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Bertrand MF, Varesco G, Millet GY, Féasson L, Lapole T, Rozand V. Are females getting more fatigable as they age? Eur J Appl Physiol 2024:10.1007/s00421-024-05637-6. [PMID: 39417863 DOI: 10.1007/s00421-024-05637-6] [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: 08/01/2024] [Accepted: 10/04/2024] [Indexed: 10/19/2024]
Abstract
PURPOSE The aim of this study was to compare performance fatigability between young (n = 13; 18-35 yr.; 23.5 ± 3.3 yr.), old (n = 13; 60-79 yr.; 68.2 ± 4.3 yr.), and very old (n = 11; ≥ 80 yr.; 85.6 ± 1.8 yr.) females during single-limb isometric (ISO) vs. isokinetic concentric (CON) vs. cycling (BIKE) fatiguing tasks. METHODS Participants randomly performed three incremental fatiguing tasks where increments were set as percentage of body weight to better reflect the daily life: (1) ISO and (2) CON consisted of stages of 75 contractions (120 s, 0.8 s on/0.8 s off) on an isokinetic dynamometer and (3) BIKE consisted of stages of 120 s at 37.5 rpm with similar duty cycle. Knee extensors maximal force, voluntary activation and potentiated twitch amplitude were measured at baseline, after each stage and at exhaustion. RESULTS Compared to young, exercise performance was 20% and 53% lower in old and very old females in ISO, 46% and 76% lower in CON and 32% and 62% lower in BIKE (all p < 0.01). For a given workload (i.e. common stages), performance fatigability (i.e. force loss) was greater for very old compared to young females in CON only (p = 0.018). At exhaustion, performance fatigability was similar across groups and conditions (~ 30%; all p > 0.05), with similar impairments in both voluntary activation and twitch amplitude. CONCLUSION These results emphasize the importance of the kind of fatiguing task and modalities of evaluation when investigating the effects of aging on performance fatigability.
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Affiliation(s)
- Mathilde Fiona Bertrand
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Jean Monnet Saint-Etienne, Lyon 1, Université Savoie Mont-Blanc, 42023, Saint-Etienne, France
| | - Giorgio Varesco
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
- Center for Advanced Research in Sleep Medicine (CEAMS), Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord de l'Île-de- Montréal, Montreal, QC, Canada
- Institut National du Sport du Québec, Montréal, QC, Canada
| | - Guillaume Y Millet
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Jean Monnet Saint-Etienne, Lyon 1, Université Savoie Mont-Blanc, 42023, Saint-Etienne, France
- IUF, Institut Universitaire de France, Paris, France
| | - Léonard Féasson
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Jean Monnet Saint-Etienne, Lyon 1, Université Savoie Mont-Blanc, 42023, Saint-Etienne, France
- Unité de Myologie, Service de Physiologie Clinique et de l'Exercice, Centre Référent Maladies Neuromusculaires Euro-NmD, CHU de Saint-Etienne, Saint-Etienne, France
| | - Thomas Lapole
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Jean Monnet Saint-Etienne, Lyon 1, Université Savoie Mont-Blanc, 42023, Saint-Etienne, France
- IUF, Institut Universitaire de France, Paris, France
| | - Vianney Rozand
- CAPS, Inserm UMR1093, UFR des Sciences du Sport, Faculté des Sciences du Sport, Université de Bourgogne, BP 27877, 21078, Dijon, France.
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Wrucke DJ, Kuplic A, Adam MD, Hunter SK, Sundberg CW. Neural and muscular contributions to the age-related differences in peak power of the knee extensors in men and women. J Appl Physiol (1985) 2024; 137:1021-1040. [PMID: 39205638 DOI: 10.1152/japplphysiol.00773.2023] [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: 10/31/2023] [Revised: 08/20/2024] [Accepted: 08/20/2024] [Indexed: 09/04/2024] Open
Abstract
The mechanisms for the loss in limb muscle power output in old (60-79 yr) and very old (≥80 yr) adults and whether the mechanisms differ between men and women are not well understood. We compared maximal peak power of the knee extensor muscles between young, old, and very old men and women and identified the neural and muscular factors contributing to the age-related differences in power. Thirty-one young (22.9 ± 3.0 yr, 15 women), 82 old (70.3 ± 4.9 yr, 38 women), and 16 very old adults (85.8 ± 4.2 yr, 9 women) performed maximal isokinetic contractions at 14 different velocities (30-450°/s) to identify peak power. Voluntary activation (VA) and contractile properties were assessed with transcranial magnetic stimulation to the motor cortex and electrical stimulation of the femoral nerve. The age-related loss in peak power was ∼6.5 W·yr-1 for men (R2 = 0.62, P < 0.001), which was a greater rate of decline (P = 0.002) than the ∼4.2 W·yr-1 for women (R2 = 0.77, P < 0.001). Contractile properties were the most closely associated variables with peak power for both sexes, such as the rate of torque development of the potentiated twitch (men: R2 = 0.69, P < 0.001; women: R2 = 0.57, P < 0.001). VA was weakly associated with power in women (R2 = 0.13, P = 0.012) but not in men (P = 0.191). Similarly, neuromuscular activation [rates of electromyography (EMG) rise] during the maximal power contraction was associated with power in women (R2 = 0.07, P = 0.042) but not in men (P = 0.456). These data suggest that the age-related differences in maximal peak power of the knee extensor muscles are due primarily to factors within the muscle for both sexes, although neural factors may play a minor role in older women.NEW & NOTEWORTHY The greater age-related loss in power relative to the loss in muscle mass of the knee extensors was primarily due to factors altering the contractile properties of the muscle for both old and very old (≥80 yr) adults. The mechanisms for the decrements in power with aging appear largely similar for men and women, although neural factors may play more of a role in older women.
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Affiliation(s)
- David J Wrucke
- Exercise and Rehabilitation Sciences Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
| | - Andrew Kuplic
- Exercise and Rehabilitation Sciences Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
| | - Mitchell D Adam
- Exercise and Rehabilitation Sciences Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
| | - Sandra K Hunter
- Exercise and Rehabilitation Sciences Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
- Athletic and Human Performance Research Center, Marquette University, Milwaukee, Wisconsin, United States
| | - Christopher W Sundberg
- Exercise and Rehabilitation Sciences Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
- Athletic and Human Performance Research Center, Marquette University, Milwaukee, Wisconsin, United States
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Heimhofer C, Neumann A, Odermatt I, Bächinger M, Wenderoth N. Finger-specific effects of age on tapping speed and motor fatigability. Front Hum Neurosci 2024; 18:1427336. [PMID: 39386279 PMCID: PMC11461208 DOI: 10.3389/fnhum.2024.1427336] [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: 05/03/2024] [Accepted: 08/22/2024] [Indexed: 10/12/2024] Open
Abstract
Introduction Increased motor fatigability is a symptom of many neuromuscular and neurodegenerative disorders. However, it is difficult to pinpoint pathological motor fatigability, since the phenomena has not yet been fully characterized in the healthy population. In this study, we investigate how motor fatigability differs across age. Given that many disorders involve supraspinal components, we characterize motor fatigability with a paradigm that has previously been associated with supraspinal mechanisms. Finger tapping at maximal speed results in a rapid decrease in movement speed, which is a measure of motor fatigability. Methods We collected finger tapping data in a field experiment from the general population with a smartphone app, and we investigated age differences in maximal tapping speed, as well as the decrease in tapping speed for the index, middle, and little fingers. Results We found that the maximal tapping speed differed significantly between young (18-30 years, n = 194) and aged (50-70 years, n = 176), whereas the fatigability-induced relative decrease in movement speed did not differ between the age groups (average decrease: 17.0% ± 6.9% (young) vs. 16.5% ± 7.5% (aged) decrease). Furthermore, tapping speed and motor fatigability depended on which finger was used. Discussion These findings might relate to dexterity, with more dexterous movements being more resistant to fatigue. In this study, we provide a characterization of motor fatigability in the general population which can be used as a comparison for clinical populations in the future.
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Affiliation(s)
- Caroline Heimhofer
- Neural Control of Movement Lab, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
- Center for Neuroscience Zurich (ZNZ), Federal Institute of Technology Zurich, University and Balgrist Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Amira Neumann
- Neural Control of Movement Lab, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Ingrid Odermatt
- Neural Control of Movement Lab, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
- Center for Neuroscience Zurich (ZNZ), Federal Institute of Technology Zurich, University and Balgrist Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Marc Bächinger
- Neural Control of Movement Lab, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Nicole Wenderoth
- Neural Control of Movement Lab, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
- Center for Neuroscience Zurich (ZNZ), Federal Institute of Technology Zurich, University and Balgrist Hospital Zurich, University of Zurich, Zurich, Switzerland
- Future Health Technologies, Singapore-ETH Centre, Campus for Research Excellence and Technological Enterprise (CREATE), Zurich, Switzerland
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Arieta LR, Smith ZH, Paluch AE, Kent JA. Effects of older age on contraction-induced intramyocellular acidosis and inorganic phosphate accumulation in vivo: A systematic review and meta-analysis. PLoS One 2024; 19:e0308336. [PMID: 39321147 PMCID: PMC11424002 DOI: 10.1371/journal.pone.0308336] [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: 02/26/2024] [Accepted: 07/22/2024] [Indexed: 09/27/2024] Open
Abstract
Although it is clear that the bioenergetic basis of skeletal muscle fatigue (transient decrease in peak torque or power in response to contraction) involves intramyocellular acidosis (decreased pH) and accumulation of inorganic phosphate (Pi) in response to the increased energy demand of contractions, the effects of old age on the build-up of these metabolites has not been evaluated systematically. The purpose of this study was to compare pH and [Pi] in young (18-45 yr) and older (55+ yr) human skeletal muscle in vivo at the end of standardized contraction protocols. Full study details were prospectively registered on PROSPERO (CRD42022348972). PubMed, Web of Science, and SPORTDiscus databases were systematically searched and returned 12 articles that fit the inclusion criteria for the meta-analysis. Participant characteristics, contraction mode (isometric, dynamic), and final pH and [Pi] were extracted. A random-effects model was used to calculate the mean difference (MD) and 95% confidence interval (CI) for pH and [Pi] across age groups. A subgroup analysis for contraction mode was also performed. Young muscle acidified more than older muscle (MD = -0.12 pH; 95%CI = -0.18,-0.06; p<0.01). There was no overall difference by age in final [Pi] (MD = 2.14 mM; 95%CI = -0.29,4.57; p = 0.08), although sensitivity analysis revealed that removing one study resulted in greater [Pi] in young than older muscle (MD = 3.24 mM; 95%CI = 1.72,4.76; p<0.01). Contraction mode moderated these effects (p = 0.02) such that young muscle acidified (MD = -0.19 pH; 95%CI = -0.27,-0.11; p<0.01) and accumulated Pi (MD = 4.69 mM; 95%CI = 2.79,6.59; p<0.01) more than older muscle during isometric, but not dynamic, contractions. The smaller energetic perturbation in older muscle indicated by these analyses is consistent with its relatively greater use of oxidative energy production. During dynamic contractions, elimination of this greater reliance on oxidative energy production and consequently lower metabolite accumulations in older muscle may be important for understanding task-specific, age-related differences in fatigue.
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Affiliation(s)
- Luke R. Arieta
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
| | - Zoe H. Smith
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
| | - Amanda E. Paluch
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
- Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA, United States of America
| | - Jane A. Kent
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
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5
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Hunter SK, Senefeld JW. Sex differences in human performance. J Physiol 2024; 602:4129-4156. [PMID: 39106346 DOI: 10.1113/jp284198] [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: 10/30/2023] [Accepted: 07/08/2024] [Indexed: 08/09/2024] Open
Abstract
Sex as a biological variable is an underappreciated aspect of biomedical research, with its importance emerging in more recent years. This review assesses the current understanding of sex differences in human physical performance. Males outperform females in many physical capacities because they are faster, stronger and more powerful, particularly after male puberty. This review highlights key sex differences in physiological and anatomical systems (generally conferred via sex steroids and puberty) that contribute to these sex differences in human physical performance. Specifically, we address the effects of the primary sex steroids that affect human physical development, discuss insight gained from an observational study of 'real-world data' and elite athletes, and highlight the key physiological mechanisms that contribute to sex differences in several aspects of physical performance. Physiological mechanisms discussed include those for the varying magnitude of the sex differences in performance involving: (1) absolute muscular strength and power; (2) fatigability of limb muscles as a measure of relative performance; and (3) maximal aerobic power and endurance. The profound sex-based differences in human performance involving strength, power, speed and endurance, and that are largely attributable to the direct and indirect effects of sex-steroid hormones, sex chromosomes and epigenetics, provide a scientific rationale and framework for policy decisions on sex-based categories in sports during puberty and adulthood. Finally, we highlight the sex bias and problem in human performance research of insufficient studies and information on females across many areas of biology and physiology, creating knowledge gaps and opportunities for high-impact studies.
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Affiliation(s)
- Sandra K Hunter
- Movement Science Program, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jonathon W Senefeld
- Department of Kinesiology and Community Health, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
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Dallaway A, Duncan M, Griffen C, Renshaw D, Tallis J, Hattersley J. Age-Related Differences in the Functional Demand Placed on the Lumbar Spine during Walking in Healthy Older versus Younger Men. Geriatrics (Basel) 2024; 9:108. [PMID: 39311233 PMCID: PMC11417934 DOI: 10.3390/geriatrics9050108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2024] [Revised: 08/06/2024] [Accepted: 08/22/2024] [Indexed: 09/26/2024] Open
Abstract
Age-related declines in the musculoskeletal system may place additional demands on the lumbar spine during everyday activities such as walking. This study aimed to investigate age-related differences in the functional demand (FD) of walking on the lumbar spine in older and younger adults. A motion analysis system with integrated force plates was used to acquire kinematic and kinetic data on 12 older (67.3 ± 6.0 years) and 12 younger (24.7 ± 3.1 years) healthy men during walking at a self-selected speed along a 10 m walkway. Isokinetic dynamometry was used to acquire the maximal joint moment capacity of the lumbar spine. The FD of the lumbar spine was calculated as the muscle moment during key phases of the gait cycle (GC) relative to the maximum moment capacity of the lumbar spine. The difference in FD between age groups was not significant (p = 0.07) and there were no significant differences between the young group (YG) and older group (OG) for any individual phase in the GC. Despite the lack of statistical significance, the results indicate that a practical difference may exist, as walking was approximately 20% more functionally demanding on the lumbar spine in the OG compared to the YG. Therefore, older adults may employ modified gait strategies to reduce mechanical load whilst walking to fall within the limits of their maximal force-producing capacity in the lumbar spine, which may have implications for injury risk.
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Affiliation(s)
- Alexander Dallaway
- School of Health and Society, Faculty of Education, Health and Wellbeing, University of Wolverhampton, Millennium City Building, Wulfruna Street, Wolverhampton WV1 1LY, UK
- Coventry NIHR CRF Human Metabolism Research Unit, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Rd, Coventry CV2 2DX, UK;
- Warwickshire Institute for the Study of Diabetes, Endocrinology and Metabolism (WISDEM), University Hospitals Coventry and Warwickshire NHS Trust, Coventry CV2 2DX, UK
| | - Michael Duncan
- Centre for Sport, Exercise and Life Sciences, Institute of Health & Wellbeing, Coventry University, Alison Gingell Building, Priory Street, Coventry CV1 5FB, UK; (M.D.); (C.G.); (D.R.); (J.T.)
- School of Life Sciences, Faculty of Health and Life Sciences, Coventry University, Alison Gingell Building, Priory Street, Coventry CV1 5FB, UK
| | - Corbin Griffen
- Centre for Sport, Exercise and Life Sciences, Institute of Health & Wellbeing, Coventry University, Alison Gingell Building, Priory Street, Coventry CV1 5FB, UK; (M.D.); (C.G.); (D.R.); (J.T.)
| | - Derek Renshaw
- Centre for Sport, Exercise and Life Sciences, Institute of Health & Wellbeing, Coventry University, Alison Gingell Building, Priory Street, Coventry CV1 5FB, UK; (M.D.); (C.G.); (D.R.); (J.T.)
| | - Jason Tallis
- Centre for Sport, Exercise and Life Sciences, Institute of Health & Wellbeing, Coventry University, Alison Gingell Building, Priory Street, Coventry CV1 5FB, UK; (M.D.); (C.G.); (D.R.); (J.T.)
- School of Life Sciences, Faculty of Health and Life Sciences, Coventry University, Alison Gingell Building, Priory Street, Coventry CV1 5FB, UK
| | - John Hattersley
- Coventry NIHR CRF Human Metabolism Research Unit, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Rd, Coventry CV2 2DX, UK;
- Centre for Sport, Exercise and Life Sciences, Institute of Health & Wellbeing, Coventry University, Alison Gingell Building, Priory Street, Coventry CV1 5FB, UK; (M.D.); (C.G.); (D.R.); (J.T.)
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Barbi C, Temesi J, Giuriato G, Laginestra FG, Martignon C, Moro T, Schena F, Venturelli M, Vernillo G. Skeletal muscle fiber type and TMS-induced muscle relaxation in unfatigued and fatigued knee-extensor muscles. Am J Physiol Regul Integr Comp Physiol 2024; 326:R438-R447. [PMID: 38525536 DOI: 10.1152/ajpregu.00174.2023] [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: 07/14/2023] [Revised: 03/14/2024] [Accepted: 03/15/2024] [Indexed: 03/26/2024]
Abstract
The force drop after transcranial magnetic stimulation (TMS) delivered to the motor cortex during voluntary muscle contractions could inform about muscle relaxation properties. Because of the physiological relation between skeletal muscle fiber-type distribution and size and muscle relaxation, TMS could be a noninvasive index of muscle relaxation in humans. By combining a noninvasive technique to record muscle relaxation in vivo (TMS) with the gold standard technique for muscle tissue sampling (muscle biopsy), we investigated the relation between TMS-induced muscle relaxation in unfatigued and fatigued states, and muscle fiber-type distribution and size. Sixteen participants (7F/9M) volunteered to participate. Maximal knee-extensor voluntary isometric contractions were performed with TMS before and after a 2-min sustained maximal voluntary isometric contraction. Vastus lateralis muscle tissue was obtained separately from the participants' dominant limb. Fiber type I distribution and relative cross-sectional area of fiber type I correlated with TMS-induced muscle relaxation at baseline (r = 0.67, adjusted P = 0.01; r = 0.74, adjusted P = 0.004, respectively) and normalized TMS-induced muscle relaxation as a percentage of baseline (r = 0.50, adjusted P = 0.049; r = 0.56, adjusted P = 0.031, respectively). The variance in the normalized peak relaxation rate at baseline (59.8%, P < 0.001) and in the fatigue resistance (23.0%, P = 0.035) were explained by the relative cross-sectional area of fiber type I to total fiber area. Fiber type I proportional area influences TMS-induced muscle relaxation, suggesting TMS as an alternative method to noninvasively inform about skeletal muscle relaxation properties.NEW & NOTEWORTHY Transcranial magnetic stimulation (TMS)-induced muscle relaxation reflects intrinsic muscle contractile properties by interrupting the drive from the central nervous system during voluntary muscle contractions. We showed that fiber type I proportional area influences the TMS-induced muscle relaxation, suggesting that TMS could be used for the noninvasive estimation of muscle relaxation in unfatigued and fatigued human muscles when the feasibility of more direct method to study relaxation properties (i.e., muscle biopsy) is restricted.
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Affiliation(s)
- Chiara Barbi
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - John Temesi
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Gaia Giuriato
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
- Surgical, Medical and Dental Department of Morphological Sciences Related to Transplant, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | | | - Camilla Martignon
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Tatiana Moro
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Federico Schena
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Massimo Venturelli
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States
| | - Gianluca Vernillo
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
- Department of Social Sciences, University of Alberta, Camrose, Alberta, Canada
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Hunter SK, S Angadi S, Bhargava A, Harper J, Hirschberg AL, D Levine B, L Moreau K, J Nokoff N, Stachenfeld NS, Bermon S. The Biological Basis of Sex Differences in Athletic Performance: Consensus Statement for the American College of Sports Medicine. Med Sci Sports Exerc 2023; 55:2328-2360. [PMID: 37772882 DOI: 10.1249/mss.0000000000003300] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
ABSTRACT Biological sex is a primary determinant of athletic performance because of fundamental sex differences in anatomy and physiology dictated by sex chromosomes and sex hormones. Adult men are typically stronger, more powerful, and faster than women of similar age and training status. Thus, for athletic events and sports relying on endurance, muscle strength, speed, and power, males typically outperform females by 10%-30% depending on the requirements of the event. These sex differences in performance emerge with the onset of puberty and coincide with the increase in endogenous sex steroid hormones, in particular testosterone in males, which increases 30-fold by adulthood, but remains low in females. The primary goal of this consensus statement is to provide the latest scientific knowledge and mechanisms for the sex differences in athletic performance. This review highlights the differences in anatomy and physiology between males and females that are primary determinants of the sex differences in athletic performance and in response to exercise training, and the role of sex steroid hormones (particularly testosterone and estradiol). We also identify historical and nonphysiological factors that influence the sex differences in performance. Finally, we identify gaps in the knowledge of sex differences in athletic performance and the underlying mechanisms, providing substantial opportunities for high-impact studies. A major step toward closing the knowledge gap is to include more and equitable numbers of women to that of men in mechanistic studies that determine any of the sex differences in response to an acute bout of exercise, exercise training, and athletic performance.
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Affiliation(s)
- Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, and Athletic and Human Performance Center, Marquette University, Milwaukee, WI
| | | | - Aditi Bhargava
- Department of Obstetrics and Gynecology, Center for Reproductive Sciences, University of California, San Francisco, CA
| | - Joanna Harper
- Loughborough University, Loughborough, UNITED KINGDOM
| | - Angelica Lindén Hirschberg
- Department of Women's and Children's Health, Karolinska Institutet, and Department of Gynecology and Reproductive Medicine, Karolinska University Hospital, Stockholm, SWEDEN
| | - Benjamin D Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and the Department of Internal Medicine, Division of Cardiology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Kerrie L Moreau
- Department of Medicine, Division of Geriatric Medicine, University of Colorado Anschutz Medical Campus, and Eastern Colorado Health Care System, Geriatric Research Education and Clinical Center, Aurora, CO
| | - Natalie J Nokoff
- Department of Pediatrics, Section of Endocrinology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Nina S Stachenfeld
- The John B. Pierce Laboratory and Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT
| | - Stéphane Bermon
- Health and Science Department, World Athletics, Monaco and the LAMHESS, University Côte d'Azur, Nice, FRANCE
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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: 8] [Impact Index Per Article: 8.0] [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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Fitzgerald LF, Bartlett MF, Kent JA. Muscle fatigue, bioenergetic responses and metabolic economy during load- and velocity-based maximal dynamic contractions in young and older adults. Physiol Rep 2023; 11:e15876. [PMID: 37996974 PMCID: PMC10667588 DOI: 10.14814/phy2.15876] [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: 06/02/2023] [Revised: 11/07/2023] [Accepted: 11/07/2023] [Indexed: 11/25/2023] Open
Abstract
We evaluated whether task-dependent, age-related differences in muscle fatigue (contraction-induced decline in normalized power) develop from differences in bioenergetics or metabolic economy (ME; mass-normalized work/mM ATP). We used magnetic resonance spectroscopy to quantify intracellular metabolites in vastus lateralis muscle of 10 young and 10 older adults during two maximal-effort, 4-min isotonic (20% maximal torque) and isokinetic (120°s-1 ) contraction protocols. Fatigue, inorganic phosphate (Pi), and pH (p ≥ 0.213) differed by age during isotonic contractions. However, older had less fatigue (p ≤ 0.011) and metabolic perturbation (lower [Pi], greater pH; p ≤ 0.031) than young during isokinetic contractions. ME was lower in older than young during isotonic contractions (p ≤ 0.003), but not associated with fatigue in either protocol or group. Rather, fatigue during both tasks was linearly related to changes in [H+ ], in both groups. The slope of fatigue versus [H+ ] was 50% lower in older than young during isokinetic contractions (p ≤ 0.023), consistent with less fatigue in older during this protocol. Overall, regardless of age or task type, acidosis, but not ME, was the primary mechanism for fatigue in vivo. The source of the age-related differences in contraction-induced acidosis in vivo remains to be determined, as does the apparent task-dependent difference in the sensitivity of muscle to [H+ ].
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Affiliation(s)
- Liam F. Fitzgerald
- Muscle Physiology Laboratory, Department of KinesiologyUniversity of MassachusettsAmherstMassachusettsUSA
| | - Miles F. Bartlett
- Muscle Physiology Laboratory, Department of KinesiologyUniversity of MassachusettsAmherstMassachusettsUSA
| | - Jane A. Kent
- Muscle Physiology Laboratory, Department of KinesiologyUniversity of MassachusettsAmherstMassachusettsUSA
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11
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Wrucke DJ, Kuplic A, Adam M, Hunter SK, Sundberg CW. Neural and muscular contributions to the age-related loss in power of the knee extensors in men and women. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.24.563851. [PMID: 37961177 PMCID: PMC10634815 DOI: 10.1101/2023.10.24.563851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The mechanisms for the loss in limb muscle power in old (60-79 years) and very old (≥80 years) adults and whether the mechanisms differ between men and women are not well-understood. We compared maximal power of the knee extensor muscles between young, old, and very old men and women and identified the neural and muscular factors contributing to the age-related loss of power. 31 young (22.9±3.0 years, 15 women), 83 old (70.4±4.9 years, 39 women), and 16 very old adults (85.8±4.2 years, 9 women) performed maximal isokinetic contractions at 14 different velocities (30-450°/s) to identify peak power. Voluntary activation (VA) and contractile properties were assessed with transcranial magnetic stimulation to the motor cortex and electrical stimulation of the femoral nerve. The age-related loss in power was ~6.5 W·year-1 for men (R2=0.62, p<0.001), which was a greater rate of decline (p=0.002) than the ~4.2 W·year-1 for women (R2=0.77, p<0.001). Contractile properties were the most closely associated variables with power output for both sexes, such as the rate of torque development of the potentiated twitch (men: R2=0.69, p<0.001; women: R2=0.57, p<0.001). VA was weakly associated with power in women (R2=0.13, p=0.012) but not men (p=0.191), whereas neuromuscular activation (EMG amplitude) during the maximal power contraction was not associated with power in men (p=0.347) or women (p=0.106). These data suggest that the age-related loss in power of the knee extensor muscles is due primarily to factors within the muscle for both sexes, although neural factors may play a minor role in older women.
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Affiliation(s)
- David J. Wrucke
- Exercise and Rehabilitation Sciences Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
| | - Andrew Kuplic
- Exercise and Rehabilitation Sciences Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
| | - Mitchell Adam
- Exercise and Rehabilitation Sciences Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
| | - Sandra K. Hunter
- Exercise and Rehabilitation Sciences Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
- Athletic and Human Performance Research Center, Marquette University, Milwaukee, WI, USA
| | - Christopher W. Sundberg
- Exercise and Rehabilitation Sciences Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
- Athletic and Human Performance Research Center, Marquette University, Milwaukee, WI, USA
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12
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Varesco G, Luneau E, Millet GY, Féasson L, Lapole T, Rozand V. Age-Related Differences between Old and Very Old Men in Performance and Fatigability Are Evident after Cycling but Not Isometric or Concentric Single-Limb Tasks. Med Sci Sports Exerc 2023; 55:1641-1650. [PMID: 37580874 DOI: 10.1249/mss.0000000000003181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
PURPOSE This study aimed to compare performance and fatigability between young (n = 13; 18-30 yr), old (n = 13; 60-80 yr), and very old (n = 12; >80 yr) men during a single-joint isometric (ISO) and concentric (CON) task performed on an isokinetic dynamometer and a cycling (BIKE) task. METHODS Participants randomly performed incremental tasks consisting of stages of 75 contractions (i.e., 120 s, 0.8 s on/0.8 s off) for ISO and CON and 120 s at 37.5 rpm (similar duty cycle) for BIKE. Increments were set as a percentage of body weight. Knee extensor maximal force, voluntary activation, and twitch amplitude were measured at baseline, after each stage, and at task failure (five out of eight contractions below the target force or 6 s in a row at a cadence <37.5 rpm). RESULTS Compared with young men, performance (number of stages) was 24% and 40% lower in old and very old men in ISO, 54% and 59% lower in CON, and 36% and 60% lower in BIKE (all P < 0.05). Performance of old and very old differed only in BIKE (P < 0.01). For the last common stages performed, compared with young, force loss was greater for very old men in ISO and for old and very old men in BIKE (all P < 0.05). Overall, for the last common stage performed and task failure, old and very old men presented similar force loss, alterations in voluntary activation, and twitch amplitude. CONCLUSIONS Our findings reveal that, with workloads relative to body weight, differences in performance between old and very old men could only be observed during BIKE (i.e., the more ecologically valid task). Results from isometric or concentric conditions might not be transferable to dynamic exercise with large muscle masses.
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Affiliation(s)
- Giorgio Varesco
- Université Jean Monnet Saint-Etienne, Lyon 1, Université Savoie Mont-Blanc, Laboratoire Interuniversitaire de Biologie de la Motricité, F-42023, Saint-Etienne, FRANCE
| | - Eric Luneau
- Université Jean Monnet Saint-Etienne, Lyon 1, Université Savoie Mont-Blanc, Laboratoire Interuniversitaire de Biologie de la Motricité, F-42023, Saint-Etienne, FRANCE
| | | | | | - Thomas Lapole
- Université Jean Monnet Saint-Etienne, Lyon 1, Université Savoie Mont-Blanc, Laboratoire Interuniversitaire de Biologie de la Motricité, F-42023, Saint-Etienne, FRANCE
| | - Vianney Rozand
- Université Jean Monnet Saint-Etienne, Lyon 1, Université Savoie Mont-Blanc, Laboratoire Interuniversitaire de Biologie de la Motricité, F-42023, Saint-Etienne, FRANCE
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13
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Nokoff NJ, Senefeld J, Krausz C, Hunter S, Joyner M. Sex Differences in Athletic Performance: Perspectives on Transgender Athletes. Exerc Sport Sci Rev 2023; 51:85-95. [PMID: 37057897 PMCID: PMC10330580 DOI: 10.1249/jes.0000000000000317] [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] [Indexed: 04/15/2023]
Abstract
Sex hormone concentrations, particularly testosterone, are primary determinants of sex-based differences in athletic and sports performance, and this relationship may inform fair competition and participation for athletes. This article describes the sex-based dichotomy in testosterone and the implications for sex-based differences in individual sports performance, including factors that relate to athletic performance for transgender individuals, and areas of future investigation.
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Affiliation(s)
- Natalie J Nokoff
- Division of Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus
| | - Jonathon Senefeld
- Department of Anesthesiology & Perioperative Medicine and Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN
| | - Csilla Krausz
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Sandra Hunter
- Exercise Science Program, Department of Physical Therapy, and Athletic & Human Performance Research Center, Marquette University, Milwaukee, WI
| | - Michael Joyner
- Department of Anesthesiology & Perioperative Medicine and Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN
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14
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Boyer KA, Hayes KL, Umberger BR, Adamczyk PG, Bean JF, Brach JS, Clark BC, Clark DJ, Ferrucci L, Finley J, Franz JR, Golightly YM, Hortobágyi T, Hunter S, Narici M, Nicklas B, Roberts T, Sawicki G, Simonsick E, Kent JA. Age-related changes in gait biomechanics and their impact on the metabolic cost of walking: Report from a National Institute on Aging workshop. Exp Gerontol 2023; 173:112102. [PMID: 36693530 PMCID: PMC10008437 DOI: 10.1016/j.exger.2023.112102] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 01/09/2023] [Accepted: 01/19/2023] [Indexed: 01/22/2023]
Abstract
Changes in old age that contribute to the complex issue of an increased metabolic cost of walking (mass-specific energy cost per unit distance traveled) in older adults appear to center at least in part on changes in gait biomechanics. However, age-related changes in energy metabolism, neuromuscular function and connective tissue properties also likely contribute to this problem, of which the consequences are poor mobility and increased risk of inactivity-related disease and disability. The U.S. National Institute on Aging convened a workshop in September 2021 with an interdisciplinary group of scientists to address the gaps in research related to the mechanisms and consequences of changes in mobility in old age. The goal of the workshop was to identify promising ways to move the field forward toward improving gait performance, decreasing energy cost, and enhancing mobility for older adults. This report summarizes the workshop and brings multidisciplinary insight into the known and potential causes and consequences of age-related changes in gait biomechanics. We highlight how gait mechanics and energy cost change with aging, the potential neuromuscular mechanisms and role of connective tissue in these changes, and cutting-edge interventions and technologies that may be used to measure and improve gait and mobility in older adults. Key gaps in the literature that warrant targeted research in the future are identified and discussed.
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Affiliation(s)
- Katherine A Boyer
- Department of Kinesiology, University of Massachusetts Amherst, MA, USA; Department of Orthopedics and Physical Rehabilitation, University of Massachusetts Medical School, Worcester, MA, USA.
| | - Kate L Hayes
- Department of Kinesiology, University of Massachusetts Amherst, MA, USA
| | | | | | - Jonathan F Bean
- New England GRECC, VA Boston Healthcare System, Boston, MA, USA; Department of PM&R, Harvard Medical School, Boston, MA, USA; Spaulding Rehabilitation Hospital, Boston, MA, USA
| | - Jennifer S Brach
- Department of Physical Therapy, University of Pittsburgh, Pittsburgh, PA, USA
| | - Brian C Clark
- Ohio Musculoskeletal and Neurological Institute and the Department of Biomedical Sciences, Ohio University, Athens, OH, USA
| | - David J Clark
- Brain Rehabilitation Research Center, Malcom Randall VA Medical Center, Gainesville, FL, USA; Department of Physiology and Aging, University of Florida, Gainesville, FL, USA
| | - Luigi Ferrucci
- Intramural Research Program of the National Institute on Aging, NIH, Baltimore, MD, USA
| | - James Finley
- Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USA
| | - Jason R Franz
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC, USA
| | - Yvonne M Golightly
- College of Allied Health Professions, University of Nebraska Medical Center, Omaha, NE, USA; Thurston Arthritis Research Center, Division of Rheumatology, Allergy, and Immunology, Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Tibor Hortobágyi
- Hungarian University of Sports Science, Department of Kinesiology, Budapest, Hungary; Institute of Sport Sciences and Physical Education, University of Pécs, Hungary; Somogy County Kaposi Mór Teaching Hospital, Kaposvár, Hungary; Center for Human Movement Sciences, University of Groningen Medical Center, Groningen, the Netherlands
| | - Sandra Hunter
- Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
| | - Marco Narici
- Neuromuscular Physiology Laboratory, Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Barbara Nicklas
- Section on Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, USA
| | - Thomas Roberts
- Department of Ecology and Evolutionary Biology, Brown University, USA
| | - Gregory Sawicki
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, USA
| | - Eleanor Simonsick
- Intramural Research Program of the National Institute on Aging, NIH, Baltimore, MD, USA
| | - Jane A Kent
- Department of Kinesiology, University of Massachusetts Amherst, MA, USA
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15
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Paris MT, McNeil CJ, Power GA, Rice CL, Dalton BH. Age-related performance fatigability: a comprehensive review of dynamic tasks. J Appl Physiol (1985) 2022; 133:850-866. [PMID: 35952347 DOI: 10.1152/japplphysiol.00319.2022] [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: 11/22/2022] Open
Abstract
Adult ageing is associated with a myriad of changes within the neuromuscular system, leading to reductions in contractile function of old adults. One of the consequences of these age-related neuromuscular adaptations is altered performance fatigability, which can limit the ability of old adults to perform activities of daily living. Whereas age-related fatigability of isometric tasks has been well characterized, considerably less is known about fatigability of old adults during dynamic tasks involving movement about a joint, which provides a more functionally relevant task compared to static contractions. This review provides a comprehensive summary of age-related fatigability in dynamic contractions, where the importance of task specificity is highlighted with a brief discussion of the potential mechanisms responsible for differences in fatigability between young and old adults. The angular velocity of the task is critical for evaluating age-related fatigability, as tasks which constrain angular velocity (i.e., isokinetic) produce equivocal age-related differences in fatigability, whereas tasks involving unconstrained velocity (i.e., isotonic-like) consistently induce greater fatigability of old compared to young adults. These unconstrained velocity tasks, that are more closely associated with natural movements, offer an excellent model to uncover the underlying age-related mechanisms of increased fatigability. Future work evaluating the mechanisms of increased age-related fatigability of dynamic tasks should be evaluated using task-specific contractions (i.e., dynamic), particularly for assessment of spinal and supra-spinal components. Advancing our understanding of age-related fatigability is likely to yield novel insights and approaches for improving mobility limitations in old adults.
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Affiliation(s)
- Michael T Paris
- School of Kinesiology, University of Western Ontario, London, ON, Canada
| | - Chris J McNeil
- School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Geoffrey A Power
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Charles L Rice
- School of Kinesiology, University of Western Ontario, London, ON, Canada.,Department of Anatomy and Cell Biology, University of Western Ontario, London, ON, Canada
| | - Brian H Dalton
- School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
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16
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Vernillo G, Barbi C, Temesi J, Giuriato G, Giuseppe Laginestra F, Martignon C, Schena F, Venturelli M. Reliability of relaxation properties of knee-extensor muscles induced by transcranial magnetic stimulation. Neurosci Lett 2022; 782:136694. [DOI: 10.1016/j.neulet.2022.136694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 10/18/2022]
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17
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Trade-Off Between Maximal Power Output and Fatigue Resistance of the Knee Extensors for Older Men. J Aging Phys Act 2022; 30:1003-1013. [PMID: 35453123 DOI: 10.1123/japa.2021-0384] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 02/15/2022] [Accepted: 02/22/2022] [Indexed: 11/18/2022]
Abstract
This study investigated associations of fatigue resistance determined by an exercise-induced decrease in neuromuscular power with prefatigue neuromuscular strength and power of the knee extensors in 31 older men (65-88 years). A fatigue task consisted of 50 consecutive maximal effort isotonic knee extensions (resistance: 20% of prefatigue isometric maximal voluntary contraction torque) over a 70° range of motion. The average of the peak power values calculated from the 46th to 50th contractions during the fatigue task was normalized to the prefatigue peak power value, which was defined as neuromuscular fatigue resistance. Neuromuscular fatigue resistance was negatively associated with prefatigue maximal power output (r = -.530) but not with prefatigue maximal voluntary contraction torque (r = -.252). This result highlights a trade-off between prefatigue maximal power output and neuromuscular fatigue resistance, implying that an improvement in maximal power output might have a negative impact on neuromuscular fatigue resistance.
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18
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Varesco G, Luneau E, Féasson L, Lapole T, Rozand V. Very old adults show impaired fatigue resistance compared to old adults independently of sex during a knee-extensors isometric test. Exp Gerontol 2022; 161:111732. [DOI: 10.1016/j.exger.2022.111732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 01/31/2022] [Accepted: 02/02/2022] [Indexed: 11/26/2022]
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19
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Ha PL, Peters WB, McGeehan MA, Dalton BH. Age-related reduction in peak power and increased postural displacement variability are related to enhanced vestibular-evoked balance responses in females. Exp Gerontol 2022; 160:111670. [PMID: 35026336 DOI: 10.1016/j.exger.2021.111670] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 12/11/2021] [Accepted: 12/15/2021] [Indexed: 11/04/2022]
Abstract
Adult aging is associated with reductions in muscle function and standing balance control. However, whether sensorimotor function adapts to maintain upright posture in the presence of age-related muscle weakness is unclear. The purpose was to determine whether vestibular control of balance is altered in older compared to younger females and whether vestibular-evoked balance responses are related to muscle power. Eight young (22.6 ± 1.8 years) and eight older (69.7 ± 6.7 years) females stood quietly on a force plate, while subjected to random, continuous electrical vestibular stimulation (EVS; 0-20 Hz, root mean square amplitude: 1.13 mA). Medial gastrocnemius (MG) and tibialis anterior (TA) surface electromyography (EMG) and force plate anterior-posterior (AP) forces were sampled and associated with the EVS signal in the frequency and time domains. Knee extensor function was evaluated using a Biodex multi-joint dynamometer. The weaker, less powerful older females exhibited a 99 and 42% greater medium-latency peak amplitude for the TA and AP force (p < 0.05), respectively, but no other differences were detected for short- and medium-latency peak amplitudes. The TA (<10 Hz) and MG (<4 Hz) EVS-EMG coherence and EVS-AP force coherence (<2 Hz) was greater in older females than young. A strong correlation was detected for AP force medium-latency peak amplitude with center of pressure displacement variability (r = 0.75; p < 0.05) and TA medium-latency peak amplitude (r = 0.86; p < 0.05). Power was negatively correlated with AP force medium-latency peak amplitude (r = -0.47; p < 0.05). Taken together, an increased vestibular control of balance may compensate for an age-related reduction in power and accompanies greater postural instability in older females than young.
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Affiliation(s)
- Phuong L Ha
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Wendy B Peters
- Department of Human Physiology, University of Oregon, Eugene, OR, United States
| | - Michael A McGeehan
- Department of Human Physiology, University of Oregon, Eugene, OR, United States
| | - Brian H Dalton
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada; Department of Human Physiology, University of Oregon, Eugene, OR, United States.
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20
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Tyagi O, Mehta RK. A Methodological Framework to Capture Neuromuscular Fatigue Mechanisms Under Stress. FRONTIERS IN NEUROERGONOMICS 2021; 2:779069. [PMID: 38235237 PMCID: PMC10790877 DOI: 10.3389/fnrgo.2021.779069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/23/2021] [Indexed: 01/19/2024]
Abstract
Neuromuscular fatigue is exacerbated under stress and is characterized by shorter endurance time, greater perceived effort, lower force steadiness, and higher electromyographic activity. However, the underlying mechanisms of fatigue under stress are not well-understood. This review investigated existing methods of identifying central mechanisms of neuromuscular fatigue and the potential mechanisms of the influence of stress on neuromuscular fatigue. We found that the influence of stress on the activity of the prefrontal cortex, which are also involved in exercise regulation, may contribute to exacerbated fatigue under stress. We also found that the traditional methods involve the synchronized use of transcranial magnetic stimulation, peripheral nerve stimulation, and electromyography to identify the contribution of supraspinal fatigue, through measures such as voluntary activation, motor evoked potential, and silent period. However, these popular techniques are unable to provide information about neural alterations upstream of the descending drive that may contribute to supraspinal fatigue development. To address this gap, we propose that functional brain imaging techniques, which provide insights on activation and information flow between brain regions, need to be combined with the traditional measures of measuring central fatigue to fully understand the mechanisms behind the influence of stress on fatigue.
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Affiliation(s)
| | - Ranjana K. Mehta
- Neuroergonomics Lab, Texas A&M University, Industrial and Systems Engineering, College Station, TX, United States
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21
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Delgadillo JD, Sundberg CW, Kwon M, Hunter SK. Fatigability of the knee extensor muscles during high-load fast and low-load slow resistance exercise in young and older adults. Exp Gerontol 2021; 154:111546. [PMID: 34492255 DOI: 10.1016/j.exger.2021.111546] [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: 05/10/2021] [Revised: 08/08/2021] [Accepted: 08/26/2021] [Indexed: 10/20/2022]
Abstract
Resistance exercise training is a cornerstone in preventing age-related declines in muscle mass and strength, and fatigability of limb muscle is important to this adaptive response. It is unknown, however, whether fatigability and the underlying mechanisms differ between different resistance exercise protocols in young and older adults. The purpose of this study was to quantify the fatigability of the knee extensors and identify the mechanisms in 20 young (22.2 ± 1.3 yr, 10 women) and 20 older adults (73.8 ± 5.4 yr, 10 women) elicited by a single session of high- and low-load resistance exercise. One leg completed a high-load protocol with contractions performed as fast as possible (HL-fast, ~80% 1 Repetition Max, 1RM), and the contralateral leg a low-load protocol performed with slow contractions (LL-slow, ~30% 1RM, 6 s concentric, 6 s eccentric). Each exercise involved four sets of eight repetitions. Before and immediately following each set, maximal voluntary isometric contractions (MVC) were performed, and voluntary activation and contractile properties quantified using electrical stimulation. The reduction in MVC was greater following the LL-slow (20%) than the HL-fast (12%, P = 0.004), with no age or sex differences. Similarly, the reduction in the amplitude of the involuntary electrically-evoked twitch was greater in the LL-slow (14%) than the HL-fast (7%, P = 0.014) and correlated with the reduction in MVC (r = 0.546, P < 0.001), whereas voluntary activation decreased only for the LL-slow protocol (5%, P < 0.001). Thus, low-load resistance exercise with slow contractions induced greater fatigability within the muscle than a more traditional high-load resistance protocol for both young and older men and women.
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Affiliation(s)
- Jose D Delgadillo
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
| | - Christopher W Sundberg
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA; Athletic and Human Performance Research Center, Marquette University, Milwaukee, WI, USA
| | - Minhyuk Kwon
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA; Department of Kinesiology & Health Promotion, California State Polytechnic University, Pomona, CA, USA
| | - Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA; Athletic and Human Performance Research Center, Marquette University, Milwaukee, WI, USA.
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22
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Sara LK, Gutsch SB, Hunter SK. The single-leg heel raise does not predict maximal plantar flexion strength in healthy males and females. PLoS One 2021; 16:e0253276. [PMID: 34415915 PMCID: PMC8378718 DOI: 10.1371/journal.pone.0253276] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 06/01/2021] [Indexed: 12/04/2022] Open
Abstract
Introduction The single-leg heel raise test (SLHR) is commonly used in clinical settings to approximate plantar flexor strength, yet this is neither validated nor supported physiologically. The purposes of this study were to: determine (1) associations between SLHR repetitions, maximal plantar flexor strength, and reductions in strength; and (2) whether sex differences exist in performance of the SLHR. Methods Twenty-eight young, healthy participants (14 males,14 females, 19–30 years) performed repeated single-leg heel raises to task failure. Pre- and post-task measures included maximal voluntary isometric contractions (MVIC), and voluntary activation and contractile properties of the plantar flexor muscles, assessed using peripheral electrical stimulation of the tibial nerve. Surface electromyography was recorded for the medial and lateral gastrocnemius, soleus, and anterior tibialis muscles. Results The SLHR resulted in 20.5% reductions in MVIC torque (p<0.001). However, the number of SLHR repetitions was not correlated with either the baseline MVIC (maximal strength; p = 0.979) or the reduction in MVIC following the SLHR (p = 0.23). There were no sex differences in either the number of SLHR repetitions (p = 0.14), baseline MVIC torque (p = 0.198), or the reduction of MVIC (p = 0.14). MVIC decline was positively associated with the reduction in voluntary activation (r = 0.841, p<0.001), but was not associated with the change in twitch amplitude (p = 0.597). Conclusions The SLHR was similar in young males and females yet was a poor predictor of maximal plantar flexor strength but evaluates performance fatigability of the lower extremity specific to dynamic contractions. The reduction in maximal strength at task failure was explained by reduced neural drive to the plantar flexor muscles in both males and females. Impact statement SLHR performance is not a clinical assessment of plantar flexor strength but assesses dynamic lower extremity fatigability that is similar in males and females. Alternate clinical measures for maximal plantar flexion strength need to be developed.
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Affiliation(s)
- Lauren K. Sara
- Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States of America
- * E-mail:
| | - Savannah B. Gutsch
- Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States of America
| | - Sandra K. Hunter
- Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States of America
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Varesco G, Coudy-Gandilhon C, Lapole T, Decourt A, Gueugneau M, Barthélémy JC, Roche F, Bechet D, Féasson L, Rozand V. Association between physical activity, quadriceps muscle performance and biological characteristics of very old men and women. J Gerontol A Biol Sci Med Sci 2021; 77:47-54. [PMID: 34406381 DOI: 10.1093/gerona/glab239] [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: 04/14/2021] [Indexed: 01/23/2023] Open
Abstract
The present study aimed to evaluate the association between physical activity, knee extensors (KE) performance (i.e. isometric strength and fatigability) and biological parameters (i.e. muscle structural, microvascular and metabolic properties) in healthy very old men and women. Thirty very old adults (82±1 yr, 15 women) performed an isometric quadriceps intermittent fatigue (QIF) test for the assessment of KE maximal force, total work (index of absolute performance) and fatigability. Muscle biopsies from the vastus lateralis muscle were collected to assess muscle fibers type and morphology, microvasculature and enzymes activity. Correlation analyses were used to investigate the relationships between physical activity (steps.day -1, actimetry), KE performance, and biological data for each sex separately.Men, compared to women, showed greater total work at the QIF test (44497±8629 N.s vs. 26946±4707 N.s; P<0.001). Steps.day -1 were correlated with total work only for women (r=0.73, P=0.011). In men, steps.day -1 were correlated with the percentage (r=0.57, P=0.033), shape factor (r=0.75, P = 0.002) and capillary tortuosity of type IIX fibers (r=0.59, P=0.035). No other relevant correlations were observed for men or women between steps.day -1 and biological parameters. Physical activity level was positively associated with the capacity of very old women to perform a fatiguing test, but not maximal force production capacity of the KE. Physical activity of very old men was not correlated with muscle performance. We suggest that very old women could be at higher risk of autonomy loss and increasing the steps.day -1 count could provide a sufficient stimulus for adaptations in less active women.
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Affiliation(s)
- Giorgio Varesco
- Université de Lyon, UJM-Saint-Etienne, Laboratoire Interuniversitaire de Biologie de la Motricité, Saint-Etienne, France
| | - Cécile Coudy-Gandilhon
- Université Clermont Auvergne, INRAE, Unité de Nutrition Humaine, CRNH Auvergne, Clermont-Ferrand, France
| | - Thomas Lapole
- Université de Lyon, UJM-Saint-Etienne, Laboratoire Interuniversitaire de Biologie de la Motricité, Saint-Etienne, France
| | - Alice Decourt
- Université Clermont Auvergne, INRAE, Unité de Nutrition Humaine, CRNH Auvergne, Clermont-Ferrand, France
| | - Marine Gueugneau
- Université Clermont Auvergne, INRAE, Unité de Nutrition Humaine, CRNH Auvergne, Clermont-Ferrand, France
| | | | - Frédéric Roche
- Université de Lyon, UJM-Saint-Etienne, Laboratoire SNA-EPIS, Saint-Etienne, France
| | - Daniel Bechet
- Université Clermont Auvergne, INRAE, Unité de Nutrition Humaine, CRNH Auvergne, Clermont-Ferrand, France
| | - Léonard Féasson
- Université de Lyon, UJM-Saint-Etienne, Laboratoire Interuniversitaire de Biologie de la Motricité, Saint-Etienne, France.,Unité de Myologie, Service de Physiologie Clinique et de l'Exercice, Centre Référent Maladies Neuromusculaires Euro-NmD, CHU de Saint-Etienne, France
| | - Vianney Rozand
- Université de Lyon, UJM-Saint-Etienne, Laboratoire Interuniversitaire de Biologie de la Motricité, Saint-Etienne, France
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Senefeld JW, Keenan KG, Ryan KS, D'Astice SE, Negro F, Hunter SK. Greater fatigability and motor unit discharge variability in human type 2 diabetes. Physiol Rep 2021; 8:e14503. [PMID: 32633071 PMCID: PMC7379048 DOI: 10.14814/phy2.14503] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
This study determined the discharge characteristics of motor units from two lower limb muscles before and after fatiguing exercise in people with type 2 diabetes (T2D) with no symptoms of polyneuropathy and activity‐matched controls. Seventeen people with T2D (65.0 ± 5.6 years; 8 women) and 17 controls (63.6 ± 4.5 years; 8 women) performed: (a) intermittent, isometric contractions at 50% maximal voluntary isometric contraction (MVIC) sustained to failure with the ankle dorsiflexors, and (b) a dynamic fatiguing task (30% MVIC load) for 6 min with the knee extensors. Before and after the fatiguing tasks, motor unit characteristics (including coefficient of variation (CV) of interspike intervals (ISI)) were quantified from high‐density electromyography and muscle contractile properties were assessed via electrical stimulation. Fatigability was ~50% greater for people with T2D than controls for the dorsiflexors (time‐to‐failure: 7.3 ± 4.1 vs. 14.3 ± 9.1 min, p = .010) and knee extensors (power reduction: 56.7 ± 11.9 vs. 31.5 ± 25.5%, p < .001). The CV of ISI was greater for the T2D than control group for the tibialis anterior (23.1 ± 11.0 vs. 21.3 ± 10.7%, p < .001) and vastus lateralis (27.8 ± 20.2 vs. 24.5 ± 16.1%, p = .011), but these differences did not change after the fatiguing exercises. People with T2D had greater reductions in the electrically evoked twitch amplitude of the dorsiflexors (8.5 ± 5.1 vs. 4.0 ± 3.4%·min‐1, p = .013) and knee extensors (49.1 ± 10.0 vs. 31.8 ± 15.9%, p = .004) than controls. Although motor unit activity was more variable in people with T2D than controls, the greater fatigability of the T2D group for lower limb muscles was due to mechanisms involving disruption of contractile function of the exercising muscles rather than motor unit behavior.
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Affiliation(s)
- Jonathon W Senefeld
- Exercise Science Program, Marquette University, Milwaukee, WI, USA.,Department of Physical Therapy, Marquette University, Milwaukee, WI, USA.,Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Kevin G Keenan
- Department of Kinesiology, University of Wisconsin, Milwaukee, WI, USA.,Center for Aging and Translational Research, University of Wisconsin, Milwaukee, WI, USA
| | - Kevin S Ryan
- Exercise Science Program, Marquette University, Milwaukee, WI, USA.,Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
| | - Sarah E D'Astice
- Exercise Science Program, Marquette University, Milwaukee, WI, USA.,Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
| | - Sandra K Hunter
- Exercise Science Program, Marquette University, Milwaukee, WI, USA.,Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
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25
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Muscle Performance Changes with Age in Active Women. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18094477. [PMID: 33922474 PMCID: PMC8122865 DOI: 10.3390/ijerph18094477] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 01/16/2023]
Abstract
The purpose of this study was to examine age-related differences in muscle performance in women divided into young (YW, 20–39 years, n = 29) middle-aged (MAW, 40–59 years, n = 33), and older (OW, ≥60 years, n = 40) age groups. Methods: Hand grip strength, vertical jump performance, and knee extensor (KE) strength (0 deg/s, 60 deg/s, and 240 deg/s), speed of movement (SoM; at 1 Nm, 20%, 40%, and 60% isometric strength), and endurance (30-repetition test at 60 degs/s and 240 deg/s) were assessed. Computed tomography-acquired muscle cross-sectional area (mCSA) was measured and included to determine specific strength (KE strength/mCSA). Results: Hand grip strength was similar across groups, while jump performance declined with age (YW and MAW > OW, p < 0.001). KE strength declined significantly with age (all conditions p < 0.01), while specific strength was similar across groups. SoM was significantly higher for YW and MAW compared to OW (both p < 0.01). An age × velocity interaction revealed YW KE endurance was similar between conditions, whereas MAW and OW displayed significantly better endurance during the 60 deg/s condition. OW displayed impaired KE endurance at 240 deg/s (vs. YW and MAW, p < 0.01) but improved at 60 deg/s (vs. YW, p < 0.01). Dynamic torque decline increased with age (YW < OW, p = 0.03) and was associated with intramuscular adipose tissue (r = 0.21, p = 0.04). Conclusions: Performance declines were most evident among OW, but few performance deficits had emerged in MAW. Interestingly, strength declines disappeared after normalizing to mCSA and endurance appears to be velocity-dependent.
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26
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Nuzzo JL, Kennedy DS, Finn HT, Taylor JL. Voluntary activation of knee extensor muscles with transcranial magnetic stimulation. J Appl Physiol (1985) 2021; 130:589-604. [PMID: 33270515 DOI: 10.1152/japplphysiol.00717.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined if transcranial magnetic stimulation (TMS) is a valid tool for assessment of voluntary activation of the knee extensors in healthy individuals. Maximal M-waves (Mmax) of vastus lateralis (VL) were evoked with electrical stimulation of femoral nerve (FNS); Mmax of medial hamstrings (HS) was evoked with electrical stimulation of sciatic nerve branches; motor evoked potentials (MEPs) of VL and HS were evoked with TMS; superimposed twitches (SIT) of knee extensors were evoked with FNS and TMS. In study 1, TMS intensity [69% output (SD: 5)] was optimized for MEP sizes, but guidelines for test validity could not be met. Agonist VL MEPs were too small [51.4% Mmax (SD: 11.9); guideline ≥70% Mmax] and antagonist HS MEPs were too big [16.5% Mmax (SD: 10.3); guideline <10% Mmax]. Consequently, the TMS estimated resting twitch [99.1 N (SD: 37.2)] and FNS resting twitch [142.4 N (SD: 41.8)] were different. In study 2, SITs at 90% maximal voluntary contraction (MVC) were similar between TMS [16.1 N (SD: 10.3)] and FNS [20.9 N (SD: 16.7)], when TMS intensity was optimized for this purpose, suggesting a procedure that combines TMS SITs with FNS resting twitches could be valid. In study 3, which tested the TMS intensity [56% output (SD: 18)] that evoked the largest SIT at 90% MVC, voluntary activation from TMS [87.3% (SD: 7.1)] and FNS [84.5% (SD: 7.6)] was different. In sum, the contemporary procedure for TMS-based voluntary activation of the knee extensors is invalid. A modified procedure improves validity but only in individuals who meet rigorous inclusion criteria for SITs and MEPs.NEW & NOTEWORTHY We discovered that the contemporary procedure for assessing voluntary activation of the knee extensor muscles with transcranial magnetic stimulation (TMS) is invalid. TMS activates too few agonist quadriceps motoneurons and too many antagonist hamstrings motoneurons to estimate the resting twitch accurately. A modified procedure, in which TMS-evoked superimposed twitches are considered together with the resting twitch from femoral nerve stimulation, is valid but only in select individuals who meet rigorous eligibility criteria.
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Affiliation(s)
- James L Nuzzo
- Neuroscience Research Australia, Randwick, Australia
| | - David S Kennedy
- Graduate School of Health, University of Technology Sydney, Sydney, Australia
| | | | - Janet L Taylor
- Neuroscience Research Australia, Randwick, Australia.,School of Medical and Health Sciences, Edith Cowan University, Perth, Australia
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27
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Fitzgerald LF, Ryan MM, Bartlett MF, Miehm JD, Kent JA. Muscle architecture, voluntary activation, and low-frequency fatigue do not explain the greater fatigue of older compared with young women during high-velocity contractions. PLoS One 2020; 15:e0234217. [PMID: 33141870 PMCID: PMC7608879 DOI: 10.1371/journal.pone.0234217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 10/18/2020] [Indexed: 11/18/2022] Open
Abstract
Although high-velocity contractions elicit greater muscle fatigue in older than young adults, the cause of this difference is unclear. We examined the potential roles of resting muscle architecture and baseline contractile properties, as well as changes in voluntary activation and low-frequency fatigue in response to high-velocity knee extensor work. Vastus lateralis muscle architecture was determined in quiescent muscle by ultrasonography in 8 young (23.4±1.8 yrs) and 8 older women (69.6±1.1). Maximal voluntary dynamic (MVDC) and isometric (MVIC), and stimulated (80Hz and 10Hz, 500ms) isometric contractions were performed before and immediately after 120 MVDCs (240°.s-1, one every 2s). Architecture variables did not differ between groups (p≥0.209), but the half-time of torque relaxation (T1/2) was longer in older than young women at baseline (151.9±6.0 vs. 118.8±4.4 ms, respectively, p = 0.001). Older women fatigued more than young (to 33.6±4.7% vs. 55.2±4.2% initial torque, respectively; p = 0.004), with no evidence of voluntary activation failure (ΔMVIC:80Hz torque) in either group (p≥0.317). Low-frequency fatigue (Δ10:80Hz torque) occurred in both groups (p<0.001), as did slowing of T1/2 (p = 0.001), with no differences between groups. Baseline T1/2 was inversely associated with fatigue in older (r2 = 0.584, p = 0.045), but not young women (r2 = 0.147, p = 0.348). These results indicate that differences in muscle architecture, voluntary activation, and low-frequency fatigue do not explain the greater fatigue of older compared with young women during high-velocity contractions. The inverse association between baseline T1/2 and fatigue in older women suggests that factors related to slower muscle contractile properties may be protective against fatigue during fast, repetitive contractions in aging.
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Affiliation(s)
- Liam F. Fitzgerald
- Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts, United States of America
| | - Margaret M. Ryan
- Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts, United States of America
| | - Miles F. Bartlett
- Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts, United States of America
| | - Jules D. Miehm
- Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts, United States of America
| | - Jane A. Kent
- Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts, United States of America
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28
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Kwon M, Senefeld JW, Hunter SK. Attenuated activation of knee extensor muscles during fast contractions in older men and women. Eur J Appl Physiol 2020; 120:2289-2299. [PMID: 32789699 DOI: 10.1007/s00421-020-04451-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 07/30/2020] [Indexed: 01/07/2023]
Abstract
AIM Reduced physical function and increased risk of falls in older adults are accompanied by age-related reductions in torque development of leg muscles, although the mechanisms and potential sex differences are not understood. PURPOSE To determine the mechanistic origins (neural vs. muscular) for the age-related reduction in torque development, we compared the peak rates of torque development (RTD) during electrically-evoked and fast voluntary contractions of the knee extensors between young and older men and women. METHODS Sets of single- and double-pulse electrical stimulations evoked contractions of the knee extensor muscles in 20 young (23.0 ± 0.8 years; 10 women) and 20 older adults (78.2 ± 1.5 years; 10 women), followed by voluntary isometric knee extension contractions with torque development as fast as possible that matched the torque during electrically-evoked contraction (10-40% maximal torque). RESULTS Peak RTD during fast-voluntary contractions was 41% less than electrically-evoked contractions (p < 0.001), but more so for older adults (44%) than young (38%, p = 0.04), with no sex differences. Peak RTD during fast-voluntary contractions was more variable between contractions for the older than young adults (77%MVC s-1 vs. 47%MVC s-1, p < 0.001). Additionally, older women exhibited greater variability than older men (81%MVC s-1 vs. 72%MVC s-1, p = 0.04) with no sex-related differences within the young adults. CONCLUSION Older adults had slower and more variable RTD during voluntary contractions than young adults, particularly older women. The limited age-related differences in electrically-evoked RTD suggest the primary mechanism for the slower torque development of the knee extensor muscles in older men and women involve reduced neural activation.
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Affiliation(s)
- MinHyuk Kwon
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA.,Department of Kinesiology and Health Promotion, California State Polytechnic University, Pomona, CA, USA
| | - Jonathon W Senefeld
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA.,Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI, USA.
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29
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Akagi R, Hinks A, Power GA. Differential changes in muscle architecture and neuromuscular fatigability induced by isometric resistance training at short and long muscle-tendon unit lengths. J Appl Physiol (1985) 2020; 129:173-184. [PMID: 32552430 DOI: 10.1152/japplphysiol.00280.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
We evaluated the effects of differential muscle architectural adaptations on neuromuscular fatigue resistance. Seven young males and six females participated in this study. Using a longitudinal within-subject design, legs were randomly assigned to perform isometric training of the tibialis anterior (TA) three times per week for 8 wk at a short (S-group) or long muscle-tendon unit length (L-group). Before and following training, fascicle length (FL) and pennation angle (PA) of the TA were assessed. As well, fatigue-related time course changes in isometric maximal voluntary contraction (MVC) torque and isotonic peak power (20% MVC resistance) were determined before, immediately after, and 1, 2, 5, and 10 min following task failure. The fatiguing task consisted of repeated maximal effort isotonic (20% MVC resistance) contractions over a 40° range of motion until the participant reached a 40% reduction in peak power. Although there was no clear improvement in neuromuscular fatigue resistance following training in either group (P = 0.081; S-group: ∼20%; L-group: ∼51%), the change in neuromuscular fatigue resistance was related positively to the training-induced increase in PA (∼6%, P < 0.001) in the S-group (r = 0.739, P = 0.004) and negatively to the training-induced increase in FL (∼4%, P = 0.001) in the L-group (r = -0.568, P = 0.043). Both groups recovered similarly for MVC torque and peak power after the fatiguing task as compared with before training. We suggest that the relationships between the changes in muscle architecture and neuromuscular fatigue resistance depend on the muscle-tendon unit lengths at which the training is performed.NEW & NOTEWORTHY Eight weeks of isometric training at a long or short muscle-tendon unit length increased and did not change fascicle length, respectively. The "width" of the torque-angle relationship plateau became broader following isometric training at the long length. Despite marked differences in muscle architecture and functional adaptations between the groups, there was only a small-magnitude improvement in neuromuscular fatigue resistance, which was surprisingly negatively related to increased fascicle length in the long length-training group.
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Affiliation(s)
- Ryota Akagi
- College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama, Japan.,Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, Ontario, Canada
| | - Avery Hinks
- Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, Ontario, Canada
| | - Geoffrey A Power
- Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, Ontario, Canada
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30
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Age-related neuromuscular fatigue and recovery after cycling: Measurements in isometric and dynamic modes. Exp Gerontol 2020; 133:110877. [DOI: 10.1016/j.exger.2020.110877] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 02/08/2020] [Accepted: 02/10/2020] [Indexed: 01/02/2023]
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31
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Teigen LE, Sundberg CW, Kelly LJ, Hunter SK, Fitts RH. Ca 2+ dependency of limb muscle fiber contractile mechanics in young and older adults. Am J Physiol Cell Physiol 2020; 318:C1238-C1251. [PMID: 32348175 DOI: 10.1152/ajpcell.00575.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Age-induced declines in skeletal muscle contractile function have been attributed to multiple cellular factors, including lower peak force (Po), decreased Ca2+ sensitivity, and reduced shortening velocity (Vo). However, changes in these cellular properties with aging remain unresolved, especially in older women, and the effect of submaximal Ca2+ on contractile function is unknown. Thus, we compared contractile properties of muscle fibers from 19 young (24 ± 3 yr; 8 women) and 21 older adults (77 ± 7 yr; 7 women) under maximal and submaximal Ca2+ and assessed the abundance of three proteins thought to influence Ca2+ sensitivity. Fast fiber cross-sectional area was ~44% larger in young (6,479 ± 2,487 µm2) compared with older adults (4,503 ± 2,071 µm2, P < 0.001), which corresponded with a greater absolute Po (young = 1.12 ± 0.43 mN; old = 0.79 ± 0.33 mN, P < 0.001). There were no differences in fast fiber size-specific Po, indicating the age-related decline in force was explained by differences in fiber size. Except for fast fiber size and absolute Po, no age or sex differences were observed in Ca2+ sensitivity, rate of force development (ktr), or Vo in either slow or fast fibers. Submaximal Ca2+ depressed ktr and Vo, but the effects were not altered by age in either sex. Contrary to rodent studies, regulatory light chain (RLC) and myosin binding protein-C abundance and RLC phosphorylation were unaltered by age or sex. These data suggest the age-associated reductions in contractile function are primarily due to the atrophy of fast fibers and that caution is warranted when extending results from rodent studies to humans.
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Affiliation(s)
- Laura E Teigen
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| | - Christopher W Sundberg
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin.,Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin
| | - Lauren J Kelly
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
| | - Sandra K Hunter
- Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin
| | - Robert H Fitts
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
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Rozand V, Sundberg CW, Hunter SK, Smith AE. Age-related Deficits in Voluntary Activation: A Systematic Review and Meta-analysis. Med Sci Sports Exerc 2020; 52:549-560. [PMID: 31688647 PMCID: PMC8015244 DOI: 10.1249/mss.0000000000002179] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Whether there are age-related differences in neural drive during maximal effort contractions is not clear. This review determined the effect of age on voluntary activation during maximal voluntary isometric contractions. The literature was systematically reviewed for studies reporting voluntary activation quantified with the interpolated twitch technique (ITT) or central activation ratio (CAR) during isometric contractions in young (18-35 yr) and old adults (>60 yr; mean, ≥65 yr). Of the 2697 articles identified, 54 were eligible for inclusion in the meta-analysis. Voluntary activation was assessed with electrical stimulation and transcranial magnetic stimulation on five different muscle groups. Random-effects meta-analysis revealed lower activation in old compared with young adults (d = -0.45; 95% confidence interval, -0.62 to -0.29; P < 0.001), with moderate heterogeneity (52.4%). To uncover the sources of heterogeneity, subgroup analyses were conducted for muscle group, calculation method (ITT or CAR), and stimulation type (electrical stimulation or transcranial magnetic stimulation) and number (single, paired, or train stimulations). The age-related reduction in voluntary activation occurred for all muscle groups investigated except the ankle dorsiflexors. Both ITT and CAR demonstrated an age-related reduction in voluntary activation of the elbow flexors, knee extensors, and plantar flexors. ITT performed with paired and train stimulations showed lower activation for old than young adults, with no age difference for the single electrical stimulation. Together, the meta-analysis revealed that healthy older adults have a reduced capacity to activate some upper and lower limb muscles during maximal voluntary isometric contractions; however, the effect was modest and best assessed with at least paired stimulations to detect the difference.
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Affiliation(s)
- Vianney Rozand
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI
| | - Christopher W Sundberg
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI
| | - Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, WI
| | - Ashleigh E Smith
- Alliance for Research in Exercise, Nutrition and Activity, School of Health Sciences, University of South Australia, Adelaide, SA, AUSTRALIA
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Yang J, Xu H, Liang J, Jeong J, Xu T. Monitoring the training dose and acute fatigue response during elbow flexor resistance training using a custom-made resistance band. PeerJ 2020; 8:e8689. [PMID: 32140314 PMCID: PMC7047867 DOI: 10.7717/peerj.8689] [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: 08/12/2019] [Accepted: 02/05/2020] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Home-based resistance training offers an alternative to traditional, hospital-based or rehabilitation center-based resistance training and has attracted much attention recently. However, without the supervision of a therapist or the assistance of an exercise monitoring system, one of the biggest challenges of home-based resistance training is that the therapist may not know if the patient has performed the exercise as prescribed. A lack of objective measurements limits the ability of researchers to evaluate the outcome of exercise interventions and choose suitable training doses. OBJECTIVE To create an automated and objective method for segmenting resistance force data into contraction phase-specific segments and calculate the repetition number and time-under-tension (TUT) during elbow flexor resistance training. A pilot study was conducted to evaluate the performance of the segmentation algorithm and to show the capability of the system in monitoring the compliance of patients to a prescribed training program in a practical resistance training setting. METHODS Six subjects (three male and three female) volunteered to participate in a fatigue and recovery experiment (5 min intermittent submaximal contraction (ISC); 1 min rest; 2 min ISC). A custom-made resistance band was used to help subjects perform biceps curl resistance exercises and the resistance was recorded through a load cell. The maximum and minimum values of the force-derivative were obtained as distinguishing features and a segmentation algorithm was proposed to divide the biceps curl cycle into concentric, eccentric and isometric contraction, and rest phases. Two assessors, who were unfamiliar with the study, were recruited to manually pick the visually observed cut-off point between two contraction phases and the TUT was calculated and compared to evaluate performance of the segmentation algorithm. RESULTS The segmentation algorithm was programmatically implemented and the repetition number and contraction-phase specific TUT were calculated. During isometric, the average TUT (3.75 ± 0.62 s) was longer than the prescribed 3 s, indicating that most subjects did not perform the exercise as prescribed. There was a good TUT agreement and contraction segment agreement between the proposed algorithm and the assessors. CONCLUSION The good agreement in TUT between the proposed algorithm and the assessors indicates that the proposed algorithm can correctly segment the contraction into contraction phase-specific parts, thereby providing clinicians and researchers with an automated and objective method for quantifying home-based elbow flexor resistance training. The instrument is easy to use and cheap, and the segmentation algorithm is programmatically implemented, indicating good application prospect of the method in a practical setting.
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Affiliation(s)
- Jingjing Yang
- Faculty of Civil Aviation and Aeroautics, Kunming University of Science and Technology, Kunming, China
| | - Hongbin Xu
- College of Mechanical Engineering, Chongqing University of Technology, Chongqing, China
| | - Juke Liang
- College of Mechanical Engineering, Chongqing University of Technology, Chongqing, China
| | - Jongyeob Jeong
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Ube, Japan
| | - Taojin Xu
- College of Mechanical Engineering, Chongqing University of Technology, Chongqing, China
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Ube, Japan
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Fenech RK, Ryan CR. Mechanistic insights on muscle fatigue in ageing adults. J Physiol 2019; 597:5749-5750. [PMID: 31598968 DOI: 10.1113/jp278684] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/07/2019] [Indexed: 11/08/2022] Open
Affiliation(s)
- Rachel K Fenech
- Department of Health Sciences, Brock University, St Catharines, ON, Canada
| | - Chantal R Ryan
- Department of Health Sciences, Brock University, St Catharines, ON, Canada
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35
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Hostrup M, Bangsbo J, Cairns SP. Inorganic phosphate, protons and diprotonated phosphate may contribute to the exacerbated muscle fatigue in older adults. J Physiol 2019; 597:4865-4866. [DOI: 10.1113/jp278369] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Morten Hostrup
- Section of Integrative PhysiologyDepartment of NutritionExercise and SportsUniversity of Copenhagen Copenhagen Denmark
| | - Jens Bangsbo
- Section of Integrative PhysiologyDepartment of NutritionExercise and SportsUniversity of Copenhagen Copenhagen Denmark
| | - Simeon P. Cairns
- SPRINZSchool of Sport and RecreationAuckland University of Technology Auckland New Zealand
- Health and Rehabilitation Research InstituteAuckland University of Technology Auckland New Zealand
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Sundberg CW, Prost RW, Fitts RH, Hunter SK. Bioenergetic basis for the increased fatigability with ageing. J Physiol 2019; 597:4943-4957. [PMID: 31018011 DOI: 10.1113/jp277803] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 04/18/2019] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS The mechanisms for the age-related increase in fatigability during dynamic exercise remain elusive. We tested whether age-related impairments in muscle oxidative capacity would result in a greater accumulation of fatigue causing metabolites, inorganic phosphate (Pi ), hydrogen (H+ ) and diprotonated phosphate (H2 PO4 - ), in the muscle of old compared to young adults during a dynamic knee extension exercise. The age-related increase in fatigability (reduction in mechanical power) of the knee extensors was closely associated with a greater accumulation of metabolites within the working muscle but could not be explained by age-related differences in muscle oxidative capacity. These data suggest that the increased fatigability in old adults during dynamic exercise is primarily determined by age-related impairments in skeletal muscle bioenergetics that result in a greater accumulation of metabolites. ABSTRACT The present study aimed to determine whether the increased fatigability in old adults during dynamic exercise is associated with age-related differences in skeletal muscle bioenergetics. Phosphorus nuclear magnetic resonance spectroscopy was used to quantify concentrations of high-energy phosphates and pH in the knee extensors of seven young (22.7 ± 1.2 years; six women) and eight old adults (76.4 ± 6.0 years; seven women). Muscle oxidative capacity was measured from the phosphocreatine (PCr) recovery kinetics following a 24 s maximal voluntary isometric contraction. The fatiguing exercise consisted of 120 maximal velocity contractions (one contraction per 2 s) against a load equivalent to 20% of the maximal voluntary isometric contraction. The PCr recovery kinetics did not differ between young and old adults (0.023 ± 0.007 s-1 vs. 0.019 ± 0.004 s-1 , respectively). Fatigability (reductions in mechanical power) of the knee extensors was ∼1.8-fold greater with age and was accompanied by a greater decrease in pH (young = 6.73 ± 0.09, old = 6.61 ± 0.04) and increases in concentrations of inorganic phosphate, [Pi ], (young = 22.7 ± 4.8 mm, old = 32.3 ± 3.6 mm) and diprotonated phosphate, [H2 PO4 - ], (young = 11.7 ± 3.6 mm, old = 18.6 ± 2.1 mm) at the end of the exercise in old compared to young adults. The age-related increase in power loss during the fatiguing exercise was strongly associated with intracellular pH (r = -0.837), [Pi ] (r = 0.917) and [H2 PO4 - ] (r = 0.930) at the end of the exercise. These data suggest that the age-related increase in fatigability during dynamic exercise has a bioenergetic basis and is explained by an increased accumulation of metabolites within the muscle.
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Affiliation(s)
- Christopher W Sundberg
- Department of Biological Sciences, Marquette University, Milwaukee, WI, USA.,Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
| | - Robert W Prost
- Department of Radiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Robert H Fitts
- Department of Biological Sciences, Marquette University, Milwaukee, WI, USA
| | - Sandra K Hunter
- Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
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37
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Sundberg CW, Fitts RH. Bioenergetic basis of skeletal muscle fatigue. CURRENT OPINION IN PHYSIOLOGY 2019; 10:118-127. [PMID: 31342000 DOI: 10.1016/j.cophys.2019.05.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Energetic demand from high-intensity exercise can easily exceed ATP synthesis rates of mitochondria leading to a reliance on anaerobic metabolism. The reliance on anaerobic metabolism results in the accumulation of intracellular metabolites, namely inorganic phosphate (Pi) and hydrogen (H+), that are closely associated with exercise-induced reductions in power. Cellular and molecular studies have revealed several steps where these metabolites impair contractile function demonstrating a causal role in fatigue. Elevated Pi or H+ directly inhibits force and power of the cross-bridge and decreases myofibrillar Ca2+ sensitivity, whereas Pi also inhibits Ca2+ release from the sarcoplasmic reticulum (SR). When both metabolites are elevated, they act synergistically to cause marked reductions in power, indicating that fatigue during high-intensity exercise has a bioenergetic basis.
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Affiliation(s)
- Christopher W Sundberg
- Department of Biological Sciences, Marquette University, Milwaukee, WI.,Department of Physical Therapy, Marquette University, Milwaukee, WI
| | - Robert H Fitts
- Department of Biological Sciences, Marquette University, Milwaukee, WI
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Coen PM, Musci RV, Hinkley JM, Miller BF. Mitochondria as a Target for Mitigating Sarcopenia. Front Physiol 2019; 9:1883. [PMID: 30687111 PMCID: PMC6335344 DOI: 10.3389/fphys.2018.01883] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 12/12/2018] [Indexed: 12/14/2022] Open
Abstract
Sarcopenia is the loss of muscle mass, strength, and physical function that is characteristic of aging. The progression of sarcopenia is gradual but may be accelerated by periods of muscle loss during physical inactivity secondary to illness or injury. The loss of mobility and independence and increased comorbidities associated with sarcopenia represent a major healthcare challenge for older adults. Mitochondrial dysfunction and impaired proteostatic mechanisms are important contributors to the complex etiology of sarcopenia. As such, interventions that target improving mitochondrial function and proteostatic maintenance could mitigate or treat sarcopenia. Exercise is currently the only effective option to treat sarcopenia and does so, in part, by improving mitochondrial energetics and protein turnover. Exercise interventions also serve as a discovery tool to identify molecular targets for development of alternative therapies to treat sarcopenia. In summary, we review the evidence linking mitochondria and proteostatic maintenance to sarcopenia and discuss the therapeutic potential of interventions addressing these two factors to mitigate sarcopenia.
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Affiliation(s)
- Paul M Coen
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, FL, United States
| | - Robert V Musci
- Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, United States
| | - J Matthew Hinkley
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, FL, United States
| | - Benjamin F Miller
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
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Foster AD, Fitzgerald LF, Bartlett MF, Straight CR. Potential cellular and energetic mechanisms for age-related differences in skeletal muscle fatigue. J Physiol 2018; 597:373-374. [PMID: 30408194 DOI: 10.1113/jp277060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Aurora D Foster
- Department of Kinesiology, University of Massachusetts, Amherst, MA, USA
| | - Liam F Fitzgerald
- Department of Kinesiology, University of Massachusetts, Amherst, MA, USA
| | - Miles F Bartlett
- Department of Kinesiology, University of Massachusetts, Amherst, MA, USA
| | - Chad R Straight
- Department of Kinesiology, University of Massachusetts, Amherst, MA, USA
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40
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Sundberg CW, Hunter SK, Trappe SW, Smith CS, Fitts RH. Effects of elevated H + and P i on the contractile mechanics of skeletal muscle fibres from young and old men: implications for muscle fatigue in humans. J Physiol 2018; 596:3993-4015. [PMID: 29806714 PMCID: PMC6117549 DOI: 10.1113/jp276018] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Accepted: 04/27/2018] [Indexed: 01/09/2023] Open
Abstract
KEY POINTS The mechanisms responsible for the loss in muscle power and increased fatigability with ageing are unresolved. We show that the contractile mechanics of fibres from the vastus lateralis of old men were well-preserved compared to those of young men, but the selective loss of fast myosin heavy chain II muscle was strongly associated with age-related decrements in whole-muscle strength and power. We reveal that the combination of acidosis (H+ ) and inorganic phosphate (Pi ) is an important mediator of muscle fatigue in humans by inhibiting the low- to high-force state of the cross-bridge cycle and peak power, but the depressive effects of these ions on cross-bridge function were similar in fibres from young and old men. These findings suggest that the age-related loss in muscle power is primarily determined by the atrophy of fast fibres, but the age-related increased fatigability cannot be explained by an increased sensitivity of the cross-bridge to H+ and Pi . ABSTRACT The present study aimed to identify the mechanisms responsible for the loss in muscle power and increased fatigability with ageing by integrating measures of whole-muscle function with single fibre contractile mechanics. After adjusting for the 22% smaller muscle mass in old (73-89 years, n = 6) compared to young men (20-29 years, n = 6), isometric torque and power output of the knee extensors were, respectively, 38% and 53% lower with age. Fatigability was ∼2.7-fold greater with age and strongly associated with reductions in the electrically-evoked contractile properties. To test whether cross-bridge mechanisms could explain age-related decrements in knee extensor function, we exposed myofibres (n = 254) from the vastus lateralis to conditions mimicking quiescent muscle and fatiguing levels of acidosis (H+ ) (pH 6.2) and inorganic phosphate (Pi ) (30 mm). The fatigue-mimicking condition caused marked reductions in force, shortening velocity and power and inhibited the low- to high-force state of the cross-bridge cycle, confirming findings from non-human studies that these ions act synergistically to impair cross-bridge function. Other than severe age-related atrophy of fast fibres (-55%), contractile function and the depressive effects of the fatigue-mimicking condition did not differ in fibres from young and old men. The selective loss of fast myosin heavy chain II muscle was strongly associated with the age-related decrease in isometric torque (r = 0.785) and power (r = 0.861). These data suggest that the age-related loss in muscle strength and power are primarily determined by the atrophy of fast fibres, but the age-related increased fatigability cannot be explained by an increased sensitivity of the cross-bridge to H+ and Pi .
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Affiliation(s)
- Christopher W. Sundberg
- Exercise Science ProgramMilwaukeeWIUSA
- Clinical & Translational Rehabilitation Health Sciences ProgramDepartment of Physical TherapyMarquette UniversityMilwaukeeWIUSA
| | - Sandra K. Hunter
- Exercise Science ProgramMilwaukeeWIUSA
- Clinical & Translational Rehabilitation Health Sciences ProgramDepartment of Physical TherapyMarquette UniversityMilwaukeeWIUSA
| | - Scott W. Trappe
- Human Performance LaboratoryBall State UniversityMuncieINUSA
| | | | - Robert H. Fitts
- Department of Biological SciencesMarquette UniversityMilwaukeeWIUSA
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Collins JD, O'Sullivan L. Age and sex related differences in shoulder abduction fatigue. BMC Musculoskelet Disord 2018; 19:280. [PMID: 30081890 PMCID: PMC6080419 DOI: 10.1186/s12891-018-2191-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 07/13/2018] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Injury prevalence data commonly indicate trends of higher rates of work-related musculoskeletal disorders in older workers over their younger counterparts, and for females more than males. The purpose of this study was to investigate age and sex-related differences in manifestations of shoulder muscle fatigue in a cohort of young and older working age males and females, in a single experiment design allowing for direct comparison of the fatigue effects between the target groups. METHODS We report upper trapezius muscle fibre Conduction Velocity (CV) as an indicative measure of muscle fatigability, and isometric endurance time, at three levels of shoulder abduction lifting force set relative to participants' maximal strength. RESULTS Upper trapezius conduction velocity was significantly different between the young and old groups (p = 0.002) as well as between males and females (p = 0.016). Shoulder abduction endurance time was affected by age (P = 0.024) but not sex (p = 0.170). CONCLUSIONS The study identified age-related improvement in muscle fatigue resistance and increased resistance for females over males, contrary to injury prevalence trends. The muscle fatigue effects are most likely explained by muscle fibre type composition. Experimental fatigue treatments of the upper trapezius were tested at exposures relative to the participants' strength. Absolute strength is higher when young and is generally higher for males. The findings of this study point towards age and sex-related differences in strength rather than in muscle fatigue resistance as a primary cause for the differences in the injury trends.
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Affiliation(s)
- John D Collins
- School of Design, University of Limerick, Limerick, Ireland
| | - Leonard O'Sullivan
- School of Design and Health Research Institute, University of Limerick, Limerick, Ireland.
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Senefeld J, Magill SB, Harkins A, Harmer AR, Hunter SK. Mechanisms for the increased fatigability of the lower limb in people with type 2 diabetes. J Appl Physiol (1985) 2018; 125:553-566. [DOI: 10.1152/japplphysiol.00160.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fatiguing exercise is the basis of exercise training and a cornerstone of management of type 2 diabetes mellitus (T2D); however, little is known about the fatigability of limb muscles and the involved mechanisms in people with T2D. The purpose of this study was to compare fatigability of knee extensor muscles between people with T2D and controls without diabetes and determine the neural and muscular mechanisms for a dynamic fatiguing task. Seventeen people with T2D [ten men and seven women: 59.6 (9.0) yr] and twenty-one age-, body mass index-, and physical activity-matched controls [eleven men and ten women: 59.5 (9.6) yr] performed one hundred twenty high-velocity concentric contractions (one contraction/3 s) with a load equivalent to 20% maximal voluntary isometric contraction (MVIC) torque with the knee extensors. Transcranial magnetic stimulation (TMS) and electrical stimulation of the quadriceps were used to assess voluntary activation and contractile properties. People with T2D had larger reductions than controls in power during the fatiguing task [42.8 (24.2) vs. 26.4 (15.0)%; P < 0.001] and MVIC torque after the fatiguing task [37.6 (18.2) vs. 26.4 (12.1)%; P = 0.04]. People with T2D had greater reductions than controls in the electrically evoked twitch amplitude after the fatiguing task [44.0 (20.4) vs. 35.4 (12.1)%, respectively; P = 0.01]. However, the decrease in voluntary activation was similar between groups when assessed with electrical stimulation [12.1 (2.6) vs. 12.4 (4.4)% decrease; P = 0.84] and TMS ( P = 0.995). A greater decline in MVIC torque was associated with larger reductions of twitch amplitude ( r2 = 0.364, P = 0.002). Although neural mechanisms contributed to fatigability, contractile mechanisms were responsible for the greater knee extensor fatigability in men and women with T2D compared with healthy controls. NEW & NOTEWORTHY Transcranial magnetic stimulation and percutaneous muscle stimulation were used to determine the contributions of neural and contractile mechanisms of fatigability of the knee extensor muscles after a dynamic fatiguing task in men and women with type 2 diabetes (T2D) and healthy age-, body mass index-, and physical activity-matched controls. Although neural and contractile mechanisms contributed to greater fatigability of people with T2D, fatigability was primarily associated with impaired contractile mechanisms and glycemic control.
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Affiliation(s)
- Jonathon Senefeld
- Program in Exercise Science, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin
| | - Steven B. Magill
- Division of Endocrinology, Metabolism, and Clinical Nutrition, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - April Harkins
- Department of Clinical Laboratory Science, Marquette University, Milwaukee, Wisconsin
| | - Alison R. Harmer
- Musculoskeletal Health Research Group, Faculty of Health Sciences, The University of Sydney, Lidcombe, New South Wales, Australia
| | - Sandra K. Hunter
- Program in Exercise Science, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin
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