. Results MVC was significantly associated with 5TSST [standardized regression coefficient β = −0.26 95% CI (−0.45, −0.06)], TUG-8ft [−0.6 (−0.54, −0.17)], preferred gait speed [0.39 (0.22, 0.57)], and maximal gait speed [0.45 (0.27, 0.62)]. RFD was significantly associated with 5TSST [−0.35 (−0.54, −0.17)], TUG-8ft [−0.43 (−0.60, −0.27)], preferred gait speed [0.40 (0.22, 0.57)], and maximal gait speed [0.48 (0.31, 0.66)]. Conclusions Higher maximal- and explosive muscle strength was associated with better physical function in older adults receiving home care. Thus, maintaining and/or improving muscle strength is important for perseverance of physical function into old age and should be a priority.
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Affiliation(s)
- Hilde Bremseth Bårdstu
- Department of Sport, Food and Natural Sciences, Faculty of Education, Arts and Sports, Western Norway University of Applied Sciences, Sogndal, Norway
- Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
- *Correspondence: Hilde Bremseth Bårdstu ;
| | - Vidar Andersen
- Department of Sport, Food and Natural Sciences, Faculty of Education, Arts and Sports, Western Norway University of Applied Sciences, Sogndal, Norway
| | - Marius Steiro Fimland
- Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
- Unicare Helsefort Rehabilitation Centre, Rissa, Norway
| | - Truls Raastad
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Atle Hole Saeterbakken
- Department of Sport, Food and Natural Sciences, Faculty of Education, Arts and Sports, Western Norway University of Applied Sciences, Sogndal, Norway
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Esen O, Faisal A, Zambolin F, Bailey SJ, Callaghan MJ. Effect of nitrate supplementation on skeletal muscle motor unit activity during isometric blood flow restriction exercise. Eur J Appl Physiol 2022; 122:1683-1693. [PMID: 35460359 PMCID: PMC9197866 DOI: 10.1007/s00421-022-04946-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 03/17/2022] [Indexed: 12/26/2022]
Abstract
Background Nitrate (NO3−) supplementation has been reported to lower motor unit (MU) firing rate (MUFR) during dynamic resistance exercise; however, its impact on MU activity during isometric and ischemic exercise is unknown. Purpose To assess the effect of NO3− supplementation on knee extensor MU activities during brief isometric contractions and a 3 min sustained contraction with blood flow restriction (BFR). Methods Sixteen healthy active young adults (six females) completed two trials in a randomized, double-blind, crossover design. Trials were preceded by 5 days of either NO3− (NIT) or placebo (PLA) supplementation. Intramuscular electromyography was used to determine the M. vastus lateralis MU potential (MUP) size, MUFR and near fibre (NF) jiggle (a measure of neuromuscular stability) during brief (20 s) isometric contractions at 25% maximal strength and throughout a 3 min sustained BFR isometric contraction. Results Plasma nitrite (NO2−) concentration was elevated after NIT compared to PLA (475 ± 93 vs. 198 ± 46 nmol L−1, p < 0.001). While changes in MUP area, NF jiggle and MUFR were similar between NIT and PLA trials (all p > 0.05), MUP duration was shorter with NIT compared to PLA during brief isometric contractions and the sustained ischemic contraction (p < 0.01). In addition, mean MUP duration, MUP area and NF jiggle increased, and MUFR decreased over the 3 min sustained BFR isometric contraction for both conditions (all p < 0.05). Conclusions These findings provide insight into the effect of NO3− supplementation on MUP properties and reveal faster MUP duration after short-term NO3− supplementation which may have positive implications for skeletal muscle contractile performance.
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Affiliation(s)
- Ozcan Esen
- Department of Health Professions, Manchester Metropolitan University, Manchester, M15 6GX, UK.
- Manchester Metropolitan University Institute of Sport, Manchester, UK.
| | - Azmy Faisal
- Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, UK
- Manchester Metropolitan University Institute of Sport, Manchester, UK
- Faculty of Physical Education for Men, Alexandria University, Alexandria, Egypt
| | - Fabio Zambolin
- Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, UK
- Manchester Metropolitan University Institute of Sport, Manchester, UK
| | - Stephen J Bailey
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Michael J Callaghan
- Department of Health Professions, Manchester Metropolitan University, Manchester, M15 6GX, UK
- Manchester University Hospital Foundation Trust, Manchester, UK
- Arthritis Research UK Centre for Epidemiology, Centre for Musculoskeletal Research, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
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Fasullo M, Omer E, Kaspar M. Sarcopenia in Chronic Pancreatitis - Prevalence, Diagnosis, Mechanisms and Potential Therapies. Curr Gastroenterol Rep 2022; 24:53-63. [PMID: 35167003 DOI: 10.1007/s11894-022-00837-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
PURPOSE OF REVIEW To investigate the prevalence, pathogenesis, diagnosis, clinical sequelae, and management of sarcopenia to improve mortality and quality of life in those with Chronic Pancreatitis. RECENT FINDINGS Sarcopenia is prevalent in chronic pancreatitis and can significantly affect clinical outcomes. Sarcopenia is prevalent in chronic pancreatitis. While effects on some clinical outcomes is has been shown, there is a significant gap in knowledge regarding effects on outcomes, pathophysiology, and options for management.
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Affiliation(s)
- Matthew Fasullo
- Division of Gastroenterology, Hepatology, and Nutrition, Virginia Commonwealth University (VCU), Richmond, VA, USA
| | - Endashaw Omer
- Division of Gastroenterology, Hepatology, and Nutrition, University of Louisville, Louisville, KY, USA
| | - Matthew Kaspar
- Division of Gastroenterology, Hepatology, and Nutrition, Virginia Commonwealth University (VCU), Richmond, VA, USA.
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34
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Jones EJ, Chiou S, Atherton PJ, Phillips BE, Piasecki M. Ageing and exercise-induced motor unit remodelling. J Physiol 2022; 600:1839-1849. [PMID: 35278221 PMCID: PMC9314090 DOI: 10.1113/jp281726] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 02/14/2022] [Indexed: 11/08/2022] Open
Abstract
A motor unit (MU) comprises the neuron cell body, its corresponding axon and each of the muscle fibres it innervates. Many studies highlight age-related reductions in the number of MUs, yet the ability of a MU to undergo remodelling and to expand to rescue denervated muscle fibres is also a defining feature of MU plasticity. Remodelling of MUs involves two coordinated processes: (i) axonal sprouting and new branching growth from adjacent surviving neurons, and (ii) the formation of key structures around the neuromuscular junction to resume muscle-nerve communication. These processes rely on neurotrophins and coordinated signalling in muscle-nerve interactions. To date, several neurotrophins have attracted focus in animal models, including brain-derived neurotrophic factor and insulin-like growth factors I and II. Exercise in older age has demonstrated benefits in multiple physiological systems including skeletal muscle, yet evidence suggests this may also extend to peripheral MU remodelling. There is, however, a lack of research in humans due to methodological limitations which are easily surmountable in animal models. To improve mechanistic insight of the effects of exercise on MU remodelling with advancing age, future research should focus on combining methodological approaches to explore the in vivo physiological function of the MU alongside alterations of the localised molecular environment.
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Affiliation(s)
- Eleanor J. Jones
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC–Versus Arthritis Centre of Excellence for Musculoskeletal Ageing ResearchNottingham NIHR Biomedical Research CentreSchool of MedicineUniversity of NottinghamNottinghamUK
| | - Shin‐Yi Chiou
- School of SportExercise, and Rehabilitation Sciences, MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research, Centre for Human Brain HealthUniversity of BirminghamBirminghamUK
| | - Philip J. Atherton
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC–Versus Arthritis Centre of Excellence for Musculoskeletal Ageing ResearchNottingham NIHR Biomedical Research CentreSchool of MedicineUniversity of NottinghamNottinghamUK
| | - Bethan E. Phillips
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC–Versus Arthritis Centre of Excellence for Musculoskeletal Ageing ResearchNottingham NIHR Biomedical Research CentreSchool of MedicineUniversity of NottinghamNottinghamUK
| | - Mathew Piasecki
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC–Versus Arthritis Centre of Excellence for Musculoskeletal Ageing ResearchNottingham NIHR Biomedical Research CentreSchool of MedicineUniversity of NottinghamNottinghamUK
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Coletti C, Acosta GF, Keslacy S, Coletti D. Exercise-mediated reinnervation of skeletal muscle in elderly people: An update. Eur J Transl Myol 2022; 32. [PMID: 35234025 PMCID: PMC8992679 DOI: 10.4081/ejtm.2022.10416] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 02/17/2022] [Indexed: 11/22/2022] Open
Abstract
Sarcopenia is defined by the loss of muscle mass and function. In aging sarcopenia is due to mild chronic inflammation but also to fiber-intrinsic defects, such as mitochondrial dysfunction. Age-related sarcopenia is associated with physical disability and lowered quality of life. In addition to skeletal muscle, the nervous tissue is also affected in elderly people. With aging, type 2 fast fibers preferentially undergo denervation and are reinnervated by slow-twitch motor neurons. They spread forming new neuro-muscular junctions with the denervated fibers: the result is an increased proportion of slow fibers that group together since they are associated in the same motor unit. Grouping and fiber type shifting are indeed major histological features of aging skeletal muscle. Exercise has been proposed as an intervention for age-related sarcopenia due to its numerous beneficial effects on muscle mechanical and biochemical features. In 2013, a precursor study in humans was published in the European Journal of Translation Myology (formerly known as Basic and Applied Myology), highlighting the occurrence of reinnervation in the musculature of aged, exercise-trained individuals as compared to the matching control. This paper, entitled «Reinnervation of Vastus lateralis is increased significantly in seniors (70-years old) with a lifelong history of high-level exercise», is now being reprinted for the second issue of the «Ejtm Seminal Paper Series». In this short review we discuss those results in the light of the most recent advances confirming the occurrence of exercise-mediated reinnervation, ultimately preserving muscle structure and function in elderly people who exercise.
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Affiliation(s)
- Claudia Coletti
- School of Kinesiology, Nutrition and Food Science, California State University Los Angeles, Los Angeles, CA.
| | - Gilberto F Acosta
- School of Kinesiology, Nutrition and Food Science, California State University Los Angeles, Los Angeles, CA.
| | - Stefan Keslacy
- School of Kinesiology, Nutrition and Food Science, California State University Los Angeles, Los Angeles, CA.
| | - Dario Coletti
- DAHFMO - Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy; Biological Adaptation and Ageing, CNRS UMR 8256, Inserm U1164, Institut de Biologie Paris-Seine, Sorbonne Université, Paris, France; Interuniversity institute of Myology, Ro.
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36
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Soendenbroe C, Dahl CL, Meulengracht C, Tamáš M, Svensson RB, Schjerling P, Kjaer M, Andersen JL, Mackey AL. Preserved stem cell content and innervation profile of elderly human skeletal muscle with lifelong recreational exercise. J Physiol 2022; 600:1969-1989. [PMID: 35229299 PMCID: PMC9315046 DOI: 10.1113/jp282677] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 02/14/2022] [Indexed: 11/21/2022] Open
Abstract
Abstract Muscle fibre denervation and declining numbers of muscle stem (satellite) cells are defining characteristics of ageing skeletal muscle. The aim of this study was to investigate the potential for lifelong recreational exercise to offset muscle fibre denervation and compromised satellite cell content and function, both at rest and under challenged conditions. Sixteen elderly lifelong recreational exercisers (LLEX) were studied alongside groups of age‐matched sedentary (SED) and young subjects. Lean body mass and maximal voluntary contraction were assessed, and a strength training bout was performed. From muscle biopsies, tissue and primary myogenic cell cultures were analysed by immunofluorescence and RT‐qPCR to assess myofibre denervation and satellite cell quantity and function. LLEX demonstrated superior muscle function under challenged conditions. When compared with SED, the muscle of LLEX was found to contain a greater content of satellite cells associated with type II myofibres specifically, along with higher mRNA levels of the beta and gamma acetylcholine receptors (AChR). No difference was observed between LLEX and SED for the proportion of denervated fibres or satellite cell function, as assessed in vitro by myogenic cell differentiation and fusion index assays. When compared with inactive counterparts, the skeletal muscle of lifelong exercisers is characterised by greater fatigue resistance under challenged conditions in vivo, together with a more youthful tissue satellite cell and AChR profile. Our data suggest a little recreational level exercise goes a long way in protecting against the emergence of classic phenotypic traits associated with the aged muscle. Key points The detrimental effects of ageing can be partially offset by lifelong self‐organized recreational exercise, as evidence by preserved type II myofibre‐associated satellite cells, a beneficial muscle innervation status and greater fatigue resistance under challenged conditions. Satellite cell function (in vitro), muscle fibre size and muscle fibre denervation determined by immunofluorescence were not affected by recreational exercise. Individuals that are recreationally active are far more abundant than master athletes, which sharply increases the translational perspective of the present study. Future studies should further investigate recreational activity in relation to muscle health, while also including female participants.
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Affiliation(s)
- Casper Soendenbroe
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Building 8, Nielsine Nielsens vej 11, Copenhagen, NV, 2400, Denmark.,Xlab, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen N, 2200, Denmark.,Center for Healthy Aging, Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen N, 2200, Denmark
| | - Christopher L Dahl
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Building 8, Nielsine Nielsens vej 11, Copenhagen, NV, 2400, Denmark
| | - Christopher Meulengracht
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Building 8, Nielsine Nielsens vej 11, Copenhagen, NV, 2400, Denmark
| | - Michal Tamáš
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Building 8, Nielsine Nielsens vej 11, Copenhagen, NV, 2400, Denmark
| | - Rene B Svensson
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Building 8, Nielsine Nielsens vej 11, Copenhagen, NV, 2400, Denmark.,Center for Healthy Aging, Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen N, 2200, Denmark
| | - Peter Schjerling
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Building 8, Nielsine Nielsens vej 11, Copenhagen, NV, 2400, Denmark.,Center for Healthy Aging, Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen N, 2200, Denmark
| | - Michael Kjaer
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Building 8, Nielsine Nielsens vej 11, Copenhagen, NV, 2400, Denmark.,Center for Healthy Aging, Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen N, 2200, Denmark
| | - Jesper L Andersen
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Building 8, Nielsine Nielsens vej 11, Copenhagen, NV, 2400, Denmark.,Center for Healthy Aging, Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen N, 2200, Denmark
| | - Abigail L Mackey
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Building 8, Nielsine Nielsens vej 11, Copenhagen, NV, 2400, Denmark.,Xlab, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen N, 2200, Denmark.,Center for Healthy Aging, Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen N, 2200, Denmark
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Orssatto LBR, Borg DN, Pendrith L, Blazevich AJ, Shield AJ, Trajano GS. DO MOTONEURON DISCHARGE RATES SLOW WITH AGING? A SYSTEMATIC REVIEW AND META-ANALYSIS. Mech Ageing Dev 2022; 203:111647. [PMID: 35218849 DOI: 10.1016/j.mad.2022.111647] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/03/2022] [Accepted: 02/21/2022] [Indexed: 11/30/2022]
Abstract
Nervous system maladaptation is linked to the loss of maximal strength and motor control with aging. Motor unit discharge rates are a critical determinant of force production; thus, lower discharge rates could be a mechanism underpinning maximal strength and motor control losses during aging. This meta-analysis summarized the findings of studies comparing motor unit discharge rates between young and older adults, and examined the effects of the selected muscle and contraction intensity on the magnitude of discharge rates difference between these two groups. Estimates from 29 studies, across a range of muscles and contraction intensities, were combined in a multilevel meta-analysis, to investigate whether discharge rates differed between young and older adults. Motor unit discharge rates were higher in younger than older adults, with a pooled standardized mean difference (SMD) of 0.66 (95%CI= 0.29-1.04). Contraction intensity had a significant effect on the pooled SMD, with a 1% increase in intensity associated with a 0.009 (95%CI= 0.003-0.015) change in the pooled SMD. These findings suggest that reductions in motor unit discharge rates, especially at higher contraction intensities, may be an important mechanism underpinning age-related losses in maximal force production.
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Affiliation(s)
- Lucas B R Orssatto
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Australia.
| | - David N Borg
- Griffith University, Menzies Health Institute Queensland, The Hopkins Centre, Brisbane, Australia
| | - Linda Pendrith
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Australia
| | - Anthony J Blazevich
- Centre for Human Performance, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia
| | - Anthony J Shield
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Australia
| | - Gabriel S Trajano
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Australia
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Staunton CA, Owen ED, Hemmings K, Vasilaki A, McArdle A, Barrett-Jolley R, Jackson MJ. Skeletal muscle transcriptomics identifies common pathways in nerve crush injury and ageing. Skelet Muscle 2022; 12:3. [PMID: 35093178 PMCID: PMC8800362 DOI: 10.1186/s13395-021-00283-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 11/24/2021] [Indexed: 12/16/2022] Open
Abstract
Motor unit remodelling involving repeated denervation and re-innervation occurs throughout life. The efficiency of this process declines with age contributing to neuromuscular deficits. This study investigated differentially expressed genes (DEG) in muscle following peroneal nerve crush to model motor unit remodelling in C57BL/6 J mice. Muscle RNA was isolated at 3 days post-crush, RNA libraries were generated using poly-A selection, sequenced and analysed using gene ontology and pathway tools. Three hundred thirty-four DEG were found in quiescent muscle from (26mnth) old compared with (4-6mnth) adult mice and these same DEG were present in muscle from adult mice following nerve crush. Peroneal crush induced 7133 DEG in muscles of adult and 699 DEG in muscles from old mice, although only one DEG (ZCCHC17) was found when directly comparing nerve-crushed muscles from old and adult mice. This analysis revealed key differences in muscle responses which may underlie the diminished ability of old mice to repair following nerve injury.
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Affiliation(s)
- C A Staunton
- MRC- Versus Arthritis Research Centre for Integrated research into Musculoskeletal Ageing (CIMA), Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L7 8TX, UK
| | - E D Owen
- MRC- Versus Arthritis Research Centre for Integrated research into Musculoskeletal Ageing (CIMA), Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L7 8TX, UK
| | - K Hemmings
- MRC- Versus Arthritis Research Centre for Integrated research into Musculoskeletal Ageing (CIMA), Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L7 8TX, UK
| | - A Vasilaki
- MRC- Versus Arthritis Research Centre for Integrated research into Musculoskeletal Ageing (CIMA), Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L7 8TX, UK
| | - A McArdle
- MRC- Versus Arthritis Research Centre for Integrated research into Musculoskeletal Ageing (CIMA), Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L7 8TX, UK
| | - R Barrett-Jolley
- MRC- Versus Arthritis Research Centre for Integrated research into Musculoskeletal Ageing (CIMA), Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L7 8TX, UK
| | - M J Jackson
- MRC- Versus Arthritis Research Centre for Integrated research into Musculoskeletal Ageing (CIMA), Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L7 8TX, UK.
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Ronaldson SM, Stephenson DG, Head SI. Calcium and strontium contractile activation properties of single skinned skeletal muscle fibres from elderly women 66-90 years of age. J Muscle Res Cell Motil 2022; 43:173-183. [PMID: 35987933 PMCID: PMC9708809 DOI: 10.1007/s10974-022-09628-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/01/2022] [Indexed: 12/31/2022]
Abstract
The single freshly skinned muscle fibre technique was used to investigate Ca2+- and Sr2+-activation properties of skeletal muscle fibres from elderly women (66-90 years). Muscle biopsies were obtained from the vastus lateralis muscle. Three populations of muscle fibres were identified according to their specific Sr2+-activation properties: slow-twitch (type I), fast-twitch (type II) and hybrid (type I/II) fibres. All three fibre types were sampled from the biopsies of 66 to 72 years old women, but the muscle biopsies of women older than 80 years yielded only slow-twitch (type I) fibres. The proportion of hybrid fibres in the vastus lateralis muscle of women of circa 70 years of age (24%) was several-fold greater than in the same muscle of adults (< 10%), suggesting that muscle remodelling occurs around this age. There were no differences between the Ca2+- and Sr2+-activation properties of slow-twitch fibres from the two groups of elderly women, but there were differences compared with muscle fibres from young adults with respect to sensitivity to Ca2+, steepness of the activation curves, and characteristics of the fibre-type dependent phenomenon of spontaneous oscillatory contractions (SPOC) (or force oscillations) occurring at submaximal levels of activation. The maximal Ca2+ activated specific force from all the fibres collected from the seven old women use in the present study was significantly lower by 20% than in the same muscle of adults. Taken together these results show there are qualitative and quantitative changes in the activation properties of the contractile apparatus of muscle fibres from the vastus lateralis muscle of women with advancing age, and that these changes need to be considered when explaining observed changes in women's mobility with aging.
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Affiliation(s)
| | - D. George Stephenson
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, 3086 Australia
| | - Stewart I. Head
- School of Medicine, Western Sydney University, Sydney, 2751 Australia ,Chair of Physiology, School of Medicine, Western Sydney University, Sydney, NSW 2751 Australia
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Jofré-Saldía E, Villalobos-Gorigoitía Á, Gea-García G. Methodological Proposal for Strength and Power Training in Older Athletes: A Narrative Review. Curr Aging Sci 2022; 15:135-146. [PMID: 35227189 DOI: 10.2174/1874609815666220228153646] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 11/08/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
INTRODUCTION Within the adult population, it is not uncommon to meet older athletes who challenge the negative stereotypes associated with aging. Although their physical performance is superior to their sedentary counterparts, they are not immune to impaired neuromuscular function, leading to a decreased physical capacity and an increased risk of injuries. Despite the abundant information about the benefits of strength/power training in advanced ages, there are no methodological proposals that guide physical activity professionals to program this type of training. OBJECTIVE This study aimed to review the factors related to the decrease in sports performance within older athletes and the benefits of a strength/power program in order to provide a methodological proposal to organize training in this population. METHODS This is a review article. First, databases from PubMed, Science Direct, and SPORTSDiscus and search engines, namely Google Scholar and Scielo, were reviewed, using standard keywords such as strength and power training, evaluation of physical performance, neuromuscular function, and risk of injury in the elderly athlete. All related articles published during the period 1963 to 2020 were considered. A total of 1837 documents were found. By removing 1715 unrelated documents, 122 articles were included in the study after revision control. RESULTS Strength/power training is key to alleviating the loss of performance in older athletes and the benefits in neuromuscular function, which helps reduce the rate of serious injuries, maintaining sports practice for a longer period of time. In order to design an appropriate program, a prior evaluation of the individual's physical-technical level must be carried out, respecting the biologicalpedagogical principles and safety regulations. CONCLUSION The methodological proposal delivered in this review can serve as a technical guide for physical activity professionals, which will be able to structure the strength/power training and thus preserve the sports practice in older athletes for a longer time.
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Affiliation(s)
- Emilio Jofré-Saldía
- Instituto del Deporte, Universidad de las Américas, Santiago, Chile
- Departamento de Ciencias de la Actividad Física y el Deporte, Facultad de Deporte, Universidad Católica San Antonio de Murcia, Murcia, España
| | | | - Gemma Gea-García
- Departamento de Ciencias de la Actividad Física y el Deporte, Facultad de Deporte, Universidad Católica San Antonio de Murcia, Murcia, España
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Patterns of Movement Performance and Consistency From Childhood to Old Age. Motor Control 2022; 27:258-274. [PMID: 36351427 DOI: 10.1123/mc.2022-0006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 09/01/2022] [Accepted: 09/07/2022] [Indexed: 11/11/2022]
Abstract
It is widely accepted that the general process of aging can be reflected by changes in motor function. Typically, optimal performance of a given motor task is observed for healthy young adults with declines being observed for individuals at either end of the lifespan. This study was designed to examine differences in the average and variability (i.e., intraindividual variability) of chewing, simple reaction time, postural control, and walking responses. For this study, 15 healthy children, 15 young adults, and 15 older adults participated. Our results indicated the movement performance for the reaction time and postural sway followed a U shape with young adults having faster reaction times and decreased postural sway compared to the children and older adults. However, this pattern was not preserved across all motor tasks with no age differences emerging for (normalized) gait speed, while chewing rates followed a U-shaped curve with older adults and children chewing at faster rates. Taken together, these findings would indicate that the descriptive changes in motor function with aging are heavily influenced by the nature of the task being performed and are unlikely to follow a singular pattern.
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Pethick J, Piasecki M. Alterations in Muscle Force Control With Aging: Is There a Modulatory Effect of Lifelong Physical Activity? Front Sports Act Living 2022; 4:817770. [PMID: 35392594 PMCID: PMC8980913 DOI: 10.3389/fspor.2022.817770] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 02/28/2022] [Indexed: 11/16/2022] Open
Abstract
Recent technological developments have enabled significant advances in our understanding of the ability to voluntarily control muscle force output. The fluctuations inherent to muscle force output can be quantified according to both their magnitude and temporal structure (or "complexity"), with such quantification facilitating comparison of force control between distinct populations. In comparison to young adults, older adults exhibit an increase in the magnitude (i.e., decreased steadiness) and a decrease in the complexity (i.e., decreased adaptability) of force fluctuations, both of which are indicative of a loss of force control. There remain, however, key gaps in knowledge that limit our interpretation of this age-related loss of force control. One such gap relates to the effect of lifelong physical activity on force control. To date, research on aging and force control has largely been conducted on inactive or moderately active older adults. However, high levels of lifelong physical activity, such as that exhibited by Masters athletes, have been shown to have protective effects on the function and morphology of the neuromuscular system. Some of these effects (e.g., on impaired inhibitory transmission in the motor cortex and on motor unit discharge rates) have the potential to attenuate the age-related loss of force control, while others (e.g., greater motor unit remodeling capacity) have the potential to worsen it. We therefore propose that, in order to progress our knowledge of the effects of aging on force control, future studies must consider the potential modulatory effect of lifelong physical activity.
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Affiliation(s)
- Jamie Pethick
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Colchester, United Kingdom
- *Correspondence: Jamie Pethick
| | - Mathew Piasecki
- Centre of Metabolism, Ageing and Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Nottingham, United Kingdom
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Wu R, De Vito G, Lowery MM, O'Callaghan B, Ditroilo M. Age-related fatigability in knee extensors and knee flexors during dynamic fatiguing contractions. J Electromyogr Kinesiol 2021; 62:102626. [PMID: 34998161 DOI: 10.1016/j.jelekin.2021.102626] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 11/08/2021] [Accepted: 12/14/2021] [Indexed: 12/01/2022] Open
Abstract
This study investigated the effects of dynamic knee extension and flexion fatiguing task on torque and neuromuscular responses in young and older individuals. Eighteen young (8 males; 25.1 ± 3.2 years) and 17 older (8 males; 69.7 ± 3.7 years) volunteered. Following a maximal voluntary isometric contraction test, participants performed a fatiguing task involving 22 maximal isokinetic (concentric) knee extension and flexion contractions at 60°/s, while surface EMG was recorded simultaneously from the knee extensors (KE) and flexors (KF). Fatigue-induced relative torque reductions were similar between age groups for KE (peak torque decrease: 25.15% vs 26.81%); however, KF torque was less affected in older individuals (young vs older peak torque decrease: 27.6% vs 11.5%; p < 0.001) and this was associated with greater increase in hamstring EMG amplitude (p < 0.001) and hamstrings/quadriceps peak torque ratio (p < 0.01). Furthermore, KE was more fatigable than KF only among older individuals (peak torque decrease: 26.8% vs 11.5%; p < 0.001). These findings showed that the age-related fatigue induced by a dynamic task was greater for the KE, with greater age-related decline in KE compared to KF.
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Affiliation(s)
- Rui Wu
- School of Electrical & Electronic Engineering, University College Dublin, Dublin, Ireland; School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland
| | - Giuseppe De Vito
- School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland; Biomedical Sciences Department, Neuromuscular Physiology Laboratory, University of Padova, Italy
| | - Madeleine M Lowery
- School of Electrical & Electronic Engineering, University College Dublin, Dublin, Ireland
| | - Ben O'Callaghan
- School of Electrical & Electronic Engineering, University College Dublin, Dublin, Ireland
| | - Massimiliano Ditroilo
- School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland
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Orssatto LBR, Borg DN, Blazevich AJ, Sakugawa RL, Shield AJ, Trajano GS. Intrinsic motoneuron excitability is reduced in soleus and tibialis anterior of older adults. GeroScience 2021; 43:2719-2735. [PMID: 34716899 PMCID: PMC8556797 DOI: 10.1007/s11357-021-00478-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 10/18/2021] [Indexed: 12/19/2022] Open
Abstract
Age-related deterioration within both motoneuron and monoaminergic systems should theoretically reduce neuromodulation by weakening motoneuronal persistent inward current (PIC) amplitude. However, this assumption remains untested. Surface electromyographic signals were collected using two 32-channel electrode matrices placed on soleus and tibialis anterior of 25 older adults (70 ± 4 years) and 17 young adults (29 ± 5 years) to investigate motor unit discharge behaviors. Participants performed triangular-shaped plantar and dorsiflexion contractions to 20% of maximum torque at a rise-decline rate of 2%/s of each participant's maximal torque. Pairwise and composite paired-motor unit analyses were adopted to calculate delta frequency (ΔF), which has been used to differentiate between the effects of synaptic excitation and intrinsic motoneuronal properties and is assumed to be proportional to PIC amplitude. Soleus and tibialis anterior motor units in older adults had lower ΔFs calculated with either the pairwise [-0.99 and -1.46 pps; -35.4 and -33.5%, respectively] or composite (-1.18 and -2.28 pps; -32.1 and -45.2%, respectively) methods. Their motor units also had lower peak discharge rates (-2.14 and -2.03 pps; -19.7 and -13.9%, respectively) and recruitment thresholds (-1.50 and -2.06% of maximum, respectively) than young adults. These results demonstrate reduced intrinsic motoneuron excitability during low-force contractions in older adults, likely mediated by decreases in the amplitude of persistent inward currents. Our findings might be explained by deterioration in the motoneuron or monoaminergic systems and could contribute to the decline in motor function during aging; these assumptions should be explicitly tested in future investigations.
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Affiliation(s)
- Lucas B. R. Orssatto
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Australia
| | - David N. Borg
- Menzies Health Institute Queensland, The Hopkins Centre, Griffith University, Brisbane, Australia
| | | | - Raphael L. Sakugawa
- Biomechanics Laboratory, Department of Physical Education, Federal University of Santa Catarina, Florianopolis, Brazil
| | - Anthony J. Shield
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Australia
| | - Gabriel S. Trajano
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Australia
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Olson LC, Redden JT, Schwartz Z, Cohen DJ, McClure MJ. Advanced Glycation End-Products in Skeletal Muscle Aging. Bioengineering (Basel) 2021; 8:bioengineering8110168. [PMID: 34821734 PMCID: PMC8614898 DOI: 10.3390/bioengineering8110168] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/26/2021] [Accepted: 10/28/2021] [Indexed: 12/17/2022] Open
Abstract
Advanced age causes skeletal muscle to undergo deleterious changes including muscle atrophy, fast-to-slow muscle fiber transition, and an increase in collagenous material that culminates in the age-dependent muscle wasting disease known as sarcopenia. Advanced glycation end-products (AGEs) non-enzymatically accumulate on the muscular collagens in old age via the Maillard reaction, potentiating the accumulation of intramuscular collagen and stiffening the microenvironment through collagen cross-linking. This review contextualizes known aspects of skeletal muscle extracellular matrix (ECM) aging, especially the role of collagens and AGE cross-linking, and underpins the motor nerve’s role in this aging process. Specific directions for future research are also discussed, with the understudied role of AGEs in skeletal muscle aging highlighted. Despite more than a half century of research, the role that intramuscular collagen aggregation and cross-linking plays in sarcopenia is well accepted yet not well integrated with current knowledge of AGE’s effects on muscle physiology. Furthermore, the possible impact that motor nerve aging has on intramuscular cross-linking and muscular AGE levels is posited.
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Affiliation(s)
- Lucas C. Olson
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA; (L.C.O.); (J.T.R.); (Z.S.); (D.J.C.)
- Department of Gerontology, College of Health Professions, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - James T. Redden
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA; (L.C.O.); (J.T.R.); (Z.S.); (D.J.C.)
| | - Zvi Schwartz
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA; (L.C.O.); (J.T.R.); (Z.S.); (D.J.C.)
- Department of Periodontics, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - David J. Cohen
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA; (L.C.O.); (J.T.R.); (Z.S.); (D.J.C.)
| | - Michael J. McClure
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA; (L.C.O.); (J.T.R.); (Z.S.); (D.J.C.)
- Correspondence:
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Hammond KG, Magrini MA, Siedlik JA, Scott Bickel C, Bamman MM. Influence of muscle fatigue on contractile twitch characteristics in persons with parkinson's disease and older adults: A pilot study. Clin Park Relat Disord 2021; 5:100103. [PMID: 34430844 PMCID: PMC8374465 DOI: 10.1016/j.prdoa.2021.100103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 08/02/2021] [Accepted: 08/03/2021] [Indexed: 11/29/2022] Open
Abstract
Introduction It is widely accepted that pathophysiological changes to the central nervous system of persons with Parkinson's disease (PD) result in negative effects on motor function. However, less information is known regarding the pathology of PD on skeletal muscle. The purpose of this study was to determine the effect of a fatiguing isometric knee extension protocol on muscle mechanics using evoked twitch contractions in persons with PD and in non-impaired older adults (OLD). Methods Evoked twitch contractions were examined during a fatiguing protocol in PD (66 ± 9 yr, n = 8) and OLD (65 ± 10 yr, n = 5). Participants performed 5-sec maximal isometric voluntary contractions of the quadriceps femoris with 5-sec rest for 3-min. Every 30-sec during rest intervals, a maximal transcutaneous electrical stimulus was administered to the quadriceps femoris to quantify evoked peak twitch torque (pTT), peak relaxation rate (pRR), and peak rate of torque development (pRTD). Results A large effect of voluntary fatigue (%decline) was observed (g = 1.58). There were no significant differences in pTT (p = 0.09; 95% CI:-3.6, 0.28) or pRR (p = 0.11; 95% CI:-31, 3.6). However, the slope decline of pRTD in OLD (-35.4 ± 24.7) was greater than PD (-11.5 ± 11.4; p = 0.03), indicating that skeletal muscle in persons with PD is less fatigable compared to non-impaired older adults. Conclusion The rate, not the maximum capacity, of torque generation of the muscle during a fatiguing knee extension protocol was affected by PD. Future studies are warranted to identify the mechanism(s) responsible for the observed differences in skeletal muscle contractile characteristics and potential myofiber distribution variation in PD.
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Affiliation(s)
- Kelley G Hammond
- Department of Exercise Science and Pre-Health Professions, Creighton University, 2500 California Plaza, Omaha, NE 68104, USA.,Dept of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham 1720 2 Ave South, Birmingham, AL 35294, USA
| | - Mitchel A Magrini
- Department of Exercise Science and Pre-Health Professions, Creighton University, 2500 California Plaza, Omaha, NE 68104, USA
| | - Jacob A Siedlik
- Department of Exercise Science and Pre-Health Professions, Creighton University, 2500 California Plaza, Omaha, NE 68104, USA
| | - C Scott Bickel
- Department of Physical Therapy, Samford University, 800 Lakeshore Pkwy, Birmingham, AL 35229, USA
| | - Marcas M Bamman
- Dept of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham 1720 2 Ave South, Birmingham, AL 35294, USA.,Florida Institute for Human and Machine Cognition, 40 South Alcaniz St, Pensacola, FL 32502, USA
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47
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Allen MD, Dalton BH, Gilmore KJ, McNeil CJ, Doherty TJ, Rice CL, Power GA. Neuroprotective effects of exercise on the aging human neuromuscular system. Exp Gerontol 2021; 152:111465. [PMID: 34224847 DOI: 10.1016/j.exger.2021.111465] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 05/31/2021] [Accepted: 06/30/2021] [Indexed: 12/23/2022]
Abstract
Human biological aging from maturity to senescence is associated with a gradual loss of muscle mass and neuromuscular function. It is not until very old age (>80 years) however, that these changes often manifest into functional impairments. A driving factor underlying the age-related loss of muscle mass and function is the reduction in the number and quality of motor units (MUs). A MU consists of a single motoneuron, located either in the spinal cord or the brain stem, and all of the muscle fibres it innervates via its peripheral axon. Throughout the adult lifespan, MUs are slowly, but progressively lost. The compensatory process of collateral reinnervation attempts to recapture orphaned muscle fibres following the death of a motoneuron. Whereas this process helps mitigate loss of muscle mass during the latter decades of adult aging, the neuromuscular system has fewer and larger MUs, which have lower quality connections between the axon terminal and innervated muscle fibres. Whether this process of MU death and degradation can be attenuated with habitual physical activity has been a challenging question of great interest. This review focuses on age-related alterations of the human neuromuscular system, with an emphasis on the MU, and presents findings on the potential protective effects of lifelong physical activity. Although there is some discrepancy across studies of masters athletes, if one considers all experimental limitations as well as the available literature in animals, there is compelling evidence of a protective effect of chronic physical training on human MUs. Our tenet is that high-levels of physical activity can mitigate the natural trajectory of loss of quantity and quality of MUs in old age.
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Affiliation(s)
- Matti D Allen
- Department of Physical Medicine and Rehabilitation, School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON K7L 4X3, Canada; School of Kinesiology and Health Studies, Faculty of Arts and Sciences, Queen's University, Kingston, ON K7L 4X3, Canada
| | - Brian H Dalton
- School of Health and Exercise Science, University of British Columbia, Kelowna, BC V1V 1V7, Canada
| | - Kevin J Gilmore
- Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Chris J McNeil
- School of Health and Exercise Science, University of British Columbia, Kelowna, BC V1V 1V7, Canada
| | - Timothy J Doherty
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada; Department of Physical Medicine and Rehabilitation, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada
| | - Charles L Rice
- School of Kinesiology, The University of Western Ontario, London, ON, Canada; Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada.
| | - Geoffrey A Power
- Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
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Schroder EA, Wang L, Wen Y, Callahan LAP, Supinski GS. Skeletal muscle-specific calpastatin overexpression mitigates muscle weakness in aging and extends life span. J Appl Physiol (1985) 2021; 131:630-642. [PMID: 34197232 DOI: 10.1152/japplphysiol.00883.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Calpain activation has been postulated as a potential contributor to the loss of muscle mass and function associated with both aging and disease, but limitations of previous experimental approaches have failed to completely examine this issue. We hypothesized that mice overexpressing calpastatin (CalpOX), an endogenous inhibitor of calpain, solely in skeletal muscle would show an amelioration of the aging muscle phenotype. We assessed four groups of mice (age in months): 1) young wild type (WT; 5.71 ± 0.43), 2) young CalpOX (5.6 ± 0.5), 3) old WT (25.81 ± 0.56), and 4) old CalpOX (25.91 ± 0.60) for diaphragm and limb muscle (extensor digitorum longus, EDL) force frequency relations. Aging significantly reduced diaphragm and EDL peak force in old WT mice, and decreased the force-time integral during a fatiguing protocol by 48% and 23% in aged WT diaphragm and EDL, respectively. In contrast, we found that CalpOX mice had significantly increased diaphragm and EDL peak force in old mice, similar to that observed in young mice. The impact of aging on the force-time integral during a fatiguing protocol was abolished in the diaphragm and EDL of old CalpOX animals. Surprisingly, we found that CalpOX had a significant impact on longevity, increasing median survival from 20.55 mo in WT mice to 24 mo in CalpOX mice (P = 0.0006).NEW & NOTEWORTHY This is the first study to investigate the role of calpastatin overexpression on skeletal muscle specific force in aging rodents. Muscle-specific overexpression of calpastatin, the endogenous calpain inhibitor, prevented aging-induced reductions in both EDL and diaphragm specific force and, remarkably, increased life span. These data suggest that diaphragm dysfunction in aging may be a major factor in determining longevity. Targeting the calpain/calpastatin pathway may elucidate novel therapies to combat skeletal muscle weakness in aging.
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Affiliation(s)
- Elizabeth A Schroder
- Pulmonary Division, Department of Internal Medicine, University of Kentucky, Lexington, Kentucky.,Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky.,Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
| | - Lin Wang
- Pulmonary Division, Department of Internal Medicine, University of Kentucky, Lexington, Kentucky
| | - Yuan Wen
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky.,Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
| | - Leigh Ann P Callahan
- Pulmonary Division, Department of Internal Medicine, University of Kentucky, Lexington, Kentucky.,Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
| | - Gerald S Supinski
- Pulmonary Division, Department of Internal Medicine, University of Kentucky, Lexington, Kentucky.,Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
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McKendry J, Stokes T, Mcleod JC, Phillips SM. Resistance Exercise, Aging, Disuse, and Muscle Protein Metabolism. Compr Physiol 2021; 11:2249-2278. [PMID: 34190341 DOI: 10.1002/cphy.c200029] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Skeletal muscle is the organ of locomotion, its optimal function is critical for athletic performance, and is also important for health due to its contribution to resting metabolic rate and as a site for glucose uptake and storage. Numerous endogenous and exogenous factors influence muscle mass. Much of what is currently known regarding muscle protein turnover is owed to the development and use of stable isotope tracers. Skeletal muscle mass is determined by the meal- and contraction-induced alterations of muscle protein synthesis and muscle protein breakdown. Increased loading as resistance training is the most potent nonpharmacological strategy by which skeletal muscle mass can be increased. Conversely, aging (sarcopenia) and muscle disuse lead to the development of anabolic resistance and contribute to the loss of skeletal muscle mass. Nascent omics-based technologies have significantly improved our understanding surrounding the regulation of skeletal muscle mass at the gene, transcript, and protein levels. Despite significant advances surrounding the mechanistic intricacies that underpin changes in skeletal muscle mass, these processes are complex, and more work is certainly needed. In this article, we provide an overview of the importance of skeletal muscle, describe the influence that resistance training, aging, and disuse exert on muscle protein turnover and the molecular regulatory processes that contribute to changes in muscle protein abundance. © 2021 American Physiological Society. Compr Physiol 11:2249-2278, 2021.
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Affiliation(s)
- James McKendry
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Tanner Stokes
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Jonathan C Mcleod
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Stuart M Phillips
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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50
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Padilla CJ, Harrigan ME, Harris H, Schwab JM, Rutkove SB, Rich MM, Clark BC, Arnold WD. Profiling age-related muscle weakness and wasting: neuromuscular junction transmission as a driver of age-related physical decline. GeroScience 2021; 43:1265-1281. [PMID: 33895959 PMCID: PMC8190265 DOI: 10.1007/s11357-021-00369-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/19/2021] [Indexed: 12/22/2022] Open
Abstract
Pathological age-related loss of skeletal muscle strength and mass contribute to impaired physical function in older adults. Factors that promote the development of these conditions remain incompletely understood, impeding development of effective and specific diagnostic and therapeutic approaches. Inconclusive evidence across species suggests disruption of action potential signal transmission at the neuromuscular junction (NMJ), the crucial connection between the nervous and muscular systems, as a possible contributor to age-related muscle dysfunction. Here we investigated age-related loss of NMJ function using clinically relevant, electrophysiological measures (single-fiber electromyography (SFEMG) and repetitive nerve stimulation (RNS)) in aged (26 months) versus young (6 months) F344 rats. Measures of muscle function (e.g., grip strength, peak plantarflexion contractility torque) and mass were assessed for correlations with physiological measures (e.g., indices of NMJ transmission). Other outcomes also included plantarflexion muscle contractility tetanic torque fade during 1-s trains of stimulation as well as gastrocnemius motor unit size and number. Profiling NMJ function in aged rats identified significant declines in NMJ transmission stability and reliability. Further, NMJ deficits were tightly correlated with hindlimb grip strength, gastrocnemius muscle weight, loss of peak contractility torque, degree of tetanic fade, and motor unit loss. Thus, these findings provide direct evidence for NMJ dysfunction as a potential mechanism of age-related muscle dysfunction pathogenesis and severity. These findings also suggest that NMJ transmission modulation may serve as a target for therapeutic development for age-related loss of physical function.
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Affiliation(s)
- Carlos J Padilla
- Division of Neuromuscular Diseases, Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Room 207, Columbus, OH, 43210, USA
| | - Markus E Harrigan
- Division of Neuromuscular Diseases, Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Room 207, Columbus, OH, 43210, USA
| | - Hallie Harris
- Division of Neuromuscular Diseases, Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Room 207, Columbus, OH, 43210, USA
| | - Jan M Schwab
- Division of Neuromuscular Diseases, Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Room 207, Columbus, OH, 43210, USA
- Belford Center for Spinal Cord Injury, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Physical Medicine and Rehabilitation, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Center for Brain and Spinal Cord Repair, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- The Neurological Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
- Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Seward B Rutkove
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Mark M Rich
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, 45435, USA
| | - Brian C Clark
- Department of Biomedical Sciences, Ohio Musculoskeletal and Neurological Institute, Athens, OH, 45701, USA
| | - W David Arnold
- Division of Neuromuscular Diseases, Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Room 207, Columbus, OH, 43210, USA.
- Department of Physical Medicine and Rehabilitation, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
- The Neurological Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
- Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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