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Hayman O, Combet E, Witard OC, Gray SR. Long-chain n-3 polyunsaturated fatty acid supplementation and neuromuscular function in older adults. Curr Opin Clin Nutr Metab Care 2024:00075197-990000000-00171. [PMID: 39150439 DOI: 10.1097/mco.0000000000001065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
PURPOSE OF REVIEW This review aims to explore the latest research investigating the effects of marine-derived long-chain n-3 polyunsaturated fatty acid (LCn-3 PUFA) supplementation on neuromuscular function in older adults. RECENT FINDINGS Ageing results in a decline in skeletal muscle strength and mass. There is growing evidence that LCn-3 PUFA supplementation increases muscle strength and mass in healthy older adults, yet the mechanisms underlying these effects remain elusive. Recent studies investigating LCn-3 PUFA supplementation have demonstrated effects on neuromuscular function such as increases in the compound muscle action potential (M-wave) amplitude and surface electromyography alongside increases in muscular strength. Therefore, evidence suggests that LCn-3 PUFA may elicit a beneficial effect at the neuromuscular junction and possess neuroprotective properties in older adults. SUMMARY LCn-3 PUFA supplementation may increase or maintain neuromuscular function throughout the ageing process. Further research is warranted to investigate the long-term effects LCn-3 PUFA supplementation on neuromuscular outcomes such as single motor unit properties and cortical/supraspinal networks, utilizing state-of-the-art techniques in neuromuscular physiology.
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Affiliation(s)
- Oliver Hayman
- School of Cardiovascular and Metabolic Health, BHF Glasgow Cardiovascular, Research Centre, College of Medical, Veterinary and Life Sciences
| | - Emilie Combet
- School of Medicine, Dentistry and Nursing, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland
| | - Oliver C Witard
- Centre for Human and Applied Physiological Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Stuart R Gray
- School of Cardiovascular and Metabolic Health, BHF Glasgow Cardiovascular, Research Centre, College of Medical, Veterinary and Life Sciences
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Pabla P, Jones E, Piasecki M, Phillips B. Skeletal muscle dysfunction with advancing age. Clin Sci (Lond) 2024; 138:863-882. [PMID: 38994723 PMCID: PMC11250095 DOI: 10.1042/cs20231197] [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: 03/14/2024] [Revised: 06/15/2024] [Accepted: 06/20/2024] [Indexed: 07/13/2024]
Abstract
As a result of advances in medical treatments and associated policy over the last century, life expectancy has risen substantially and continues to increase globally. However, the disconnect between lifespan and 'health span' (the length of time spent in a healthy, disease-free state) has also increased, with skeletal muscle being a substantial contributor to this. Biological ageing is accompanied by declines in both skeletal muscle mass and function, termed sarcopenia. The mechanisms underpinning sarcopenia are multifactorial and are known to include marked alterations in muscle protein turnover and adaptations to the neural input to muscle. However, to date, the relative contribution of each factor remains largely unexplored. Specifically, muscle protein synthetic responses to key anabolic stimuli are blunted with advancing age, whilst alterations to neural components, spanning from the motor cortex and motoneuron excitability to the neuromuscular junction, may explain the greater magnitude of function losses when compared with mass. The consequences of these losses can be devastating for individuals, their support networks, and healthcare services; with clear detrimental impacts on both clinical (e.g., mortality, frailty, and post-treatment complications) and societal (e.g., independence maintenance) outcomes. Whether declines in muscle quantity and quality are an inevitable component of ageing remains to be completely understood. Nevertheless, strategies to mitigate these declines are of vital importance to improve the health span of older adults. This review aims to provide an overview of the declines in skeletal muscle mass and function with advancing age, describes the wide-ranging implications of these declines, and finally suggests strategies to mitigate them, including the merits of emerging pharmaceutical agents.
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Affiliation(s)
- Pardeep Pabla
- Centre of Metabolism, Ageing and Physiology (COMAP), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, DE22 3DT, U.K
| | - Eleanor J. Jones
- Centre of Metabolism, Ageing and Physiology (COMAP), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, DE22 3DT, U.K
| | - Mathew Piasecki
- Centre of Metabolism, Ageing and Physiology (COMAP), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, DE22 3DT, U.K
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research (CMAR), U.K
- NIHR Nottingham Biomedical Research Centre (BRC), U.K
| | - Bethan E. Phillips
- Centre of Metabolism, Ageing and Physiology (COMAP), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, DE22 3DT, U.K
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research (CMAR), U.K
- NIHR Nottingham Biomedical Research Centre (BRC), U.K
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Birkbeck MG, Heskamp L, Schofield IS, Hall J, Sayer AA, Whittaker RG, Blamire AM. Whole Muscle and Single Motor Unit Twitch Profiles in a Healthy Adult Cohort Assessed With Phase Contrast Motor Unit MRI (PC-MUMRI). J Magn Reson Imaging 2024; 60:205-217. [PMID: 37776094 DOI: 10.1002/jmri.29028] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/13/2023] [Accepted: 09/13/2023] [Indexed: 10/01/2023] Open
Abstract
BACKGROUND Motor units (MUs) control the contraction of muscles and degenerate with age. It is therefore of interest to measure whole muscle and MU twitch profiles in aging skeletal muscle. PURPOSE Apply phase contrast MU MRI (PC-MUMRI) in a cohort of healthy adults to measure whole anterior compartment, individual muscles, and single MU twitch profiles in the calf. Assess the effect of age and sex on contraction and relaxation times. STUDY TYPE Prospective cross-sectional study. SUBJECTS Sixty-one healthy participants (N = 32 male; age 55 ± 16 years [range: 26-82]). FIELD STRENGTH/SEQUENCES 3 T, velocity encoded gradient echo and single shot spin echo pulsed gradient spin echo, echo-planar imaging. ASSESSMENT Anterior shin compartment (N = 47), individual muscle (tibialis anterior, extensor digitorum longus, peroneus longus; N = 47) and single MU (N = 34) twitch profiles were extracted from the data to calculate contraction and relaxation times. STATISTICAL TESTS Multivariable linear regression to investigate relationships between age, sex and contraction and relaxation times of the whole anterior compartment. Pearson correlation to investigate relationships between age and contraction and relaxation times of individual muscles and single MUs. A P value <0.05 was considered statistically significant. RESULTS Age and sex predicted significantly increased contraction and relaxation time for the anterior compartment. Females had significantly longer contraction times than males (females 86 ± 8 msec, males 80 ± 9 msec). Relaxation times were longer, not significant (females 204 ± 36 msec, males 188 ± 34 msec, P = 0.151). Contraction and relaxation times of single MUs showed no change with age (P = 0.462, P = 0.534, respectively). DATE CONCLUSION Older participants had significantly longer contraction and relaxation times of the whole anterior compartment compared to younger participants. Females had longer contraction and relaxation times than males, significant for contraction time. EVIDENCE LEVEL 2 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Matthew G Birkbeck
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, Newcastle upon Tyne, UK
- Northern Medical Physics and Clinical Engineering, Freeman Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Linda Heskamp
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Ian S Schofield
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Julie Hall
- Department of Neuroradiology, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle University, Newcastle upon Tyne, UK
| | - Avan A Sayer
- NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, Newcastle upon Tyne, UK
| | - Roger G Whittaker
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Andrew M Blamire
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
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Johnson D, Tobo C, Au J, Nagarapu A, Ziemkiewicz N, Chauvin H, Robinson J, Shringarpure S, Tadiwala J, Brockhouse J, Flaveny CA, Garg K. Combined regenerative rehabilitation improves recovery following volumetric muscle loss injury in a rat model. J Biomed Mater Res B Appl Biomater 2024; 112:e35438. [PMID: 38923755 PMCID: PMC11210688 DOI: 10.1002/jbm.b.35438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 02/27/2024] [Accepted: 06/03/2024] [Indexed: 06/28/2024]
Abstract
Volumetric muscle loss (VML) injury causes irreversible deficits in muscle mass and function, often resulting in permanent disability. The current standard of care is physical therapy, but it is limited in mitigating functional deficits. We have previously optimized a rehabilitation technique using electrically stimulated eccentric contraction training (EST) that improved muscle mass, strength, and size in VML-injured rats. A biosponge scaffold composed of extracellular matrix proteins has previously enhanced muscle function postVML. This study aimed to determine whether combining a regenerative therapy (i.e., biosponge) with a novel rehabilitation technique (i.e., EST) could enhance recovery in a rat model of VML. A VML defect was created by removing ~20% of muscle mass from the tibialis anterior muscle in adult male Lewis rats. Experimental groups included VML-injured rats treated with biosponge with EST or biosponge alone (n = 6/group). EST was implemented 2 weeks postinjury at 150 Hz and was continued for 4 weeks. A linear increase in eccentric torque over 4 weeks showed the adaptability of the VML-injured muscle to EST. Combining biosponge with EST improved peak isometric torque by ~52% compared with biosponge treatment alone at 6 weeks postinjury. Application of EST increased MyoD gene expression and the percentage of large (>2000 μm2) type 2B myofibers but reduced fibrotic tissue deposition in VML-injured muscles. Together, these changes may provide the basis for improved torque production. This study demonstrates the potential for combined regenerative and rehabilitative therapy to improve muscle recovery following VML.
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Affiliation(s)
- David Johnson
- Department of Biomedical Engineering, School of Sciences and Engineering
| | - Connor Tobo
- Department of Biomedical Engineering, School of Sciences and Engineering
| | - Jeffrey Au
- Department of Biomedical Engineering, School of Sciences and Engineering
| | - Aakash Nagarapu
- Department of Biomedical Engineering, School of Sciences and Engineering
| | | | - Hannah Chauvin
- Department of Biomedical Engineering, School of Sciences and Engineering
| | - Jessica Robinson
- Department of Biomedical Engineering, School of Sciences and Engineering
| | | | - Jamshid Tadiwala
- Department of Biomedical Engineering, School of Sciences and Engineering
| | - Julia Brockhouse
- Department of Biomedical Engineering, School of Sciences and Engineering
| | | | - Koyal Garg
- Department of Biomedical Engineering, School of Sciences and Engineering
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Deane C, Piasecki M, Atherton P. Skeletal muscle immobilisation-induced atrophy: mechanistic insights from human studies. Clin Sci (Lond) 2024; 138:741-756. [PMID: 38895777 PMCID: PMC11186857 DOI: 10.1042/cs20231198] [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: 02/16/2024] [Revised: 05/28/2024] [Accepted: 06/04/2024] [Indexed: 06/21/2024]
Abstract
Periods of skeletal muscle disuse lead to rapid declines in muscle mass (atrophy), which is fundamentally underpinned by an imbalance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). The complex interplay of molecular mechanisms contributing to the altered regulation of muscle protein balance during disuse have been investigated but rarely synthesised in the context of humans. This narrative review discusses human models of muscle disuse and the ensuing inversely exponential rate of muscle atrophy. The molecular processes contributing to altered protein balance are explored, with a particular focus on growth and breakdown signalling pathways, mitochondrial adaptations and neuromuscular dysfunction. Finally, key research gaps within the disuse atrophy literature are highlighted providing future avenues to enhance our mechanistic understanding of human disuse atrophy.
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Affiliation(s)
- Colleen S. Deane
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton General Hospital, U.K
| | - Matthew Piasecki
- Centre of Metabolism, Ageing and Physiology (CoMAP), Medical Research Council/Versus Arthritis UK Centre of Excellence for Musculoskeletal Ageing Research (CMAR), National Institute of Health Research (NIHR) Biomedical Research Centre (BRC), University of Nottingham, U.K
| | - Philip J. Atherton
- Centre of Metabolism, Ageing and Physiology (CoMAP), Medical Research Council/Versus Arthritis UK Centre of Excellence for Musculoskeletal Ageing Research (CMAR), National Institute of Health Research (NIHR) Biomedical Research Centre (BRC), University of Nottingham, U.K
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Guo Y, Jones EJ, Smart TF, Altheyab A, Gamage N, Stashuk DW, Piasecki J, Phillips BE, Atherton PJ, Piasecki M. Sex disparities of human neuromuscular decline in older humans. J Physiol 2024. [PMID: 38857412 DOI: 10.1113/jp285653] [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: 09/08/2023] [Accepted: 05/07/2024] [Indexed: 06/12/2024] Open
Abstract
Females typically live longer than males but, paradoxically, spend a greater number of later years in poorer health. The neuromuscular system is a critical component of the progression to frailty, and motor unit (MU) characteristics differ by sex in healthy young individuals and may adapt to ageing in a sex-specific manner due to divergent hormonal profiles. The purpose of this study was to investigate sex differences in vastus lateralis (VL) MU structure and function in early to late elderly humans. Intramuscular electromyography signals from 50 healthy older adults (M/F: 26/24) were collected from VL during standardized submaximal contractions and decomposed to quantify MU characteristics. Muscle size and neuromuscular performance were also measured. Females had higher MU firing rate (FR) than males (P = 0.025), with no difference in MU structure or neuromuscular junction transmission (NMJ) instability. All MU characteristics increased from low- to mid-level contractions (P < 0.05) without sex × level interactions. Females had smaller cross-sectional area of VL, lower strength and poorer force steadiness (P < 0.05). From early to late elderly, both sexes showed decreased neuromuscular function (P < 0.05) without sex-specific patterns. Higher VL MUFRs at normalized contraction levels previously observed in young are also apparent in old individuals, with no sex-based difference of estimates of MU structure or NMJ transmission instability. From early to late elderly, the deterioration of neuromuscular function and MU characteristics did not differ between sexes, yet function was consistently greater in males. These parallel trajectories underscore the lower initial level for older females and may offer insights into identifying critical intervention periods. KEY POINTS: Females generally exhibit an extended lifespan when compared to males, yet this is accompanied by a poorer healthspan and higher rates of frailty. In healthy young people, motor unit firing rate (MUFR) at normalized contraction intensities is widely reported to be higher in females than in age-matched males. Here we show in 50 people that older females have higher MUFR than older males with little difference in other MU parameters. The trajectory of decline from early to late elderly does not differ between sexes, yet function is consistently lower in females. These findings highlight distinguishable sex disparities in some MU characteristics and neuromuscular function, and suggest early interventions are needed for females to prevent functional deterioration to reduce the ageing health-sex paradox.
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Affiliation(s)
- Yuxiao Guo
- Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, China
- 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, Nottingham, 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, Nottingham, UK
| | - Thomas F Smart
- 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, Nottingham, UK
| | - Abdulmajeed Altheyab
- 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, Nottingham, UK
- College of Applied Medical Sciences, King Saud bin Abdulaziz University for Health Science, Riyadh, Saudi Arabia
| | - Nishadi Gamage
- 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, Nottingham, UK
- Neurophysiology of Human Movement Group, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia
| | - Daniel W Stashuk
- Department of Systems Design Engineering, University of Waterloo, Waterloo, Ontario, Canada
| | - 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, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Nottingham, 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, Nottingham, 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, Nottingham, UK
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Kunugi S, Holobar A, Nakagoshi A, Kawabe K, Watanabe K. Effects of repetition of a car-driving pedal maneuver and neural output in older adults. J Electromyogr Kinesiol 2024; 76:102883. [PMID: 38569438 DOI: 10.1016/j.jelekin.2024.102883] [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: 09/18/2023] [Revised: 03/11/2024] [Accepted: 03/30/2024] [Indexed: 04/05/2024] Open
Abstract
Understanding the ability of older adults to control pedal position angle and investigating whether this ability can be enhanced through practice may contribute to the prevention of traffic accidents. This study aimed to investigate repetitive effects on variability of the pedal position and neural drive during car-pedal operation in older adults. Thirteen older and 11 young adults performed 105 (21 sets × 5 repetitions) pedal angle control tasks with plantar flexor contraction. High-density surface electromyograms were recorded of triceps surae muscles. A cumulative spike train as a neural drive was calculated using continuously active motor unit activities. The coefficient of variation of the angle was higher in older (1.47 ± 1.06 %) than young (0.41 ± 0.21 %) adults in the first sets, and improved to 0.67 ± 0.51 % in the final sets in older adults only. There was no significant difference in neural drive variability between older and young adults. Our results suggest that repetition improves angular steadiness in older adults. However, this effect could not be explained by neural output which is estimated from lower threshold motor units that are continuously active.
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Affiliation(s)
- Shun Kunugi
- Center for General Education, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota-shi, Aichi 470-0392, Japan; Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University 101 Tokodachi, Kaizu-cho, Toyota-shi, Aichi 470-0393, Japan.
| | - Aleš Holobar
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Koroška cesta 46, 2000 Maribor, Slovenia
| | - Akira Nakagoshi
- Advanced Mobility System Development, Toyota Motor Corporation, 1 Toyota-cho, Toyota-shi, Aichi 471-8571, Japan
| | - Kyosuke Kawabe
- Advanced Mobility System Development, Toyota Motor Corporation, 1 Toyota-cho, Toyota-shi, Aichi 471-8571, Japan
| | - Kohei Watanabe
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University 101 Tokodachi, Kaizu-cho, Toyota-shi, Aichi 470-0393, Japan
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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: 3] [Impact Index Per Article: 3.0] [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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Ruple BA, Mattingly ML, Godwin JS, McIntosh MC, Kontos NJ, Agyin-Birikorang A, Michel JM, Plotkin DL, Chen SY, Ziegenfuss TN, Fruge AD, Gladden LB, Robinson AT, Mobley CB, Mackey AL, Roberts MD. The effects of resistance training on denervated myofibers, senescent cells, and associated protein markers in middle-aged adults. FASEB J 2024; 38:e23621. [PMID: 38651653 PMCID: PMC11047210 DOI: 10.1096/fj.202302103rrr] [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: 10/16/2023] [Revised: 04/04/2024] [Accepted: 04/08/2024] [Indexed: 04/25/2024]
Abstract
Denervated myofibers and senescent cells are hallmarks of skeletal muscle aging. However, sparse research has examined how resistance training affects these outcomes. We investigated the effects of unilateral leg extensor resistance training (2 days/week for 8 weeks) on denervated myofibers, senescent cells, and associated protein markers in apparently healthy middle-aged participants (MA, 55 ± 8 years old, 17 females, 9 males). We obtained dual-leg vastus lateralis (VL) muscle cross-sectional area (mCSA), VL biopsies, and strength assessments before and after training. Fiber cross-sectional area (fCSA), satellite cells (Pax7+), denervated myofibers (NCAM+), senescent cells (p16+ or p21+), proteins associated with denervation and senescence, and senescence-associated secretory phenotype (SASP) proteins were analyzed from biopsy specimens. Leg extensor peak torque increased after training (p < .001), while VL mCSA trended upward (interaction p = .082). No significant changes were observed for Type I/II fCSAs, NCAM+ myofibers, or senescent (p16+ or p21+) cells, albeit satellite cells increased after training (p = .037). While >90% satellite cells were not p16+ or p21+, most p16+ and p21+ cells were Pax7+ (>90% on average). Training altered 13 out of 46 proteins related to muscle-nerve communication (all upregulated, p < .05) and 10 out of 19 proteins related to cellular senescence (9 upregulated, p < .05). Only 1 out of 17 SASP protein increased with training (IGFBP-3, p = .031). In conclusion, resistance training upregulates proteins associated with muscle-nerve communication in MA participants but does not alter NCAM+ myofibers. Moreover, while training increased senescence-related proteins, this coincided with an increase in satellite cells but not alterations in senescent cell content or SASP proteins. These latter findings suggest shorter term resistance training is an unlikely inducer of cellular senescence in apparently healthy middle-aged participants. However, similar study designs are needed in older and diseased populations before definitive conclusions can be drawn.
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Affiliation(s)
| | | | | | | | | | | | - J. Max Michel
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | | | | | | | | | | | | | | | - Abigail L. Mackey
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, DK
- Institute of Sports Medicine Copenhagen, Department of Orthopaedic Surgery, Copenhagen University Hospital – Bispebjerg and Frederiksberg, Copenhagen, Denmark
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10
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Piasecki J, Škarabot J, Spillane P, Piasecki M, Ansdell P. Sex Differences in Neuromuscular Aging: The Role of Sex Hormones. Exerc Sport Sci Rev 2024; 52:54-62. [PMID: 38329342 DOI: 10.1249/jes.0000000000000335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Males and females experience different trajectories of neuromuscular function across the lifespan, with females demonstrating accelerated deconditioning in later life. We hypothesize that the menopause is a critical period in the female lifespan, during which the dramatic reduction in sex hormone concentrations negatively impacts synaptic input to the motoneuron pool, as well as motor unit discharge properties.
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Affiliation(s)
- Jessica Piasecki
- Sport, Health and Performance Enhancement Research Centre, Nottingham Trent University, Nottingham, UK
| | - Jakob Škarabot
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Padraig Spillane
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - 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, University of Nottingham, Nottingham, UK
| | - Paul Ansdell
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
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Hirono T, Takeda R, Nishikawa T, Okudaira M, Kunugi S, Yoshiko A, Ueda S, Yoshimura A, Watanabe K. Motor unit firing patterns in older adults with low skeletal muscle mass. Arch Gerontol Geriatr 2024; 116:105151. [PMID: 37544147 DOI: 10.1016/j.archger.2023.105151] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 07/17/2023] [Accepted: 07/31/2023] [Indexed: 08/08/2023]
Abstract
Muscular dysfunctions involving a decline in muscle strength are often induced by loss of muscle mass in older adults. Understanding neural activation in older adults in addition to muscular characteristics may be important to prevent such age-related dysfunctions. This study aimed to investigate the difference in motor unit firing patterns between community-dwelling older individuals with normal and low skeletal muscle mass. Sixty-six older adults (62-90 years) performed muscle strength and function tests. On conducting high-density surface electromyography of the vastus lateralis, individual motor unit firing properties were assessed. Individual motor units were divided into three different recruitment threshold groups and their firing rates were compared. The skeletal muscle quantity and quality were assessed using bioimpedance methods and ultrasound images. They were divided into two groups according to sarcopenia criteria: a normal group (n = 39) and presarcopenia group with low skeletal muscle mass but normal physical functions (n = 21). Skeletal muscle mass and muscle thickness were greater and echo intensity was lower in the normal group than presarcopenia group. Motor units in normal older adults fired at different rates with a hierarchy depending on their recruitment threshold, observed as a normal phenomenon. However, motor units in the presarcopenia group fired without showing the hierarchical pattern. The results suggest that older adults with low skeletal muscle mass exhibited an abnormal neural input pattern, in addition to declines in muscle quantity and quality.
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Affiliation(s)
- Tetsuya Hirono
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Aichi, Japan; Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
| | - Ryosuke Takeda
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Aichi, Japan
| | - Taichi Nishikawa
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Aichi, Japan
| | - Masamichi Okudaira
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Aichi, Japan; Faculty of Education, Iwate University, Iwate, Japan
| | - Shun Kunugi
- Center for General Education, Aichi Institute of Technology, Aichi, Japan
| | - Akito Yoshiko
- Faculty of Liberal Arts and Sciences, Chukyo University, Aichi, Japan
| | - Saeko Ueda
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Aichi, Japan; Department of Human Nutrition, School of Life Studies, Sugiyama Jogakuen University, Aichi, Japan
| | - Akane Yoshimura
- Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, Japan
| | - Kohei Watanabe
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Aichi, Japan
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12
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Ziemkiewicz N, Au J, Chauvin HM, Garg K. Electrically stimulated eccentric contraction training enhances muscle mass, function, and size following volumetric muscle loss. J Orthop Res 2023; 41:2588-2598. [PMID: 37132367 DOI: 10.1002/jor.25591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 03/14/2023] [Accepted: 05/01/2023] [Indexed: 05/04/2023]
Abstract
Volumetric muscle loss (VML) overwhelms muscle's innate capacity for repair and can lead to permanent disability. The standard of care for VML injuries includes physical therapy, which can improve muscle function. The objective of this study was to develop and evaluate a rehabilitative therapy using electrically stimulated eccentric contraction training (EST) and determine the structural, biomolecular, and functional response of the VML-injured muscle. This study implemented EST using three different frequencies (50, 100, and 150 Hz) in VML-injured rats starting at 2 weeks postinjury. Four weeks of EST at 150 Hz showed a progressive increase in eccentric torque with an improvement in muscle mass (~39%), myofiber cross-sectional area, and peak isometric torque (~37.5%) relative to the untrained VML-injured sham group. EST at 150 Hz group also increased the number of large type 2B fibers (>5000 µm2 ). Elevated gene expression of markers associated with angiogenesis, myogenesis, neurogenesis, and an anti-inflammatory response was also observed. These results suggest that VML-injured muscles can respond and adapt to eccentric loading. The results of this study may aid in developing physical therapy regimens for traumatized muscles.
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Affiliation(s)
- Natalia Ziemkiewicz
- Department of Biomedical Engineering, Parks College of Engineering, Aviation and Technology, Saint Louis University, St. Louis, Missouri, USA
| | - Jeffrey Au
- Department of Biomedical Engineering, Parks College of Engineering, Aviation and Technology, Saint Louis University, St. Louis, Missouri, USA
| | - Hannah M Chauvin
- Department of Biomedical Engineering, Parks College of Engineering, Aviation and Technology, Saint Louis University, St. Louis, Missouri, USA
| | - Koyal Garg
- Department of Biomedical Engineering, Parks College of Engineering, Aviation and Technology, Saint Louis University, St. Louis, Missouri, USA
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13
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Hastings RL, Avila MF, Suneby E, Juros D, O'Young A, Peres da Silva J, Valdez G. Cellular and molecular evidence that synaptic Schwann cells contribute to aging of mouse neuromuscular junctions. Aging Cell 2023; 22:e13981. [PMID: 37771191 PMCID: PMC10652323 DOI: 10.1111/acel.13981] [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: 04/28/2023] [Revised: 08/17/2023] [Accepted: 08/18/2023] [Indexed: 09/30/2023] Open
Abstract
Age-induced degeneration of the neuromuscular junction (NMJ) is associated with motor dysfunction and muscle atrophy. While the impact of aging on the NMJ presynapse and postsynapse is well-documented, little is known about the changes perisynaptic Schwann cells (PSCs), the synaptic glia of the NMJ, undergo during aging. Here, we examined PSCs in young, middle-aged, and old mice in three muscles with different susceptibility to aging. Using light and electron microscopy, we found that PSCs acquire age-associated cellular features either prior to or at the same time as the onset of NMJ degeneration. Notably, we found that aged PSCs fail to completely cap the NMJ even though they are more abundant in old compared with young mice. We also found that aging PSCs form processes that either intrude into the synaptic cleft or guide axonal sprouts to innervate other NMJs. We next profiled the transcriptome of PSCs and other Schwann cells (SCs) to identify mechanisms altered in aged PSCs. This analysis revealed that aged PSCs acquire a transcriptional pattern previously shown to promote phagocytosis that is absent in other SCs. It also showed that aged PSCs upregulate unique pro-inflammatory molecules compared to other aged SCs. Interestingly, neither synaptogenesis genes nor genes that are typically upregulated by repair SCs were induced in aged PSCs or other SCs. These findings provide insights into cellular and molecular mechanisms that could be targeted in PSCs to stave off the deleterious effects of aging on NMJs.
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Affiliation(s)
- Robert Louis Hastings
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | | | - Emma Suneby
- Molecular Biology, Cell Biology, & Biochemistry Graduate Program, Brown University, Providence, Rhode Island, USA
| | - Devin Juros
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Anson O'Young
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Jason Peres da Silva
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Gregorio Valdez
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
- Center for Translational Neuroscience, Robert J. and Nancy D. Carney Institute for Brain Science, and Center on the Biology of Aging, Brown University, Providence, Rhode Island, USA
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14
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Gogeascoechea A, Ornelas-Kobayashi R, Yavuz US, Sartori M. Characterization of Motor Unit Firing and Twitch Properties for Decoding Musculoskeletal Force in the Human Ankle Joint In Vivo. IEEE Trans Neural Syst Rehabil Eng 2023; 31:4040-4050. [PMID: 37756177 DOI: 10.1109/tnsre.2023.3319959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
Understanding how motor units (MUs) contribute to skeletal mechanical force is crucial for unraveling the underlying mechanism of human movement. Alterations in MU firing, contractile and force-generating properties emerge in response to physical training, aging or injury. However, how changes in MU firing and twitch properties dictate skeletal muscle force generation in healthy and impaired individuals remains an open question. In this work, we present a MU-specific approach to identify firing and twitch properties of MU samples and employ them to decode musculoskeletal function in vivo. First, MU firing events were decomposed offline from high-density electromyography (HD-EMG) of six lower leg muscles involved in ankle plantar-dorsi flexion. We characterized their twitch responses based on the statistical distributions of their firing properties and employed them to compute MU-specific activation dynamics. Subsequently, we decoded ankle joint moments by linking our framework to a subject-specific musculoskeletal model. We validated our approach at different ankle positions and levels of activation and compared it with traditional EMG-driven models. Our proposed MU-specific formulation achieves higher generalization across conditions than the EMG-driven models, with significantly lower coefficients of variation in torque predictions. Furthermore, our approach shows distinct neural strategies across a large repertoire of contractile conditions in different muscles. Our proposed approach may open new avenues for characterizing the relationship between MU firing and twitch properties and their influence on force capacity. This can facilitate the development of targeted rehabilitation strategies tailored to individuals with specific neuromuscular conditions.
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15
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Clark BC. Neural Mechanisms of Age-Related Loss of Muscle Performance and Physical Function. J Gerontol A Biol Sci Med Sci 2023; 78:8-13. [PMID: 36738253 PMCID: PMC10272985 DOI: 10.1093/gerona/glad029] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND This article discusses the putative neural mechanisms of age-related muscle weakness within the broader context of the development of function-promoting therapies for sarcopenia and age-related mobility limitations. We discuss here the evolving definition of sarcopenia and its primary defining characteristic, weakness. METHODS This review explores the premise that impairments in the nervous system's ability to generate maximal force or power contribute to sarcopenia. RESULTS Impairments in neural activation are responsible for a substantial amount of age-related weakness. The neurophysiological mechanisms of weakness are multifactorial. The roles of supraspinal descending command mechanisms, spinal motor neuron firing responsivity, and neuromuscular junction transmission failure in sarcopenia are discussed. Research/clinical gaps and recommendations for future work are highlighted. CONCLUSION Further research is needed to map putative neural mechanisms, determine the clinical relevance of age-related changes in neural activation to sarcopenia, and evaluate the effectiveness of various neurotherapeutic approaches to enhancing physical function.
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Affiliation(s)
- Brian C Clark
- Ohio Musculoskeletal and Neurological Institute (OMNI) and the Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
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16
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Jones EJ, Guo Y, Martinez‐Valdes E, Negro F, Stashuk DW, Atherton PJ, Phillips BE, Piasecki M. Acute adaptation of central and peripheral motor unit features to exercise-induced fatigue differs with concentric and eccentric loading. Exp Physiol 2023; 108:827-837. [PMID: 37018481 PMCID: PMC10988466 DOI: 10.1113/ep091058] [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: 12/01/2022] [Accepted: 03/14/2023] [Indexed: 04/07/2023]
Abstract
NEW FINDINGS What is the central question of this study? Conflicting evidence exists on motor unit (MU) firing rate in response to exercise-induced fatigue, possibly due to the contraction modality used: Do MU properties adapt similarly following concentric and eccentric loading? What is the main finding and its importance? MU firing rate increased following eccentric loading only despite a decline in absolute force. Force steadiness deteriorated following both loading methods. Central and peripheral MU features are altered in a contraction type-dependant manner, which is an important consideration for training interventions. ABSTRACT Force output of muscle is partly mediated by the adjustment of motor unit (MU) firing rate (FR). Disparities in MU features in response to fatigue may be influenced by contraction type, as concentric (CON) and eccentric (ECC) contractions demand variable amounts of neural input, which alters the response to fatigue. This study aimed to determine the effects of fatigue following CON and ECC loading on MU features of the vastus lateralis (VL). High-density surface (HD-sEMG) and intramuscular (iEMG) electromyography were used to record MU potentials (MUPs) from bilateral VLs of 12 young volunteers (six females) during sustained isometric contractions at 25% and 40% of the maximum voluntary contraction (MVC), before and after completing CON and ECC weighted stepping exercise. Multi-level mixed effects linear regression models were performed with significance assumed as P < 0.05. MVC decreased in both CON and ECC legs post-exercise (P < 0.0001), as did force steadiness at both 25% and 40% MVC (P < 0.004). MU FR increased in ECC at both contraction levels (P < 0.001) but did not change in CON. FR variability increased in both legs at 25% and 40% MVC following fatigue (P < 0.01). From iEMG measures at 25% MVC, MUP shape did not change (P > 0.1) but neuromuscular junction transmission instability increased in both legs (P < 0.04), and markers of fibre membrane excitability increased following CON only (P = 0.018). These data demonstrate that central and peripheral MU features are altered following exercise-induced fatigue and differ according to exercise modality. This is important when considering interventional strategies targeting MU function.
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Affiliation(s)
- Eleanor J. Jones
- Centre of Metabolism, Ageing and Physiology (COMAP), MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research CentreUniversity of NottinghamNottinghamUK
| | - Yuxiao Guo
- Centre of Metabolism, Ageing and Physiology (COMAP), MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research CentreUniversity of NottinghamNottinghamUK
| | - Eduardo Martinez‐Valdes
- Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental SciencesUniversity of BirminghamBirminghamUK
| | - Francesco Negro
- Department of Clinical and Experimental SciencesUniversità degli Studi di BresciaBresciaItaly
| | - Daniel W. Stashuk
- Department of Systems Design EngineeringUniversity of WaterlooWaterlooOntarioCanada
| | - Philip J. Atherton
- Centre of Metabolism, Ageing and Physiology (COMAP), MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research CentreUniversity of NottinghamNottinghamUK
| | - Bethan E. Phillips
- Centre of Metabolism, Ageing and Physiology (COMAP), MRC‐Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research CentreUniversity of NottinghamNottinghamUK
| | - 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 CentreUniversity of NottinghamNottinghamUK
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17
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Lu Y, Bu FQ, Wang F, Liu L, Zhang S, Wang G, Hu XY. Recent advances on the molecular mechanisms of exercise-induced improvements of cognitive dysfunction. Transl Neurodegener 2023; 12:9. [PMID: 36850004 PMCID: PMC9972637 DOI: 10.1186/s40035-023-00341-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 02/09/2023] [Indexed: 03/01/2023] Open
Abstract
Physical exercise is of great significance for maintaining human health. Exercise can provide varying degrees of benefits to cognitive function at all stages of life cycle. Currently, with the aging of the world's population and increase of life expectancy, cognitive dysfunction has gradually become a disease of high incidence, which is accompanied by neurodegenerative diseases in elderly individuals. Patients often exhibit memory loss, aphasia and weakening of orientation once diagnosed, and are unable to have a normal life. Cognitive dysfunction largely affects the physical and mental health, reduces the quality of life, and causes a great economic burden to the society. At present, most of the interventions are aimed to maintain the current cognitive level and delay deterioration of cognition. In contrast, exercise as a nonpharmacological therapy has great advantages in its nontoxicity, low cost and universal application. The molecular mechanisms underlying the effect of exercise on cognition are complex, and studies have been extensively centered on neural plasticity, the direct target of exercise in the brain. In addition, mitochondrial stability and energy metabolism are essential for brain status. Meanwhile, the organ-brain axis responds to exercise and induces release of cytokines related to cognition. In this review, we summarize the latest evidence on the molecular mechanisms underlying the effects of exercise on cognition, and point out directions for future research.
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Affiliation(s)
- Yi Lu
- grid.13291.380000 0001 0807 1581West China School of Nursing, Sichuan University/Innovation Center of Nursing Research, Nursing Key Laboratory of Sichuan Province, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041 China
| | - Fa-Qian Bu
- grid.13291.380000 0001 0807 1581West China School of Nursing, Sichuan University/Innovation Center of Nursing Research, Nursing Key Laboratory of Sichuan Province, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041 China
| | - Fang Wang
- grid.13291.380000 0001 0807 1581West China School of Nursing, Sichuan University/Innovation Center of Nursing Research, Nursing Key Laboratory of Sichuan Province, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041 China
| | - Li Liu
- grid.13291.380000 0001 0807 1581West China School of Nursing, Sichuan University/Innovation Center of Nursing Research, Nursing Key Laboratory of Sichuan Province, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041 China
| | - Shuai Zhang
- grid.13291.380000 0001 0807 1581West China School of Nursing, Sichuan University/Innovation Center of Nursing Research, Nursing Key Laboratory of Sichuan Province, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041 China
| | - Guan Wang
- West China School of Nursing, Sichuan University/Innovation Center of Nursing Research, Nursing Key Laboratory of Sichuan Province, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, China.
| | - Xiu-Ying Hu
- West China School of Nursing, Sichuan University/Innovation Center of Nursing Research, Nursing Key Laboratory of Sichuan Province, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, China.
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18
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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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19
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Kambič T, Farkaš J, Lainscak M. Comment on: "Effects of resistance training intensity on muscle quantity/quality in middle-aged and older people: a randomized controlled trial" by Otsuka et al. J Cachexia Sarcopenia Muscle 2022; 13:2579-2580. [PMID: 35860902 PMCID: PMC9530533 DOI: 10.1002/jcsm.13036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Tim Kambič
- Cardiac Rehabilitation Unit, and Department of Research and Education, General Hospital Murska Sobota, Murska Sobota, Slovenia
| | - Jerneja Farkaš
- Cardiac Rehabilitation Unit, and Department of Research and Education, General Hospital Murska Sobota, Murska Sobota, Slovenia.,National Institute of Public Health, Ljubljana, Slovenia.,Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Mitja Lainscak
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Division of Cardiology, General Hospital Murska Sobota, Murska Sobota, Slovenia
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20
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Škarabot J, Folland JP, Holobar A, Baker SN, Del Vecchio A. Startling stimuli increase maximal motor unit discharge rate and rate of force development in humans. J Neurophysiol 2022; 128:455-469. [PMID: 35829632 PMCID: PMC9423775 DOI: 10.1152/jn.00115.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Maximal rate of force development in adult humans is determined by the maximal motor unit discharge rate, however the origin of the underlying synaptic inputs remains unclear. Here, we tested a hypothesis that the maximal motor unit discharge rate will increase in response to a startling cue, a stimulus that purportedly activates the pontomedullary reticular formation neurons that make mono- and disynaptic connections to motoneurons via fast-conducting axons. Twenty-two men were required to produce isometric knee extensor forces "as fast and as hard" as possible from rest to 75% of maximal voluntary force, in response to visual (VC), visual-auditory (VAC; 80 dB), or visual-startling cue (VSC; 110 dB). Motoneuron activity was estimated via decomposition of high-density surface electromyogram recordings over the vastus lateralis and medialis muscles. Reaction time was significantly shorter in response to VSC compared to VAC and VC. The VSC further elicited faster neuromechanical responses including a greater number of discharges per motor unit per second and greater maximal rate of force development, with no differences between VAC and VC. We provide evidence, for the first time, that the synaptic input to motoneurons increases in response to a startling cue, suggesting a contribution of subcortical pathways to maximal motoneuron output in humans.
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Affiliation(s)
- Jakob Škarabot
- School of Sport, Exercise and Health Sciences, grid.6571.5Loughborough University, Loughborough, United Kingdom
| | - Jonathan P Folland
- School of Sport, Exercise and Health Sciences, grid.6571.5Loughborough University, Loughborough, United Kingdom.,Versus Arthritis Centre for Sport, Exercise and Osteoarthritis, Loughborough University, Loughborough, United Kingdom
| | - Ales Holobar
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Stuart N Baker
- Medical Faculty, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Alessandro Del Vecchio
- Department of Artificial Intelligence in Biomedical Engineering, University of Erlangen-Nuremberg, Erlangen, Bavaria, Germany
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