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Paris MT, Rice CL. Voluntary activation of human knee extensors during isotonic shortening contractions. Eur J Appl Physiol 2024; 124:2171-2181. [PMID: 38436666 DOI: 10.1007/s00421-024-05441-2] [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: 10/16/2023] [Accepted: 02/16/2024] [Indexed: 03/05/2024]
Abstract
PURPOSE The interpolated twitch technique (ITT) is often used to assess voluntary activation during isometric contractions; however, this may have limited relevance to dynamic contractions. Although the ITT has been applied to relatively slow isokinetic contractions (< 150°/s), it has received limited consideration during unconstrained velocity (i.e., isotonic) contractions, despite their relevance to natural movements. Here, we explored the ITT during isotonic knee extension contractions using a modified dynamometer. METHODS Young males (n = 6) and females (n = 4) performed isometric and isotonic knee extension contractions of sub-maximal and maximal intensities with doublet (150 Hz) muscle belly stimulations to assess voluntary activation. Following each voluntary isotonic contraction (velocity range ~ 35°/s to ~ 275°/s), resting potentiated doublets were evaluated during passive joint rotation at the same angular velocity achieved during voluntary efforts, to account for force-velocity characteristics. Correlations between voluntary activation and the proportion of maximal torque or power were evaluated for isometric and isotonic contractions, respectively. RESULTS Isometric voluntary activation was strongly correlated with increasing torque output (r = 0.96, p < 0.001). Doublet torque during passive joint rotation displayed a hyperbolic relationship with increasing angular velocity (r = 0.98, p < 0.001). Isotonic voluntary activation was strongly correlated with increasing power output (r = 0.89, p < 0.001). During maximal effort contractions, no differences were observed in voluntary activation between isometric and isotonic conditions (89.4% vs. 89.2%, p = 0.904). CONCLUSIONS The ITT is a valid approach to evaluate voluntary activation during an isotonic contraction using a modified dynamometer. Participants were able to achieve a similar high level of voluntary activation during isometric and isotonic contractions.
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Affiliation(s)
- Michael T Paris
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada
- School of Kinesiology and Health Science, Faculty of Health, York University, Toronto, ON, Canada
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada.
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada.
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Dutra YM, Lopes JPF, Murias JM, Zagatto AM. Within- and between-day reliability and repeatability of neuromuscular function assessment in females and males. J Appl Physiol (1985) 2023; 135:1372-1383. [PMID: 37916269 DOI: 10.1152/japplphysiol.00539.2023] [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: 08/03/2023] [Revised: 10/31/2023] [Accepted: 10/31/2023] [Indexed: 11/03/2023] Open
Abstract
The study evaluated the reliability and repeatability of the force and surface electromyography activity (EMG) outcomes obtained through voluntary and electrically evoked contractions of knee extensors in females (n = 18) and males (n = 20) and compared these data between sexes. Maximal isometric voluntary contractions (iMVCs) of knee extensors associated with electrical stimulation of the femoral nerve were performed over 4 days (48-h interval), with the first day involving familiarization procedures, the second involving three trials (1-h interval), and the third and fourth involving just one trial. The intraclass correlation coefficient (ICC), coefficient of variation (CV), and repeatability of outcomes from within- and between-day trials were determined for each sex. Females presented lower maximal voluntary force during iMVC (iMVCForce) and associated vastus lateralis EMG activity (root mean square, RMSVL), force evoked by potentiated doublet high-frequency (Db100Force) and single stimuli (Qtw), and M-wave amplitude than males (P ≤ 0.01, partial eta squared ≥0.94). Voluntary activation (VA) and RMSVL/M-wave amplitude did not differ between sexes. iMVCForce, VA, Db100Force, Qtw, and M-wave amplitude were the most reliable outcomes in within-day trials, with similar results between sexes (ICC > 0.62; CV < 6.4%; repeatability: 12.2%-22.6%). When investigating between-day trials, the iMVCForce, VA, Db100Force, and Qtw were the most reliable (ICC > 0.66; CV < 7.5%; repeatability: 13.2%-33.45%) with similar results between sexes. In conclusion, females presented lower iMVCForce and evoked response than males. Although reliability and repeatability statistics vary between trials, data (e.g., from EMG or force signal), and sexes, most of the outcomes obtained through this technique are reliable in females and males.NEW & NOTEWORTHY Although reliability and repeatability of knee extensors vary according to the type of neuromuscular function outcome (e.g., from force or EMG responses), the trial intervals (i.e., hours or days), and the sex of the participant, most force and EMG outcomes obtained through these neuromuscular assessment protocols present ICC > 0.75, very good CV (<10%), and repeatability <25% in within- and between-day trials in both sexes.
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Affiliation(s)
- Yago Medeiros Dutra
- Department of Physical Education, Laboratory of Physiology and Sport Performance (LAFIDE), School of Sciences, São Paulo State University (UNESP), Bauru, Brazil
| | - João Pedro Fialho Lopes
- Department of Physical Education, Laboratory of Physiology and Sport Performance (LAFIDE), School of Sciences, São Paulo State University (UNESP), Bauru, Brazil
| | - Juan M Murias
- College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
| | - Alessandro Moura Zagatto
- Department of Physical Education, Laboratory of Physiology and Sport Performance (LAFIDE), School of Sciences, São Paulo State University (UNESP), Bauru, Brazil
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Gaemelke T, Jørgensen MLK, Riemenschneider M, Dalgas U, Hvid LG. The combined deleterious effects of multiple sclerosis and ageing on neuromuscular function. Exp Gerontol 2023; 184:112339. [PMID: 38029888 DOI: 10.1016/j.exger.2023.112339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/03/2023] [Accepted: 11/26/2023] [Indexed: 12/01/2023]
Abstract
BACKGROUND The prevalence of older (>60 years) people with multiple sclerosis (pwMS) is increasing. This introduces numerous challenges, as both MS and ageing independently contribute to the deterioration of neuromuscular function. AIM The aim was to compare the neuromuscular function in pwMS and healthy controls (HC) across three age groups: young, middle-aged, and old. METHODS Using a cross-sectional study design, the maximal muscle strength (Fmax) and rate of force development (RFD) of the knee extensors (KE) and plantar flexors (PF) were assessed using an isokinetic dynamometer. In addition, voluntary activation (VA) and resting twitch (RT) were measured using the interpolated twitch technique. RESULTS The Fmax, RFD, and VA of the KE were reduced in pwMS compared to HC across age groups. In pwMS, reductions were observed in PF Fmax, RFD, and RT, predominantly in the middle-aged and old age groups. Reductions increased with age in KE for both groups (except for VA) but in PF only for pwMS. The "trajectory" differed between pwMS and HC, as pwMS showed reductions from young to middle age, while HC showed reductions from middle to old age in KE. CONCLUSION The combined negative effects of MS and ageing on neuromuscular function were especially present in the PF but also substantial in the KE. RFD showed large deficits for pwMS compared to HC across age groups. The findings can partly be explained by a reduction in VA and RT, but further investigations of neural regulation are needed to explain large RFD deficits.
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Affiliation(s)
- Tobias Gaemelke
- Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark.
| | | | | | - Ulrik Dalgas
- Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark
| | - Lars G Hvid
- Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark; The Danish MS Hospitals, Ry and Haslev, Denmark
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Osborne JO, Tallent J, Girard O, Marshall PW, Kidgell D, Buhmann R. Neuromuscular electrical stimulation during maximal voluntary contraction: a Delphi survey with expert consensus. Eur J Appl Physiol 2023; 123:2203-2212. [PMID: 37247005 PMCID: PMC10492693 DOI: 10.1007/s00421-023-05232-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Accepted: 05/16/2023] [Indexed: 05/30/2023]
Abstract
PURPOSE The use of electrical stimulation to assess voluntary activation of muscle/s is a popular method employed in numerous exercise science and health research settings. This Delphi study aimed to collate expert opinion and provide recommendations for best practice when using electrical stimulation during maximal voluntary contractions. METHODS A two-round Delphi study was undertaken with 30 experts who completed a 62-item questionnaire (Round 1) comprising of open- and closed-ended questions. Consensus was assumed if ≥ 70% of experts selected the same response; such questions were removed from the subsequent Round 2 questionnaire. Responses were also removed if they failed to meet a 15% threshold. Open-ended questions were analysed and converted into closed-ended questions for Round 2. It was assumed there was no clear consensus if a question failed to achieve a ≥ 70% response in Round 2. RESULTS A total of 16 out of 62 (25.8%) items reached consensus. Experts agreed that electrical stimulation provides a valid assessment of voluntary activation in specific circumstances, such as during maximal contraction, and this stimulation can be applied at either the muscle or the nerve. Experts recommended using doublet stimuli, self-adhesive electrodes, a familiarisation session, real-time visual or verbal feedback during the contraction, a minimum current increase of + 20% to ensure supramaximal stimulation, and manually triggering stimuli. CONCLUSION The results of this Delphi consensus study can help researchers make informed decisions when considering technical parameters when designing studies involving electrical stimulation for the assessment of voluntary activation.
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Affiliation(s)
- J O Osborne
- School of Sport Sciences, UiT The Arctic University of Norway, Medisin- Og Helsebygget, UiT, 9037, Tromsø, Norway.
| | - J Tallent
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Colchester, UK
- Monash Exercise Neuroplasticity Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Melbourne, VA, Australia
| | - O Girard
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Perth, WA, Australia
| | - P W Marshall
- School of Health Sciences, Western Sydney University, Penrith, NSW, Australia
- Department of Exercise Science, University of Auckland, Auckland, New Zealand
| | - D Kidgell
- Monash Exercise Neuroplasticity Research Unit, Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Melbourne, VA, Australia
| | - R Buhmann
- School of Health and Behavioural Sciences, University of the Sunshine Coast, Maroochydore, QLD, Australia
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Carpenter RS, Samaan MA, Clasey JL, Butterfield TA, Gao F, Hardy PA, Bollinger LM. Association of vastus lateralis diffusion properties with in vivo quadriceps contractile function in premenopausal women. Scand J Med Sci Sports 2023; 33:213-223. [PMID: 36337008 PMCID: PMC9928607 DOI: 10.1111/sms.14266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 09/10/2022] [Accepted: 10/23/2022] [Indexed: 11/09/2022]
Abstract
BACKGROUND Diffusion tensor imaging (DTI) parameters correlate with muscle fiber composition, but it is unclear how these relate to in vivo contractile function. PURPOSE To determine the relationship between DTI parameters of the vastus lateralis (VL) and in vivo knee extensor contractile. METHODS Thirteen healthy, premenopausal women underwent magnetic resonance imaging of the mid-thigh to determine patellar tendon moment arm length and quadriceps cross-sectional area. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) of the VL were determined using diffusion tensor imaging (DTI). Participants underwent an interpolated twitch (ITT) experiment before and after a fatiguing concentric-eccentric isokinetic knee extension (60°·s-1 ). During the ITT, supramaximal electrical stimuli were delivered to elicit twitch responses from the knee extensors before, during, and after a maximal voluntary isometric contraction (MVIC). Knee extensor-specific tension during twitch and MVIC were calculated from isometric torque data. Pearson's correlations were used to determine the relationship between muscle contractile properties and DTI parameters. RESULTS MD and RD were moderately correlated with peak twitch force and rate of force development. FA and AD were moderately inversely related to percent change in MVIC following exercise. CONCLUSION MD and RD are associated with in vivo quadriceps twitch properties but not voluntary strength, which may reflect the mechanical properties of constituent fiber types. FA and AD appear to relate to MVIC strength following fatiguing exercise.
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Affiliation(s)
- Rebekah S Carpenter
- Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, Kentucky, USA
| | - Michael A Samaan
- Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, Kentucky, USA
| | - Jody L Clasey
- Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, Kentucky, USA
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA
- Body Composition Core Laboratory, University of Kentucky, Lexington, Kentucky, USA
| | - Tim A Butterfield
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA
- Department of Athletic Training, University of Kentucky, Lexington, Kentucky, USA
| | - Fan Gao
- Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, Kentucky, USA
| | - Peter A Hardy
- Department of Radiology, University of Kentucky, Lexington, Kentucky, USA
- Magnetic Resonance Imaging and Spectroscopy Center, University of Kentucky, Lexington, Kentucky, USA
| | - Lance M Bollinger
- Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, Kentucky, USA
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA
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Coratella G, Cè E, Doria C, Borrelli M, Toninelli N, Rampichini S, Limonta E, Longo S, Esposito F. Is the Interpolated-Twitch Technique-Derived Voluntary Activation Just Neural? Novel Perspectives from Mechanomyographic Data. Med Sci Sports Exerc 2023; 55:469-481. [PMID: 36288476 DOI: 10.1249/mss.0000000000003076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
PURPOSE Voluntary activation (VA) determined by interpolation-twitch technique could be affected by the characteristics of the in-series elastic components. To overcome this possible bias, a novel approach based on the mechanomyographic (MMG) signal to detect voluntary activation (VA MMG ) has been proposed. We examined the changes in VA and VA MMG after passive stretching to check the influence of neural and mechanical factors in the force output. METHODS Twenty-six healthy men underwent VA assessment using the interpolated-twitch technique before and after unilateral passive stretching of the plantarflexors (five 45-s on + 15-s off). In addition to the force signal, the MMG signal was detected on gastrocnemius medialis, gastrocnemius lateralis, and soleus. From the force and MMG signal analysis, VA and VA MMG were calculated in the stretched and contralateral nonstretched limbs. Joint passive stiffness was also defined. RESULTS In the stretched limb, passive stretching increased dorsiflexion range (mean ± SD = +18% ± 10%, P < 0.001, ES = 1.54) but reduced joint passive stiffness (-22% ± 8%, P < 0.001, ES = -1.75), maximum voluntary contraction (-15% ± 7%, P < 0.001, ES = -0.87), VA (-7% ± 3%, P < 0.001, ES = -2.32), and VA MMG (~-5% ± 2%, P < 0.001, ES = -1.26/-1.14). In the contralateral nonstretched limb, passive stretching increased dorsiflexion range (+10% ± 6%, P < 0.001, ES = 0.80) but reduced joint passive stiffness (-3% ± 2%, P = 0.041, ES = -0.27), maximum voluntary contraction (-4% ± 3%, P = 0.035, ES = -0.24), VA (-4% ± 2%, P < 0.001, ES = -1.77), and VA MMG (~- 2% ± 1%, P < 0.05, ES = -0.54/-0.46). The stretch-induced changes in VA correlated with VA MMG ( R ranging from 0.447 to 0.583 considering all muscles) and with joint passive stiffness (stretched limb: R = 0.503; contralateral nonstretched limb: R = 0.530). CONCLUSIONS VA output is overall influenced by both neural and mechanical factors, not distinguishable using the interpolated-twitch technique. VA MMG is a complementary index to assess the changes in VA not influenced by mechanical factors and to examine synergistic muscles.
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Affiliation(s)
- Giuseppe Coratella
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Milan, ITALY
| | | | - Christian Doria
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Milan, ITALY
| | - Marta Borrelli
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Milan, ITALY
| | - Nicholas Toninelli
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Milan, ITALY
| | - Susanna Rampichini
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Milan, ITALY
| | - Eloisa Limonta
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Milan, ITALY
| | - Stefano Longo
- Department of Biomedical Sciences for Health (SCIBIS), Università degli Studi di Milano, Milan, ITALY
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The effect of constant load cycling at extreme- and severe-intensity domains on performance fatigability and its determinants in young female. Sci Sports 2023. [DOI: 10.1016/j.scispo.2022.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Kotikangas J, Walker S, Toivonen S, Peltonen H, Häkkinen K. Acute Neuromuscular and Hormonal Responses to Power, Strength, and Hypertrophic Protocols and Training Background. Front Sports Act Living 2022; 4:919228. [PMID: 35911374 PMCID: PMC9329926 DOI: 10.3389/fspor.2022.919228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 06/01/2022] [Indexed: 11/20/2022] Open
Abstract
This study investigated how two slightly different athlete groups would differ in acute neuromuscular and endocrine responses to specific resistance exercise loadings and recovery compared to untrained participants. Power athletes (PA, n = 8), strength athletes (SA, n = 8) and non-athletes (NA, n = 7) performed power (PL, 7 × 6 × 50% of 1RM), maximal strength (MSL, 7 × 3 × 3RM), and hypertrophic (HL, 5 × 10 × 10RM) loadings in Smith-machine back-squat. Neuromuscular performance, serum testosterone, growth hormone, and cortisol concentrations, and blood lactate (BL) were measured before (Pre), at Mid and after (Post) loading, and after recovery for 24 and 48 h. All loadings led to acute decreases in neuromuscular performance and elevations in hormone concentrations and BL. During PL, a significant group × time interactions occurred in maximal isometric force [F(4, 40) = 4.189, p = 0.006, ηp2 = 0.295] indicating a greater decrease in PA compared to SA from Pre to Mid (p < 0.05), and in countermovement jump height [F(4, 40) = 2.895, p = 0.034, ηp2 = 0.224] indicating a greater decrease in NA compared to SA from Pre to Mid (p < 0.05). During HL, growth hormone was higher in Mid and Post in SA compared to NA (p < 0.05). No significant interactions were found during recovery. The differences during PL and HL suggest that the training background may enhance acute responses during the present loadings, whereas it seemed to have a limited effect on the recovery.
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Affiliation(s)
- Johanna Kotikangas
- Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
- *Correspondence: Johanna Kotikangas
| | - Simon Walker
- Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
- NeuroMuscular Research Center, Jyväskylä, Finland
| | - Sara Toivonen
- Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Heikki Peltonen
- Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
- NeuroMuscular Research Center, Jyväskylä, Finland
| | - Keijo Häkkinen
- Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
- NeuroMuscular Research Center, Jyväskylä, Finland
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9
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Cè E, Coratella G, Doria C, Borrelli M, Rampichini S, Limonta E, Longo S, Esposito F. Determining voluntary activation in synergistic muscles: a novel mechanomyographic approach. Eur J Appl Physiol 2022; 122:1897-1913. [PMID: 35610394 PMCID: PMC9287262 DOI: 10.1007/s00421-022-04966-8] [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: 12/27/2021] [Accepted: 05/02/2022] [Indexed: 11/30/2022]
Abstract
PURPOSE Drawing on correlations between the mechanomyographic (MMG) and the force signal, we devised a novel approach based on MMG signal analysis to detect voluntary activation (VA) of the synergistic superficial heads of the quadriceps muscle. We hypothesized that, after a fatiguing exercise, the changes in the evoked MMG signal of each quadriceps head would correlate with the changes in the level of VA in the whole quadriceps. METHODS Twenty-five men underwent a unilateral single-leg quadriceps exercise to failure. Before and after exercise, VA was assessed by interpolated-twitch-technique via nerve stimulation during and after maximum voluntary contraction (MVC). The force and MMG signal were recorded from vastus lateralis, vastus medialis, and rectus femoris. The MMG peak-to-peak was calculated and the voluntary activation index (VAMMG), defined as the superimposed/potentiated MMG peak-to-peak ratio, was determined from the MMG signal for each head. RESULTS VAMMG presented a very high intraclass correlation coefficient (0.981-0.998) and sensitivity (MDC95%: 0.42-6.97%). MVC and VA were decreased after exercise in both the exercising [MVC:-17(5)%, ES -0.92; VA: -7(3)%, ES -1.90] and the contralateral limb [MVC: -9(4)%, ES -0.48; VA: -4(1)%, ES -1.51]. VAMMG was decreased in both the exercising [~ -9(6)%, ES -1.77] and contralateral limb [~ -3(2)%, ES -0.57], with a greater decrease in VAMMG noted only in the vastus medialis of the exercising limb. Moderate-to-very high correlations were found between VAMMG and VA (R-range: 0.503-0.886) before and after exercise. CONCLUSION VAMMG may be implemented to assess VA and provide further information when multiple synergistic muscle heads are involved in fatiguing exercises.
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Affiliation(s)
- Emiliano Cè
- Department of Biomedical Sciences for Health (SCIBIS), Università Degli Studi Di Milano, University of Milan, Via Colombo 71, 20133, Milan, Italy. .,IRCSS Galeazzi Orthopedic Institute, Via Riccardo Galeazzi, 4, 20161, Milan, Italy.
| | - Giuseppe Coratella
- Department of Biomedical Sciences for Health (SCIBIS), Università Degli Studi Di Milano, University of Milan, Via Colombo 71, 20133, Milan, Italy
| | - Christian Doria
- Department of Biomedical Sciences for Health (SCIBIS), Università Degli Studi Di Milano, University of Milan, Via Colombo 71, 20133, Milan, Italy
| | - Marta Borrelli
- Department of Biomedical Sciences for Health (SCIBIS), Università Degli Studi Di Milano, University of Milan, Via Colombo 71, 20133, Milan, Italy
| | - Susanna Rampichini
- Department of Biomedical Sciences for Health (SCIBIS), Università Degli Studi Di Milano, University of Milan, Via Colombo 71, 20133, Milan, Italy
| | - Eloisa Limonta
- Department of Biomedical Sciences for Health (SCIBIS), Università Degli Studi Di Milano, University of Milan, Via Colombo 71, 20133, Milan, Italy
| | - Stefano Longo
- Department of Biomedical Sciences for Health (SCIBIS), Università Degli Studi Di Milano, University of Milan, Via Colombo 71, 20133, Milan, Italy
| | - Fabio Esposito
- Department of Biomedical Sciences for Health (SCIBIS), Università Degli Studi Di Milano, University of Milan, Via Colombo 71, 20133, Milan, Italy.,IRCSS Galeazzi Orthopedic Institute, Via Riccardo Galeazzi, 4, 20161, Milan, Italy
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WOODS STACEY, O’MAHONEY CARAGH, MAYNARD JAMES, DOTAN RAFFY, TENENBAUM GERSHON, FILHO EDSON, FALK BAREKET. Increase in Volitional Muscle Activation from Childhood to Adulthood: A Systematic Review and Meta-analysis. Med Sci Sports Exerc 2022; 54:789-799. [PMID: 34967802 PMCID: PMC9012528 DOI: 10.1249/mss.0000000000002853] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Children's maximal muscle strength is consistently lower than adults', even when normalized to body size. Lower volitional muscle activation (VA) in children is often considered one of the main reasons for age-related differences in muscular performance. However, some recent studies have reported similar VA in children and adults, bringing into question whether there is indeed an age-related increase in VA. The purpose of this review was to determine the effect of age on VA during maximal isometric contractions. METHODS Literature examining VA differences, using twitch interpolation in children (7-14 yr) and adults (16-28 yr), was systematically reviewed. Of the 1915 studies initially identified, 19 data sets were eligible for inclusion in the qualitative analysis and 14 in the quantitative meta-analysis (comprising 207 children and 193 adults). RESULTS Significantly lower VA in children was reported in 9/19 (47%) studies. A random-effects meta-analysis found a strong effect of age on VA, supporting lower VA in children compared with adults (Hedges' g = 1.55; confidence interval: 0.9-2.13). Moderator analysis included muscle group, sex, children's age, stimulation number (singlet, multiple), type (electric, magnetic), and location (muscle, nerve), of which only muscle group was significant (P < 0.001). A significant Egger's regression test and asymmetrical funnel plot suggest that publication bias may be present. CONCLUSIONS Overall, these findings suggest that compared with adults, children activate their motor-unit pool less compared with adults. Moreover, that the degree of VA increase with age may be influenced by the muscle examined (upper vs lower extremity). However, more research is needed to elucidate the influence of this possible factor, as the current review contains limited data from upper body muscles. The developmental mechanism responsible for children's lower VA requires further research.
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Affiliation(s)
- STACEY WOODS
- Department of Kinesiology, Brock University, St. Catharines, ON, CANADA
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, CANADA
| | - CARAGH O’MAHONEY
- Department of Kinesiology, Brock University, St. Catharines, ON, CANADA
| | - JAMES MAYNARD
- Department of Kinesiology, Brock University, St. Catharines, ON, CANADA
| | - RAFFY DOTAN
- Department of Kinesiology, Brock University, St. Catharines, ON, CANADA
| | - GERSHON TENENBAUM
- B. Ivcher School of Psychology, Reichman University, Herzliya, ISRAEL
| | - EDSON FILHO
- Wheelock College of Education and Human Development, Boston University, Boston, MA
| | - BAREKET FALK
- Department of Kinesiology, Brock University, St. Catharines, ON, CANADA
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, CANADA
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11
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Pérez Olivera AL, Solan MC, Karamanidis K, Mileva KN, James DC. A voluntary activation deficit in m. abductor hallucis exists in asymptomatic feet. J Biomech 2021; 130:110863. [PMID: 34844033 DOI: 10.1016/j.jbiomech.2021.110863] [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] [Received: 02/24/2021] [Revised: 11/07/2021] [Accepted: 11/08/2021] [Indexed: 01/06/2023]
Abstract
M. abductor hallucis (AbH) is the strongest intrinsic foot muscle and its dysfunction underlies various foot disorders. Attempts to strengthen the muscle by voluntary exercises are constrained by its complex morphology and oblique mechanical action, which leads to an inability even in asymptomatic individuals to fully activate AbH. This study investigated the extent and magnitude of this inability whilst also providing preliminary evidence for the virtue of targeted sub-maximum neuromuscular electrical stimulation (NMES) as a countermeasure for an AbH activation deficit. The voluntary activation ratio (VAR) was assessed via the twitch interpolation technique in the left AbH of 13 healthy participants during maximum voluntary 1st metatarsophalangeal joint flexion-abduction contractions (MVC). Participants were grouped ("able" or "unable") based on their ability to fully activate AbH (VAR ≥ 0.9). 7 s-NMES trains (20 Hz) were then delivered to AbH with current intensity increasing from 150% to 300% motor threshold (MT) in 25% increments. Perceived comfort was recorded (10 cm-visual analogue scale; VAS). Only 3 participants were able to activate AbH to its full capacity (able, mean (range) VAR: 0.93 (0.91-0.95), n = 3; unable: 0.69 (0.36-0.83), n = 10). However, the maximum absolute forces produced during the graded sub-maximum direct-muscle NMES protocol were comparable between groups implying that the peripheral contractility of AbH is intact irrespective of the inability of individuals to voluntary activate AbH to its full capacity. These findings demonstrate that direct-muscle NMES overcomes the prevailing inability for high voluntary AbH activation and therefore offers the potential to strengthen the healthy foot and restore function in the pathological foot.
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Affiliation(s)
- Andrei L Pérez Olivera
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, UK.
| | - Matthew C Solan
- Department of Trauma and Orthopaedic Surgery, Royal Surrey County Hospital, Guildford, Surrey GU2 5XX, UK
| | - Kiros Karamanidis
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, UK
| | - Katya N Mileva
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, UK
| | - Darren C James
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, UK
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12
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Gaemelke T, Riemenschneider M, Dalgas U, Kjølhede T, Rasmussen C, Stenager E, Overgaard K, Hvid LG. Comparison Between Isometric and Concentric Motor Fatigability in Persons With Multiple Sclerosis and Healthy Controls - exploring central and peripheral contributions of motor fatigability. Neurorehabil Neural Repair 2021; 35:644-653. [PMID: 34027727 DOI: 10.1177/15459683211017502] [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: 12/12/2022]
Abstract
BACKGROUND Motor fatigability (i.e. contraction-induced reduction in muscle strength) from a concentric task associate stronger to walking and perception of fatigue in persons with multiple sclerosis (pwMS), compared with an isometric task. However, the central and peripheral contributions of motor fatigability between these tasks have not been investigated. OBJECTIVE Compare the central and peripheral contributions of motor fatigability in the knee extensors in a sustained isometric fatigability protocol versus a concentric fatigability protocol and in pwMS versus healthy controls (HCs). METHODS Participants (n=31 pwMS; n=15 HCs) underwent neuromuscular testing before and immediately after two knee extensor fatigability tasks (sustained isometric and concentric) in an isokinetic dynamometer. Neuromuscular testing of fatigability consisted of maximal voluntary contraction, voluntary activation (central/neural contributor), and resting twitch (peripheral/muscular contributor) determined by the interpolated twitch technique. RESULTS Sustained isometric and concentric fatigability protocols resulted in motor fatigability for both pwMS and HCs, with no between-protocols differences for either group. Regression analysis showed that motor fatigability variance in pwMS was mainly attributed to central fatigability in the sustained isometric protocol and to both central and peripheral fatigability in the concentric protocol. In HCs, the variance in sustained isometric and concentric fatigability were attributed to both peripheral and central fatigability. CONCLUSION Central and peripheral contributions of motor fatigability differed between sustained isometric and concentric protocols as well as between pwMS and HCs. These between-protocol differences in pwMS provide a neuromuscular dimension to the reported difference in the strength of associations of concentric and isometric tasks to walking and perception of fatigue in pwMS.
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Affiliation(s)
| | | | | | - Tue Kjølhede
- Aarhus University, Denmark.,Odense University Hospital, Denmark
| | | | - Egon Stenager
- University of Southern Denmark, Odense, Denmark.,MS-Clinic of Southern Jutland (Sønderborg, Esbjerg, Kolding), Sønderborg, Denmark
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13
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Quantification of central fatigue: a central debate. Eur J Appl Physiol 2021; 121:2375-2376. [PMID: 33991239 DOI: 10.1007/s00421-021-04713-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 05/05/2021] [Indexed: 10/21/2022]
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14
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Dotan R, Woods S, Contessa P. On the reliability and validity of central fatigue determination. Eur J Appl Physiol 2021; 121:2393-2411. [PMID: 33966110 DOI: 10.1007/s00421-021-04700-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 04/24/2021] [Indexed: 11/30/2022]
Abstract
Physical performance fatigue can be ascribed to both peripheral and central components. Central fatigue, however, is an elusive entity, consisting of cognitive/sensory component and presumably also a neuro-physiological component that are difficult to tease apart and assess independently of each other. The most widely accepted method for the assessment of central fatigue is based on the premise that decreasing volitional muscle activation (VA), as determined by the interpolated twitch technique (ITT) in fatiguing muscles, reflects increasing central fatigue. Suffering its own shortcomings, the validity of VA determination under fatigued conditions has never been proven and is only assumed. This review presents evidence that questions ITT's reliability and validity in reflecting VA in the fatiguing muscle and, consequently, VA's validity for central fatigue assessment. Specifically highlighted is the paradox of children and endurance athletes, who share striking endurance characteristics, being claimed as more centrally fatigable than untrained adults. Further research and new directions are needed for confirming and quantifying central fatigue and teasing apart its psychologic and neuromotor components.
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Affiliation(s)
- Raffy Dotan
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St Catharines, ON, Canada.
| | - Stacey Woods
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St Catharines, ON, Canada
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15
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Abstract
Neuromuscular fatigue (NMF) is usually assessed non-invasively in healthy, athletic or clinical populations with the combination of voluntary and evoked contractions. Although it might appear relatively straightforward to magnetically or electrically stimulate at different levels (cortical/spinal/muscle) and to measure mechanical and electromyographic responses to quantify neuromuscular adjustments due to sustained/repeated muscle contractions, there are drawbacks that researchers and clinicians need to bear in mind. The aim of this opinion paper is to highlight the pitfalls inevitably faced when NMF is quantified. The first problem might arise from the definition of fatigue itself and the parameter(s) used to measure it; for instance, measuring power vs. isometric torque may lead to different conclusions. Another potential limitation is the delay between exercise termination and the evaluation of neuromuscular function; the possible underestimation of exercise-induced neural and contractile impairment and misinterpretation of fatigue etiology will be discussed, as well as solutions recently proposed to overcome this problem. Quantification of NMF can also be biased (or not feasible) because of the techniques themselves (e.g. results may depend on stimulation intensity for transcranial magnetic stimulation) or the way data are analyzed (e.g. M wave peak-to-peak vs first phase amplitude). When available, alternatives recently suggested in the literature to overcome these pitfalls are considered and recommendations about the best practices to assess NMF (e.g. paying attention to the delay between exercise and testing, adapting the method to the characteristics of the population to be tested and considering the limitations associated with the techniques) are proposed.
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Affiliation(s)
- Nicolas Place
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Guillaume Y Millet
- Univ Lyon, UJM-Saint-Etienne, Inter-University Laboratory of Human Movement Biology, EA 7424, 42023, Saint-Étienne, France. .,Faculty of Kinesiology, University of Calgary, Calgary, Canada.
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16
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Olsen S, Signal N, Niazi IK, Rashid U, Alder G, Mawston G, Nedergaard RB, Jochumsen M, Taylor D. Peripheral Electrical Stimulation Paired With Movement-Related Cortical Potentials Improves Isometric Muscle Strength and Voluntary Activation Following Stroke. Front Hum Neurosci 2020; 14:156. [PMID: 32499686 PMCID: PMC7242792 DOI: 10.3389/fnhum.2020.00156] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 04/09/2020] [Indexed: 12/18/2022] Open
Abstract
Background Endogenous paired associative stimulation (ePAS) is a neuromodulatory intervention that has potential to aid stroke recovery. ePAS involves pairing endogenous electroencephalography (EEG) signals known as movement-related cortical potentials (MRCPs), with peripheral electrical stimulation. Previous studies have used transcranial magnetic stimulation (TMS) to demonstrate changes in corticomotor excitability following ePAS. However, the use of TMS as a measure in stroke research is limited by safety precautions, intolerance, and difficulty generating a measurable response in more severely affected individuals. We were interested in evaluating the effect of ePAS using more feasible measures in people with stroke. This study asks whether ePAS produces immediate improvements in the primary outcomes of maximal voluntary isometric contraction (MVIC) and total neuromuscular fatigue of the dorsiflexor muscles, and in the secondary outcomes of muscle power, voluntary activation (VA), central fatigue, peripheral fatigue, and electromyography activity. Method In this repeated-measures cross-over study, 15 participants with chronic stroke completed two interventions, ePAS and sham, in a randomized order. During ePAS, 50 repetitions of visually cued dorsiflexion were completed, while single pulses of electrical stimulation were delivered to the deep branch of the common peroneal nerve. Each somatosensory volley was timed to arrive in the primary motor cortex at the peak negativity of the MRCP. Univariate and multivariate linear mixed models were used to analyze the primary and secondary data, respectively. Results There was a statistically significant increase in dorsiflexor MVIC immediately following the ePAS intervention (mean increase 7 N), compared to the sham intervention (mean change 0 N) (univariate between-condition analysis p = 0.047). The multivariate analysis revealed a statistically significant effect of ePAS on VA of the tibialis anterior muscle, such that ePAS increased VA by 7 percentage units (95% confidence interval 1.3–12.7%). There was no statistically significant effect on total neuromuscular fatigue, muscle power, or other secondary measures. Conclusion A single session of ePAS can significantly increase isometric muscle strength and VA in people with chronic stroke. The findings confirm that ePAS has a central neuromodulatory mechanism and support further exploration of its potential as an adjunct to stroke rehabilitation. In addition, the findings offer alternative, feasible outcome measures for future research. Clinical trial registration Australia New Zealand Clinical Trials Registry ACTRN12617000838314 (www.anzctr.org.au), Universal Trial Number U111111953714.
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Affiliation(s)
- Sharon Olsen
- Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand
| | - Nada Signal
- Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand
| | - Imran K Niazi
- Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand.,Centre for Chiropractic Research, New Zealand College of Chiropractic, Auckland, New Zealand.,Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Usman Rashid
- Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand
| | - Gemma Alder
- Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand
| | - Grant Mawston
- Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand
| | - Rasmus B Nedergaard
- Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.,Mech-Sense, Department of Gastroenterology and Hepatology, Aalborg University Hospital, Aalborg, Denmark
| | - Mads Jochumsen
- Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Denise Taylor
- Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand
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17
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Alexander AM, Didier KD, Hammer SM, Dzewaltowski AC, Kriss KN, Lovoy GM, Hammer JL, Smith JR, Ade CJ, Broxterman RM, Barstow TJ. Exercise tolerance through severe and extreme intensity domains. Physiol Rep 2020; 7:e14014. [PMID: 30825269 PMCID: PMC6397101 DOI: 10.14814/phy2.14014] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 02/01/2019] [Indexed: 01/24/2023] Open
Abstract
The power‐duration relationship accurately predicts exercise tolerance for constant power exercise performed in the severe intensity domain. However, the accuracy of the prediction of time to task failure (Tlim) is currently unclear for work rates (WR) above severe intensities; that is, within the extreme intensity domain (Tlim < 2 min). We hypothesized that Tlim would be shorter for WRs within the extreme intensity domain than predicted from the linear 1/time relationship of the severe intensity domain which would suggest mechanisms limiting exercise are different between intensity domains. Six men completed 7 knee‐extension tests. Tlim of extreme intensity exercise (60%, 70%, 80%, and 90% 1RM; Tlim < 2 min) were compared to the predicted Tlim from the slope of the S1–S3 (Tlim ≥ 2–15 min) regression. Twitch force (Qtw) and maximal voluntary contraction (MVC) were measured on the right vastus lateralis before and after each test. Tlim at 70–90% 1RM were shorter than the Tlim predicted by the severe domain 1/time model (P < 0.05); however, Tlim at 60% 1RM was not different than the predicted severe Tlim, suggesting the mechanisms limiting extreme exercise manifest ≥60% 1RM. A significant linear relationship for 60–90% 1RM was observed which suggested a curvature constant unique to the extreme domain (Wext′) that was smaller than the W ′ of the severe domain (1.5 ± 0.6 vs. 5.9 ± 1.5 kJ, P < 0.001). Qtw and MVC were significantly decreased following severe exercise, however, Qtw and MVC were not significantly decreased following 80% and 90% 1RM, giving evidence that mechanisms causing task failure were recovered by the time post‐exercise measurements were made (~90 sec).
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Affiliation(s)
| | - Kaylin D Didier
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Shane M Hammer
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | | | - Karly N Kriss
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Garrett M Lovoy
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Joseph L Hammer
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Joshua R Smith
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Carl J Ade
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Ryan M Broxterman
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Thomas J Barstow
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
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18
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Alexandre F, Héraud N, Tremey E, Oliver N, Bourgouin D, Varray A. Specific motor cortex hypoexcitability and hypoactivation in COPD patients with peripheral muscle weakness. BMC Pulm Med 2020; 20:1. [PMID: 31900129 PMCID: PMC6942311 DOI: 10.1186/s12890-019-1042-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 12/24/2019] [Indexed: 12/05/2022] Open
Abstract
Background Peripheral muscle weakness can be caused by both peripheral muscle and neural alterations. Although peripheral alterations cannot totally explain peripheral muscle weakness in COPD, the existence of an activation deficit remains controversial. The heterogeneity of muscle weakness (between 32 and 57% of COPD patients) is generally not controlled in studies and could explain this discrepancy. This study aimed to specifically compare voluntary and stimulated activation levels in COPD patients with and without muscle weakness. Methods Twenty-two patients with quadriceps weakness (COPDMW), 18 patients with preserved quadriceps strength (COPDNoMW) and 20 controls were recruited. Voluntary activation was measured through peripheral nerve (VAperipheral) and transcranial magnetic (VAcortical) stimulation. Corticospinal and spinal excitability (MEP/Mmax and Hmax/Mmax) and corticospinal inhibition (silent period duration) were assessed during maximal voluntary quadriceps contractions. Results COPDMW exhibited lower VAcortical and lower MEP/Mmax compared with COPDNoMW (p < 0.05). Hmax/Mmax was not significantly different between groups (p = 0.25). Silent period duration was longer in the two groups of COPD patients compared with controls (p < 0.01). Interestingly, there were no significant differences between all COPD patients taken together and controls regarding VAcortical and MEP/Mmax. Conclusions COPD patients with muscle weakness have reduced voluntary activation without altered spinal excitability. Corticospinal inhibition is higher in COPD regardless of muscle weakness. Therefore, reduced cortical excitability and a voluntary activation deficit from the motor cortex are the most likely cortical mechanisms implicated in COPD muscle weakness. The mechanisms responsible for cortical impairment and possible therapeutic interventions need to be addressed.
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Affiliation(s)
- Francois Alexandre
- Les Cliniques du Souffle, Research Department, Groupe 5 Santé, 800 avenue Joseph Vallot, 34700, Lodève, France. .,Euromov Laboratory, University of Montpellier, Montpellier, France.
| | - Nelly Héraud
- Les Cliniques du Souffle, Research Department, Groupe 5 Santé, 800 avenue Joseph Vallot, 34700, Lodève, France
| | - Emilie Tremey
- Les Cliniques du Souffle, Research Department, Groupe 5 Santé, 800 avenue Joseph Vallot, 34700, Lodève, France
| | - Nicolas Oliver
- Les Cliniques du Souffle, Research Department, Groupe 5 Santé, 800 avenue Joseph Vallot, 34700, Lodève, France
| | - Dominique Bourgouin
- Les Cliniques du Souffle, Research Department, Groupe 5 Santé, 800 avenue Joseph Vallot, 34700, Lodève, France
| | - Alain Varray
- Euromov Laboratory, University of Montpellier, Montpellier, France
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19
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Garmirian LRP, Acosta AM, Hill NM, Dewald JPA. Estimating Voluntary Activation Of The Elbow And Wrist Muscles In Chronic Hemiparetic Stroke Using Twitch Interpolation Methodology. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2019; 2018:2244-2247. [PMID: 30440852 DOI: 10.1109/embc.2018.8512791] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
One of the cardinal motor deficits that occurs after stroke is paresis, a decrease in the voluntary activation of muscles. Paresis leads to a decrease in voluntary joint strength, impacting stroke survivors' ability to perform activities of daily living (ADLs). Quantifying this decrease in voluntary activation is important when designing rehabilitation interventions to address movement impairments and restore the ability to perform ADLs. Twitch interpolation is an experimental technique developed to quantify muscle voluntary activation [1]. This method has been used widely across pathologies but often limited to assessment of the voluntary activation of the plantar flexors, given the ease of activating these muscles through stimulation of the tibial nerve [2]. The complex innervation of elbow and wrist musculature imposes practical difficulties when applying the twitch interpolation technique to these joints [1]. Therefore, only a few studies have used this technique to examine the pathological [3]-[5] upper extremity, with little quantitative data documenting the degree of paresis present in the upper limb after stroke. The goal of this study is to evaluate the feasibility of applying twitch interpolation to quantify voluntary activation of the elbow and wrist flexors and extensors in chronic stroke survivors.
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20
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Kirk BJC, Trajano GS, Pulverenti TS, Rowe G, Blazevich AJ. Neuromuscular Factors Contributing to Reductions in Muscle Force After Repeated, High-Intensity Muscular Efforts. Front Physiol 2019; 10:783. [PMID: 31293449 PMCID: PMC6601466 DOI: 10.3389/fphys.2019.00783] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/04/2019] [Indexed: 01/07/2023] Open
Abstract
Multiple neuromuscular processes contribute to the loss of force production following repeated, high-intensity muscular efforts; however, the relative contribution of each process is unclear. In Experiment 1, 16 resistance trained men performed six sets of unilateral isometric plantar flexor contractions of the right leg (3 s contraction/2 s rest; 85% maximal voluntary contraction torque; 90-s inter-set rest) until failure with and without caffeine ingestion (3 mg kg-1) on two separate days. Corticospinal excitability and cortical silent period (cSP) were assessed before and immediately, 10 and 20 min after the exercise. In Experiment 2, electrically evoked tetanic force and persistent inward current (PIC)-mediated facilitation of the motor neuron pool (estimated using neuromuscular electrical stimulation with tendon vibration) were assessed before and after the same exercise intervention in 17 resistance trained men. Results showed decreases in peak plantar flexion torque (Experiment 1: -12.2%, Experiment 2: -16.9%), electrically evoked torque (20 Hz -15.3%, 80 Hz -15.3%, variable-frequency train -17.9%), and cSP (-3.8%; i.e., reduced inhibition) post-exercise which did not recover by 20 min. Electromyographic activity (EMG; -6%), corticospinal excitability (-9%), and PIC facilitation (-24.8%) were also reduced post-exercise but recovered by 10 min. Caffeine ingestion increased torque and EMG but did not notably affect corticospinal excitability, PIC amplification, or electrically evoked torque. The data indicate that a decrease in muscle function largely underpins the loss of force after repeated, high-intensity muscular efforts, but that the loss is exacerbated immediately after the exercise by simultaneous decreases in corticospinal excitability and PIC amplitudes at the motor neurons.
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Affiliation(s)
- Benjamin J C Kirk
- Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Gabriel S Trajano
- School of Exercise and Nutrition Sciences, Faculty of Health and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Timothy S Pulverenti
- Department of Physical Therapy, College of Staten Island, Staten Island, NY, United States
| | - Grant Rowe
- Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Anthony J Blazevich
- Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
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21
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Improving the measurement of TMS-assessed voluntary activation in the knee extensors. PLoS One 2019; 14:e0216981. [PMID: 31170180 PMCID: PMC6553714 DOI: 10.1371/journal.pone.0216981] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 05/02/2019] [Indexed: 01/25/2023] Open
Abstract
PURPOSE To test the accuracy, validity, reliability and sensitivity of an alternative method for the measure of TMS-assessed voluntary activation (VATMS) in the knee extensors. METHODS Ten healthy males (24 ± 5 years) completed a neuromuscular assessment protocol before and after a fatiguing isometric exercise: two sets of five contractions (50%, 62.5%, 75%, 87.5%, 100% Maximal Voluntary Contraction; MVC) with superimposed TMS-evoked twitches for calculation of VATMS using either the first 5 stimulations (1x5C) or all 10 (2x5C). This was performed on two separate occasions (between-day reliability). Accuracy and validity were compared with a routinely used protocol [i.e. 50%, 75%, and 100% of MVC (1x3C) performed three times (3x3C)]. RESULTS 95% confidence interval for estimated resting twitch, a key determinant of VATMS, was similar between 1x5C, 2x5C, and 3x3C but improved by six-fold when compared to 1x3C (P<0.05). In a fresh state, potentiated twitch force was unchanged following 1x5C but decreased following 2x5C (P<0.05). A recovery was found post-exercise but was smaller for 1x5C compared to 2x5C (P<0.05), with no difference between the latter two (P>0.05). Absolute reliability was strong enough for both 1x5C and 2x5C to depict a true detectable change in the sample's VATMS following the fatiguing exercise (TEM < 3% at rest, <9% post-exercise) but 2x5C was marginally more sensitive to individual's changes from baseline. CONCLUSION Both 1x5C and 2x5C provide reliable measures of VATMS. However, 1x5C may hold stronger internal validity. Both protocols allow detection of 'true' changes in sample's means but not individual scores following a fatiguing isometric exercise.
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22
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Yacyshyn AF, Nettleton J, McNeil CJ. The Effects of Sex and Motoneuron Pool on Central Fatigue. Med Sci Sports Exerc 2019; 50:1061-1069. [PMID: 29283935 DOI: 10.1249/mss.0000000000001536] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
PURPOSE It is uncertain if sex influences central fatigue because the reduction in voluntary activation (VA) has been reported as not different between the sexes for elbow flexors (EF) but greater in males compared with females for knee extensors. This disparity could result from the facilitatory and inhibitory effects of group III/IV muscle afferents on flexor versus extensor motoneurons, respectively. The purpose of this study was to examine central fatigue and motoneuron responsiveness of EF and elbow extensors (EE) in males and females. METHODS Twenty-two participants (11 females) performed a 2-min isometric maximal voluntary contraction of EF and EE (on separate days) followed by 2 min of recovery. EMG potentials were recorded from biceps or triceps brachii in response to the stimulation of the brachial plexus (Mmax), corticospinal tract (cervicomedullary motor evoked potential [CMEP]), and motor cortex (motor evoked potential [MEP]). Superimposed and resting doublets (for determining VA) were evoked via muscle belly stimulation of biceps or triceps brachii. Only CMEP and superimposed doublets were recorded during fatigue. RESULTS There was no effect of sex on CMEP area for either muscle group during fatigue or recovery. During the 2 min after EE fatigue, mean normalized CMEP and MEP area were ∼85% and ∼141% of control, indicating inhibition and facilitation of the motoneurons and motor cortex, respectively. VA during recovery was significantly reduced in males but not females for the EF, and unchanged in either sex for the EE. CONCLUSION The findings do not support the concept that equivocal findings regarding sex differences in central fatigue are related to augmented effects of group III/IV afferent feedback in males compared with females.
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Affiliation(s)
- Alexandra F Yacyshyn
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, CANADA.,School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, CANADA
| | - Jane Nettleton
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, CANADA
| | - Chris J McNeil
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, CANADA.,School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, CANADA
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23
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Millet GY, Martin V, Temesi J. The role of the nervous system in neuromuscular fatigue induced by ultra-endurance exercise. Appl Physiol Nutr Metab 2018; 43:1151-1157. [DOI: 10.1139/apnm-2018-0161] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Ultra-endurance events are not a recent development but they have only become very popular in the last 2 decades, particularly ultramarathons run on trails. The present paper reviews the role of the central nervous system in neuromuscular fatigue induced by ultra-endurance exercise. Large decreases in voluntary activation are systematically found in ultra-endurance running but are attenuated in ultra-endurance cycling for comparable intensity and duration. This indirectly suggests that afferent feedback, rather than neurobiological changes within the central nervous system, is determinant in the amount of central fatigue produced. Whether this is due to inhibition from type III and IV afferent fibres induced by inflammation, disfacilitation of Ia afferent fibers owing to repeated muscle stretching or other mechanisms still needs to be determined. Sleep deprivation per se does not seem to play a significant role in central fatigue although it still affects performance by elevating ratings of perceived exertion. The kinetics of central fatigue and recovery, the influence of muscle group (knee extensors vs plantar flexors) on central deficit as well as the limitations related to studies on central fatigue in ultra-endurance exercise are also discussed in the present article. To date, no study has quantified the contribution of spinal modulations to central fatigue in ultra-endurance events. Future investigations utilizing spinal stimulation (i.e., thoracic stimulation) must be conducted to assess the role of changes in motoneuronal excitability on the observed central fatigue. Recovery after ultra-endurance events and the effect of sex on neuromuscular fatigue must also be studied further.
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Affiliation(s)
- Guillaume Y. Millet
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
| | - Vincent Martin
- Université Clermont Auvergne, AME2P, F-63000 Clermont-Ferrand, France
| | - John Temesi
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
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Abstract
It is well known that prolonged passive muscle stretch reduces maximal muscle force production. There is a growing body of evidence suggesting that adaptations occurring within the nervous system play a major role in this stretch-induced force reduction. This article reviews the existing literature, and some new evidence, regarding acute neurophysiological changes in response to passive muscle stretching. We discuss the possible contribution of supra-spinal and spinal structures to the force reduction after passive muscle stretch. In summary, based on the recent evidence reviewed we propose a new hypothesis that a disfacilitation occurring at the motoneuronal level after passive muscle stretch is a major factor affecting the neural efferent drive to the muscle and, subsequently, its ability to produce maximal force.
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Hvid LG, Aagaard P, Ørtenblad N, Kjaer M, Suetta C. Plasticity in central neural drive with short-term disuse and recovery - effects on muscle strength and influence of aging. Exp Gerontol 2018; 106:145-153. [PMID: 29476804 DOI: 10.1016/j.exger.2018.02.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 02/17/2018] [Accepted: 02/19/2018] [Indexed: 11/17/2022]
Abstract
While short-term disuse negatively affects mechanical muscle function (e.g. isometric muscle strength) little is known of the relative contribution of adaptions in central neural drive and peripheral muscle contractility. The present study investigated the relative contribution of adaptations in central neural drive and peripheral muscle contractility on changes in isometric muscle strength following short-term unilateral disuse (4 days, knee brace) and subsequent active recovery (7 days, one session of resistance training) in young (n = 11, 24 yrs) and old healthy men (n = 11, 67 yrs). Maximal isometric knee extensor strength (MVC) (isokinetic dynamometer), voluntary muscle activation (superimposed twitch technique), and electrically evoked muscle twitch force (single and doublet twitch stimulation) were assessed prior to and after disuse, and after recovery. Following disuse, relative decreases in MVC did not differ statistically between old (16.4 ± 3.7%, p < 0.05) and young (-9.7 ± 2.9%, p < 0.05) (mean ± SE), whereas voluntary muscle activation decreased more (p < 0.05) in old (-8.4 ± 3.5%, p < 0.05) compared to young (-1.1 ± 1.0%, ns) as did peak single (-25.8 ± 6.6%, p < 0.05 vs -7.6 ± 3.3%, p < 0.05) and doublet twitch force (-23.2 ± 5.5%, p < 0.05 vs -2.0 ± 2.6%, ns). All parameters were restored in young following 7 days recovery, whereas MVC and peak twitch force remained suppressed in old. Regression analysis revealed that disuse-induced changes in MVC relied more on changes in single twitch force in young (p < 0.05) and more on changes in voluntary muscle activation in old (p < 0.05), whereas recovery-induced changes in MVC mainly were explained by gains in voluntary muscle activation in both young and old. Altogether, the present data demonstrate that plasticity in voluntary muscle activation (~central neural drive) is a dominant mechanism affecting short-term disuse- and recovery-induced changes in muscle strength in older adults.
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Affiliation(s)
- Lars G Hvid
- Section for Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark.
| | - Per Aagaard
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark (SDU), Denmark
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark (SDU), Denmark; Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Sweden
| | - Michael Kjaer
- Bispebjerg Hospital, Institute of Sports Medicine and Center of Healthy Aging, University of Copenhagen, Denmark
| | - Charlotte Suetta
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet Glostrup, University of Copenhagen, Denmark
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Peterson CL, Bednar MS, Bryden AM, Keith MW, Perreault EJ, Murray WM. Voluntary activation of biceps-to-triceps and deltoid-to-triceps transfers in quadriplegia. PLoS One 2017; 12:e0171141. [PMID: 28253262 PMCID: PMC5333805 DOI: 10.1371/journal.pone.0171141] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 01/14/2017] [Indexed: 11/18/2022] Open
Abstract
The biceps or the posterior deltoid can be transferred to improve elbow extension function for many individuals with C5 or C6 quadriplegia. Maximum strength after elbow reconstruction is variable; the patient’s ability to voluntarily activate the transferred muscle to extend the elbow may contribute to the variability. We compared voluntary activation during maximum isometric elbow extension following biceps transfer (n = 5) and deltoid transfer (n = 6) in three functional postures. Voluntary activation was computed as the elbow extension moment generated during maximum voluntary effort divided by the moment generated with full activation, which was estimated via electrical stimulation. Voluntary activation was on average 96% after biceps transfer and not affected by posture. Individuals with deltoid transfer demonstrated deficits in voluntary activation, which differed by posture (80% in horizontal plane, 69% in overhead reach, and 70% in weight-relief), suggesting inadequate motor re-education after deltoid transfer. Overall, individuals with a biceps transfer better activated their transferred muscle than those with a deltoid transfer. This difference in neural control augmented the greater force-generating capacity of the biceps leading to increased elbow extension strength after biceps transfer (average 9.37 N-m across postures) relative to deltoid transfer (average 2.76 N-m across postures) in our study cohort.
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Affiliation(s)
- Carrie L. Peterson
- Edward Hines, Jr. VA Hospital, Hines, IL, United States of America
- Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, United States of America
- Department of Physical Medicine & Rehabilitation Northwestern University Feinberg School of Medicine, Chicago, IL, United States of America
- * E-mail:
| | - Michael S. Bednar
- Edward Hines, Jr. VA Hospital, Hines, IL, United States of America
- Department of Orthopaedic Surgery and Rehabilitation, Stritch School of Medicine, Loyola University Maywood, IL, United States of America
| | - Anne M. Bryden
- The Cleveland FES Center at MetroHealth, Cleveland, OH, United States of America
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States of America
| | - Michael W. Keith
- The Cleveland FES Center at MetroHealth, Cleveland, OH, United States of America
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States of America
- Department of Orthopaedics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States of America
| | - Eric J. Perreault
- Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, United States of America
- Department of Physical Medicine & Rehabilitation Northwestern University Feinberg School of Medicine, Chicago, IL, United States of America
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America
| | - Wendy M. Murray
- Edward Hines, Jr. VA Hospital, Hines, IL, United States of America
- Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, United States of America
- Department of Physical Medicine & Rehabilitation Northwestern University Feinberg School of Medicine, Chicago, IL, United States of America
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America
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Hvid LG, Strotmeyer ES, Skjødt M, Magnussen LV, Andersen M, Caserotti P. Voluntary muscle activation improves with power training and is associated with changes in gait speed in mobility-limited older adults — A randomized controlled trial. Exp Gerontol 2016; 80:51-6. [DOI: 10.1016/j.exger.2016.03.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 02/22/2016] [Accepted: 03/29/2016] [Indexed: 11/24/2022]
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Neyroud D, Cheng AJ, Bourdillon N, Kayser B, Place N, Westerblad H. Muscle Fatigue Affects the Interpolated Twitch Technique When Assessed Using Electrically-Induced Contractions in Human and Rat Muscles. Front Physiol 2016; 7:252. [PMID: 27445844 PMCID: PMC4924481 DOI: 10.3389/fphys.2016.00252] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 06/10/2016] [Indexed: 11/13/2022] Open
Abstract
The interpolated twitch technique (ITT) is the gold standard to assess voluntary activation and central fatigue. Yet, its validity has been questioned. Here we studied how peripheral fatigue can affect the ITT. Repeated contractions at submaximal frequencies were produced by supramaximal electrical stimulations of the human adductor pollicis muscle in vivo and of isolated rat soleus fiber bundles; an extra stimulation pulse was given during contractions to induce a superimposed twitch. Human muscles fatigued by repeated 30-Hz stimulation trains (3 s on–1 s off) showed an ~80% reduction in the superimposed twitch force accompanied by a severely reduced EMG response (M-wave amplitude), which implies action potential failure. Subsequent experiments combined a less intense stimulation protocol (1.5 s on–3 s off) with ischemia to cause muscle fatigue, but which preserved M-wave amplitude. However, the superimposed twitch force still decreased markedly more than the potentiated twitch force; with ITT this would reflect increased “voluntary activation.” In contrast, the superimposed twitch force was relatively spared when a similar protocol was performed in rat soleus bundles. Force relaxation was slowed by >150% in fatigued human muscles, whereas it was unchanged in rat soleus bundles. Accordingly, results similar to those in the human muscle were obtained when relaxation was slowed by cooling the rat soleus muscles. In conclusion, our data demonstrate that muscle fatigue can confound the quantification of central fatigue using the ITT.
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Affiliation(s)
- Daria Neyroud
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of LausanneLausanne, Switzerland; Department of Physiology, Faculty of Biology and Medicine, University of LausanneLausanne, Switzerland
| | - Arthur J Cheng
- Department of Physiology and Pharmacology, Karolinska Institutet Stockholm, Sweden
| | - Nicolas Bourdillon
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of LausanneLausanne, Switzerland; Department of Physiology, Faculty of Biology and Medicine, University of LausanneLausanne, Switzerland
| | - Bengt Kayser
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of LausanneLausanne, Switzerland; Department of Physiology, Faculty of Biology and Medicine, University of LausanneLausanne, Switzerland
| | - Nicolas Place
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of LausanneLausanne, Switzerland; Department of Physiology, Faculty of Biology and Medicine, University of LausanneLausanne, Switzerland
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet Stockholm, Sweden
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Bachasson D, Decorte N, Wuyam B, Millet GY, Verges S. Original Research: Central and peripheral quadriceps fatigue in young and middle-aged untrained and endurance-trained men: A comparative study. Exp Biol Med (Maywood) 2016; 241:1844-52. [PMID: 27287015 DOI: 10.1177/1535370216654225] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/19/2016] [Indexed: 11/17/2022] Open
Abstract
This study aimed to compare quadriceps function (i.e. strength, endurance, central, and peripheral fatigue) of young (Young-UnTr) and middle-aged (MidAge-UnTr) untrained men and young endurance-trained men (Young-Tr). Twenty-four male subjects (eight Young-UnTr (26 ± 4 yr), eight Young-Tr (29 ± 3 yr), and eight MidAge-UnTr (56 ± 4 yr) performed a maximal cycling test to assess their fitness level. On a separate visit, subjects performed sets of 10 intermittent (5-s on/5-s off) isometric contractions starting at 10% maximum voluntary contraction (MVC), with 10% MVC increments from one set to another until exhaustion. Electrophysiological and mechanical (e.g. twitch) evoked responses elicited with magnetic femoral nerve stimulation in the relaxed muscle and during MVC (i.e. estimation of voluntary activation using the interpolated twitch technique) were measured at baseline and after each set to assess peripheral and central fatigue, respectively. Endurance (= total number of contractions) was also evaluated. Young-UnTr exhibited larger reductions in evoked quadriceps mechanical responses than MidAge-UnTr and Young-Tr after identical standardized muscle loading (e.g. after the 50% MVC set, reduction in single potentiated twitch was -36 ± 9%, -21±16%, and -2 ± 4%, respectively). At both 50% MVC set and exhaustion, MidAge-UnTr exhibited similar reduction in maximal voluntary activation and displayed similar endurance compared to Young-UnTr. Young-Tr exhibited greater endurance than Young-UnTr without significant changes in maximal voluntary activation throughout the test. This study provides robust comparative data regarding the influence of chronic exposure to endurance training and middle-aged on central and peripheral quadriceps fatigability and endurance. Endurance-trained subjects showed smaller level of peripheral fatigue and displayed no significant central fatigue, even at exhaustion and despite greater endurance performance. Our findings also demonstrate that men in the sixth decade exhibit significant alterations in quadriceps function typically observed in much older subjects. These data emphasize the need for developing normative data for both central and peripheral quadriceps fatigability.
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Affiliation(s)
- Damien Bachasson
- Grenoble Alpes University, HP2 Laboratory, Grenoble 38000, France INSERM, Grenoble 38000, France Institute of Myology, Paris 75013, France
| | - Nicolas Decorte
- Grenoble Alpes University, HP2 Laboratory, Grenoble 38000, France INSERM, Grenoble 38000, France
| | - Bernard Wuyam
- Grenoble Alpes University, HP2 Laboratory, Grenoble 38000, France INSERM, Grenoble 38000, France
| | - Guillaume Y Millet
- INSERM, Grenoble 38000, France Laboratoire de Physiologie de l'Exercice, Université de Lyon, Saint-Etienne 42023, France Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary T2N 1N4, Canada
| | - Samuel Verges
- Grenoble Alpes University, HP2 Laboratory, Grenoble 38000, France INSERM, Grenoble 38000, France
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Contessa P, Puleo A, De Luca CJ. Is the notion of central fatigue based on a solid foundation? J Neurophysiol 2015; 115:967-77. [PMID: 26655823 DOI: 10.1152/jn.00889.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 12/02/2015] [Indexed: 11/22/2022] Open
Abstract
Exercise-induced muscle fatigue has been shown to be the consequence of peripheral factors that impair muscle fiber contractile mechanisms. Central factors arising within the central nervous system have also been hypothesized to induce muscle fatigue, but no direct empirical evidence that is causally associated to reduction of muscle force-generating capability has yet been reported. We developed a simulation model to investigate whether peripheral factors of muscle fatigue are sufficient to explain the muscle force behavior observed during empirical studies of fatiguing voluntary contractions, which is commonly attributed to central factors. Peripheral factors of muscle fatigue were included in the model as a time-dependent decrease in the amplitude of the motor unit force twitches. Our simulation study indicated that the force behavior commonly attributed to central fatigue could be explained solely by peripheral factors during simulated fatiguing submaximal voluntary contractions. It also revealed important flaws regarding the use of the interpolated twitch response from electrical stimulation of the muscle as a means for assessing central fatigue. Our analysis does not directly refute the concept of central fatigue. However, it raises important concerns about the manner in which it is measured and about the interpretation of the commonly accepted causes of central fatigue and questions the very need for the existence of central fatigue.
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Affiliation(s)
- Paola Contessa
- Delsys Incorporated, Natick, Massachusetts; Department of Physical Therapy and Athletic Training, Boston University, Boston, Massachusetts
| | - Alessio Puleo
- Delsys Incorporated, Natick, Massachusetts; Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy; and
| | - Carlo J De Luca
- Delsys Incorporated, Natick, Massachusetts; Department of Biomedical Engineering, Boston University, Boston, Massachusetts
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Prak RF, Doestzada M, Thomas CK, Tepper M, Zijdewind I. Reduced voluntary drive during sustained but not during brief maximal voluntary contractions in the first dorsal interosseous weakened by spinal cord injury. J Appl Physiol (1985) 2015; 119:1320-9. [PMID: 26404618 DOI: 10.1152/japplphysiol.00399.2015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Accepted: 09/22/2015] [Indexed: 11/22/2022] Open
Abstract
In able-bodied (AB) individuals, voluntary muscle activation progressively declines during sustained contractions. However, few data are available on voluntary muscle activation during sustained contractions in muscles weakened by spinal cord injury (SCI), where greater force declines may limit task performance. SCI-related impairment of muscle activation complicates interpretation of the interpolated twitch technique commonly used to assess muscle activation. We attempted to estimate and correct for the SCI-related-superimposed twitch. Seventeen participants, both AB and with SCI (American Spinal Injury Association Impairment Scale C/D) produced brief and sustained (2-min) maximal voluntary contractions (MVCs) with the first dorsal interosseous. Force and electromyography were recorded together with superimposed (doublet) twitches. MVCs of participants with SCI were weaker than those of AB participants (20.3 N, SD 7.1 vs. 37.9 N, SD 9.5; P < 0.001); MVC-superimposed twitches were larger in participants with SCI (SCI median 10.1%, range 2.0-63.2%; AB median 4.7%, range 0.0-18.4% rest twitch; P = 0.007). No difference was found after correction for the SCI-related-superimposed twitch (median 6.7%, 0.0-17.5% rest twitch, P = 0.402). Thus during brief contractions, the maximal corticofugal output that participants with SCI could exert was similar to that of AB participants. During the sustained contraction, force decline (SCI, 58.0%, SD 15.1; AB, 57.2% SD 13.3) was similar (P = 0.887) because participants with SCI developed less peripheral (P = 0.048) but more central fatigue than AB participants. The largest change occurred at the start of the sustained contraction when the (corrected) superimposed twitches increased more in participants with SCI (SCI, 16.3% rest twitch, SD 20.8; AB, 2.7%, SD 4.7; P = 0.01). The greater reduction in muscle activation after SCI may relate to a reduced capacity to overcome fast fatigue-related excitability changes at the spinal level.
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Affiliation(s)
- Roeland F Prak
- Department of Neuroscience, University Medical Center Groningen, University of Groningen, The Netherlands
| | - Marwah Doestzada
- Department of Neuroscience, University Medical Center Groningen, University of Groningen, The Netherlands
| | - Christine K Thomas
- The Miami Project to Cure Paralysis, Departments of Neurological Surgery, Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, Florida; and
| | - Marga Tepper
- Department of Rehabilitation Medicine, University Medical Center Groningen, Groningen, The Netherlands
| | - Inge Zijdewind
- Department of Neuroscience, University Medical Center Groningen, University of Groningen, The Netherlands;
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Beretta-Piccoli M, D’Antona G, Barbero M, Fisher B, Dieli-Conwright CM, Clijsen R, Cescon C. Evaluation of central and peripheral fatigue in the quadriceps using fractal dimension and conduction velocity in young females. PLoS One 2015; 10:e0123921. [PMID: 25880369 PMCID: PMC4400165 DOI: 10.1371/journal.pone.0123921] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 03/09/2015] [Indexed: 02/05/2023] Open
Abstract
PURPOSE Over the past decade, linear and non-linear surface electromyography descriptors for central and peripheral components of fatigue have been developed. In the current study, we tested fractal dimension (FD) and conduction velocity (CV) as myoelectric descriptors of central and peripheral fatigue, respectively. To this aim, we analyzed FD and CV slopes during sustained fatiguing contractions of the quadriceps femoris in healthy humans. METHODS A total of 29 recreationally active women (mean age±standard deviation: 24±4 years) and two female elite athletes (one power athlete, age 24 and one endurance athlete, age 30 years) performed two knee extensions: (1) at 20% maximal voluntary contraction (MVC) for 30 s, and (2) at 60% MVC held until exhaustion. Surface EMG signals were detected from the vastus lateralis and vastus medialis using bidimensional arrays. RESULTS Central and peripheral fatigue were described as decreases in FD and CV, respectively. A positive correlation between FD and CV (R=0.51, p<0.01) was found during the sustained 60% MVC, probably as a result of simultaneous motor unit synchronization and a decrease in muscle fiber CV during the fatiguing task. CONCLUSIONS Central and peripheral fatigue can be described as changes in FD and CV, at least in young, healthy women. The significant correlation between FD and CV observed at 60% MVC suggests that a mutual interaction between central and peripheral fatigue can arise during submaximal isometric contractions.
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Affiliation(s)
- Matteo Beretta-Piccoli
- Rehabilitation Research Laboratory, Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, SUPSI, Manno, Switzerland
- * E-mail:
| | - Giuseppe D’Antona
- Department of Molecular Medicine and Sport Medicine Centre Voghera, University of Pavia, Pavia, Italy
| | - Marco Barbero
- Rehabilitation Research Laboratory, Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, SUPSI, Manno, Switzerland
| | - Beth Fisher
- Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, United States of America
| | - Christina M. Dieli-Conwright
- Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, United States of America
| | - Ron Clijsen
- Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, SUPSI, Landquart, Switzerland
| | - Corrado Cescon
- Rehabilitation Research Laboratory, Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, SUPSI, Manno, Switzerland
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Children have a reduced maximal voluntary activation level of the adductor pollicis muscle compared to adults. Eur J Appl Physiol 2015; 115:1485-91. [PMID: 25694208 DOI: 10.1007/s00421-015-3132-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 02/09/2015] [Indexed: 10/24/2022]
Abstract
PURPOSE The role of nervous factors in the muscle strength difference between children and adults is debated, and the level of physical activity may confound this comparison. The purpose of this study was thus to compare, between children and adults, the maximal voluntary activation level (MVA) of the adductor pollicis (AP) muscle, which is weakly influenced by the level of physical activity. METHODS Thirteen boys (11.6 ± 0.1 years) and eight men (25.6 ± 1.5 years) were involved in this study. Neuromuscular function assessment included the evaluation of maximal voluntary contraction (MVC) force and of the MVA from peripheral magnetic stimulations of the ulnar nerve. The cross-sectional area of the AP muscle was determined with ultrasonography and used to calculate the specific force. A theoretical value of specific force, extrapolated for a full MVA, was finally computed (specific force@100 % MVA). RESULTS MVC force (66.8 ± 6.2 vs. 111.0 ± 4.5 N, respectively; P < 0.001) and MVA (85.0 ± 2.7 vs. 94.8 ± 1.4 %, respectively; P < 0.05) were significantly lower in children compared to adults. The specific force was lower in children compared to adults (46.8 ± 3.6 vs. 56.9 ± 2.5 N/cm(2), respectively; P < 0.05), but the specific force@100 % MVA did not differ between groups. CONCLUSION The results suggest that on an untrained muscle such as the AP muscle, the reduced ability of children to voluntarily activate their muscle could partly account for the difference of muscle strength between children and adults.
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Arnold P, Bautmans I. The influence of strength training on muscle activation in elderly persons: A systematic review and meta-analysis. Exp Gerontol 2014; 58:58-68. [DOI: 10.1016/j.exger.2014.07.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 06/23/2014] [Accepted: 07/23/2014] [Indexed: 01/21/2023]
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Fouré A, Nosaka K, Wegrzyk J, Duhamel G, Le Troter A, Boudinet H, Mattei JP, Vilmen C, Jubeau M, Bendahan D, Gondin J. Time course of central and peripheral alterations after isometric neuromuscular electrical stimulation-induced muscle damage. PLoS One 2014; 9:e107298. [PMID: 25215511 PMCID: PMC4162582 DOI: 10.1371/journal.pone.0107298] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 08/08/2014] [Indexed: 11/18/2022] Open
Abstract
Isometric contractions induced by neuromuscular electrostimulation (NMES) have been shown to result in a prolonged force decrease but the time course of the potential central and peripheral factors have never been investigated. This study examined the specific time course of central and peripheral factors after isometric NMES-induced muscle damage. Twenty-five young healthy men were subjected to an NMES exercise consisting of 40 contractions for both legs. Changes in maximal voluntary contraction force of the knee extensors (MVC), peak evoked force during double stimulations at 10 Hz (Db10) and 100 Hz (Db100), its ratio (10∶100), voluntary activation, muscle soreness and plasma creatine kinase activity were assessed before, immediately after and throughout four days after NMES session. Changes in knee extensors volume and T2 relaxation time were also assessed at two (D2) and four (D4) days post-exercise. MVC decreased by 29% immediately after NMES session and was still 19% lower than the baseline value at D4. The decrease in Db10 was higher than in Db100 immediately and one day post-exercise resulting in a decrease (−12%) in the 10∶100 ratio. On the contrary, voluntary activation significantly decreased at D2 (−5%) and was still depressed at D4 (−5%). Muscle soreness and plasma creatine kinase activity increased after NMES and peaked at D2 and D4, respectively. T2 was also increased at D2 (6%) and D4 (9%). Additionally, changes in MVC and peripheral factors (e.g., Db100) were correlated on the full recovery period, while a significant correlation was found between changes in MVC and VA only from D2 to D4. The decrease in MVC recorded immediately after the NMES session was mainly due to peripheral changes while both central and peripheral contributions were involved in the prolonged force reduction. Interestingly, the chronological events differ from what has been reported so far for voluntary exercise-induced muscle damage.
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Affiliation(s)
- Alexandre Fouré
- Aix-Marseille University, CNRS, CRMBM UMR CNRS 7339, Marseille, France
- * E-mail:
| | - Kazunori Nosaka
- Edith Cowan University, School of Exercise and Health Sciences, WA 6027, Joondalup, Australia
| | - Jennifer Wegrzyk
- Aix-Marseille University, CNRS, CRMBM UMR CNRS 7339, Marseille, France
| | - Guillaume Duhamel
- Aix-Marseille University, CNRS, CRMBM UMR CNRS 7339, Marseille, France
| | - Arnaud Le Troter
- Aix-Marseille University, CNRS, CRMBM UMR CNRS 7339, Marseille, France
| | - Hélène Boudinet
- APHM, La Timone Hospital, CEMEREM, Imaging Center, Marseille, France
| | - Jean-Pierre Mattei
- Aix-Marseille University, CNRS, CRMBM UMR CNRS 7339, Marseille, France
- APHM, La Conception Hospital, Department of Rheumatology, Marseille, France
| | - Christophe Vilmen
- Aix-Marseille University, CNRS, CRMBM UMR CNRS 7339, Marseille, France
| | - Marc Jubeau
- University of Nantes, Laboratory “Motricité, Interactions, Performance” (EA 4334), UFR STAPS, Nantes, France
| | - David Bendahan
- Aix-Marseille University, CNRS, CRMBM UMR CNRS 7339, Marseille, France
| | - Julien Gondin
- Aix-Marseille University, CNRS, CRMBM UMR CNRS 7339, Marseille, France
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Buckthorpe M, Erskine RM, Fletcher G, Folland JP. Task-specific neural adaptations to isoinertial resistance training. Scand J Med Sci Sports 2014; 25:640-9. [PMID: 25077768 DOI: 10.1111/sms.12292] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2014] [Indexed: 11/28/2022]
Abstract
This study aimed to delineate the contribution of adaptations in agonist, antagonist, and stabilizer muscle activation to changes in isometric and isoinertial lifting strength after short-term isoinertial resistance training (RT). Following familiarization, 45 men (23.2 ± 2.8 years) performed maximal isometric and isoinertial strength tests of the elbow flexors of their dominant arms before and after 3 weeks of isoinertial RT. During these tasks, surface electromyography (EMG) amplitude was recorded from the agonist (biceps brachii short and long heads), antagonist (triceps brachii lateral head), and stabilizer (anterior deltoid, pectoralis major) muscles and normalized to either Mmax (agonists) or to maximum EMG during relevant reference tasks (antagonist, stabilizers). After training, there was more than a twofold greater increase in training task-specific isoinertial than isometric strength (17% vs 7%). There were also task-specific adaptations in agonist EMG, with greater increases during the isoinertial than isometric strength task [analysis of variance (ANOVA), training × task, P = 0.005]. A novel finding of this study was that training increased stabilizer muscle activation during all the elbow flexion strength tasks (P < 0.001), although these were not task-specific training effects. RT elicited specific neural adaptations to the training task that appeared to explain the greater increase in isoinertial than isometric strength.
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Affiliation(s)
- M Buckthorpe
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,Isokinetic Medical Group, London, UK
| | - R M Erskine
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - G Fletcher
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - J P Folland
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
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Girard O, Racinais S. Combining heat stress and moderate hypoxia reduces cycling time to exhaustion without modifying neuromuscular fatigue characteristics. Eur J Appl Physiol 2014; 114:1521-32. [PMID: 24748530 PMCID: PMC4048668 DOI: 10.1007/s00421-014-2883-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 04/01/2014] [Indexed: 11/27/2022]
Abstract
Purpose This study investigated the isolated and combined effects of heat [temperate (22 °C/30 % rH) vs. hot (35 °C/40 % rH)] and hypoxia [sea level (FiO2 0.21) vs. moderate altitude (FiO2 0.15)] on exercise capacity and neuromuscular fatigue characteristics. Methods Eleven physically active subjects cycled to exhaustion at constant workload (66 % of the power output associated with their maximal oxygen uptake in temperate conditions) in four different environmental conditions [temperate/sea level (control), hot/sea level (hot), temperate/moderate altitude (hypoxia) and hot/moderate altitude (hot + hypoxia)]. Torque and electromyography (EMG) responses following electrical stimulation of the tibial nerve (plantar-flexion; soleus) were recorded before and 5 min after exercise. Results Time to exhaustion was reduced (P < 0.05) in hot (−35 ± 15 %) or hypoxia (−36 ± 14 %) compared to control (61 ± 28 min), while hot + hypoxia (−51 ± 20 %) further compromised exercise capacity (P < 0.05). However, the effect of temperature or altitude on end-exercise core temperature (P = 0.089 and P = 0.070, respectively) and rating of perceived exertion (P > 0.05) did not reach significance. Maximal voluntary contraction torque, voluntary activation (twitch interpolation) and peak twitch torque decreased from pre- to post-exercise (−9 ± 1, −4 ± 1 and −6 ± 1 % all trials compounded, respectively; P < 0.05), with no effect of the temperature or altitude. M-wave amplitude and root mean square activity were reduced (P < 0.05) in hot compared to temperate conditions, while normalized maximal EMG activity did not change. Altitude had no effect on any measured parameters. Conclusion Moderate hypoxia in combination with heat stress reduces cycling time to exhaustion without modifying neuromuscular fatigue characteristics. Impaired oxygen delivery or increased cardiovascular strain, increasing relative exercise intensity, may have also contributed to earlier exercise cessation.
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Affiliation(s)
- Olivier Girard
- Athlete Health and Performance Research Centre, Aspetar, Qatar Orthopaedic and Sports Medicine Hospital, PO Box 29222, Doha, Qatar,
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Li S, Liu J, Bhadane M, Zhou P, Rymer WZ. Activation deficit correlates with weakness in chronic stroke: evidence from evoked and voluntary EMG recordings. Clin Neurophysiol 2014; 125:2413-7. [PMID: 24747057 DOI: 10.1016/j.clinph.2014.03.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 03/04/2014] [Accepted: 03/20/2014] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To use evoked (M-wave) and voluntary (during maximal voluntary contraction (MVC)) EMG recordings to estimate the voluntary activation level in chronic stroke. METHODS Nine chronic hemiparetic stroke subjects participated in the experiment. M-wave (EMGM-wave) and MVC (EMGMVC) EMG values of the biceps brachii muscles were recorded. RESULTS Peak torque was significantly smaller on the impaired than non-impaired side. EMGM-wave was also significantly smaller on the impaired than non-impaired side. However, the normalized EMGM-wave/TorqueMVC ratio was not significantly different between two sides. In contrast, both absolute EMGMVC and normalized EMGMVC/TorqueMVC were smaller on the impaired than non-impaired side. The voluntary activation level, EMGMVC/M-wave, was also smaller on the impaired than non-impaired side. The voluntary activation level on the impaired side was highly correlated with weakness (R=0.72), but very low (R=0.32) on the non-impaired side. CONCLUSION Collectively, our findings suggest that both peripheral and central factors contribute to post-stroke weakness, but activation deficit correlates most closely with weakness as estimated from maximum voluntary torque generation. SIGNIFICANCE These findings serve to highlight the potential benefit from high-intensity exercises to enhance central activation for facilitation of motor recovery.
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Affiliation(s)
- Sheng Li
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center - Houston, Houston, TX 77030, United States; Neurorehabilitation Research Laboratory, TIRR Memorial Hermann Hospital, Houston, TX 77030, United States.
| | - Jie Liu
- Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, United States
| | - Minal Bhadane
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center - Houston, Houston, TX 77030, United States; Neurorehabilitation Research Laboratory, TIRR Memorial Hermann Hospital, Houston, TX 77030, United States
| | - Ping Zhou
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center - Houston, Houston, TX 77030, United States; Biomedical Engineering Program, University of Science and Technology of China, Hefei, China
| | - W Zev Rymer
- Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, United States
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Bennell K, Hinman RS, Wrigley TV, Creaby MW, Hodges P. Exercise and osteoarthritis: cause and effects. Compr Physiol 2013; 1:1943-2008. [PMID: 23733694 DOI: 10.1002/cphy.c100057] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Osteoarthritis (OA) is a common chronic joint condition predominantly affecting the knee, hip, and hand joints. Exercise plays a role in the development and treatment of OA but most of the literature in this area relates to knee OA. While studies indicate that exercise and physical activity have a generally positive effect on healthy cartilage metrics, depending upon the type of the activity and its intensity, the risk of OA development does appear to be moderately increased with sporting participation. In particular, joint injury associated with sports participation may be largely responsible for this increased risk of OA with sport. Various repetitive occupational tasks are also linked to greater likelihood of OA development. There are a number of physical impairments associated with OA including pain, muscle weakness and altered muscle function, reduced proprioception and postural control, joint instability, restricted range of motion, and lower aerobic fitness. These can result directly from the OA pathological process and/or indirectly as a result of factors such as pain, effusion, and reduced activity levels. These impairments and their underlying physiology are often targeted by exercise interventions and evidence generally shows that many of these can be modified by specific exercise. There is currently little clinical trial evidence to show that exercise can alter mechanical load and structural disease progression in those with established OA, although a number of impairments, that are amenable to change with exercise, appears to be associated with increased mechanical load and/or disease progression in longitudinal studies.
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Affiliation(s)
- Kim Bennell
- Centre for Health, Exercise and Sports Medicine, Department of Physiotherapy, University of Melbourne, Australia.
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Girard O, Bishop DJ, Racinais S. Neuromuscular adjustments of the quadriceps muscle after repeated cycling sprints. PLoS One 2013; 8:e61793. [PMID: 23650503 PMCID: PMC3641084 DOI: 10.1371/journal.pone.0061793] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 03/13/2013] [Indexed: 11/19/2022] Open
Abstract
PURPOSE This study investigated the supraspinal processes of fatigue of the quadriceps muscle in response to repeated cycling sprints. METHODS Twelve active individuals performed 10 × 6-s "all-out" sprints on a cycle ergometer (recovery = 30 s), followed 6 min later by 5 × 6-s sprints (recovery = 30 s). Transcranial magnetic and electrical femoral nerve stimulations during brief (5-s) and sustained (30-s) isometric contractions of the knee extensors were performed before and 3 min post-exercise. RESULTS Maximal strength of the knee extensors decreased during brief and sustained contractions (~11% and 9%, respectively; P<0.001). Peripheral and cortical voluntary activation, motor evoked potential amplitude and silent period duration responses measured during briefs contractions were unaltered (P>0.05). While cortical voluntary activation declined (P<0.01) during the sustained maximal contraction in both test sessions, larger reductions occurred (P<0.05) after exercise. Lastly, resting twitch amplitude in response to both femoral nerve and cortical stimulations was largely (> 40%) reduced (P<0.001) following exercise. CONCLUSION The capacity of the motor cortex to optimally drive the knee extensors following a repeated-sprint test was shown in sustained, but not brief, maximal isometric contractions. Additionally, peripheral factors were largely involved in the exercise-induced impairment in neuromuscular function, while corticospinal excitability was well-preserved.
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Affiliation(s)
- Olivier Girard
- Aspetar, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
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Abstract
The purpose of this brief review is to examine our current knowledge of the neural control of eccentric contractions. The review focuses on three main issues. The first issue considers the ability of individuals to activate muscles maximally during eccentric contractions. Most studies indicate that, regardless of the experimental approach (surface EMG amplitude, twitch superimposition, and motor unit recordings), it is usually more difficult to achieve full activation of a muscle by voluntary command during eccentric contractions than during concentric and isometric contractions. The second issue is related to the specificity of the control strategy used by the central nervous system during submaximal eccentric contractions. This part underscores that although the central nervous system appears to employ a single size-related strategy to activate motoneurons during the different types of contractions, the discharge rate of motor units is less during eccentric contractions across different loading conditions. The last issue addresses the mechanisms that produce this specific neural activation. This section indicates that neural adjustments at both supraspinal and spinal levels contribute to the specific modulation of voluntary activation during eccentric contractions. Although the available information on the control of eccentric contractions has increased during the last two decades, this review indicates that the exact mechanisms underlying the unique neural modulation observed in this type of contraction at spinal and supraspinal levels remains unknown and their understanding represents, therefore, a major challenge for future research on this topic.
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Affiliation(s)
- Jacques Duchateau
- Laboratory of Applied Biology, ULB Neurosciences Institute, Université Libre de Bruxelles, Brussels, Belgium
| | - Stéphane Baudry
- Laboratory of Applied Biology, ULB Neurosciences Institute, Université Libre de Bruxelles, Brussels, Belgium
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Millet G, Bachasson D, Temesi J, Wuyam B, Féasson L, Vergès S, Lévy P. Potential interests and limits of magnetic and electrical stimulation techniques to assess neuromuscular fatigue. Neuromuscul Disord 2012. [DOI: 10.1016/j.nmd.2012.10.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Burnley M, Vanhatalo A, Jones AM. Distinct profiles of neuromuscular fatigue during muscle contractions below and above the critical torque in humans. J Appl Physiol (1985) 2012; 113:215-23. [DOI: 10.1152/japplphysiol.00022.2012] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Whether the transition in fatigue processes between “low-intensity” and “high-intensity” contractions occurs gradually, as the torque requirements are increased, or whether this transition occurs more suddenly at some identifiable “threshold”, is not known. We hypothesized that the critical torque (CT; the asymptote of the torque-duration relationship) would demarcate distinct profiles of central and peripheral fatigue during intermittent isometric quadriceps contractions (3-s contraction, 2-s rest). Nine healthy men performed seven experimental trials to task failure or for up to 60 min, with maximal voluntary contractions (MVCs) performed at the end of each minute. The first five trials were performed to determine CT [∼35–55% MVC, denoted severe 1 (S1) to severe 5 (S5) in ascending order], while the remaining two trials were performed 10 and 20% below the CT (denoted CT-10% and CT-20%). Dynamometer torque and the electromyogram of the right vastus lateralis were sampled continuously. Peripheral and central fatigue was determined from the fall in potentiated doublet torque and voluntary activation, respectively. Above CT, contractions progressed to task failure in ∼3–18 min, at which point the MVC did not differ from the target torque (S1 target, 88.7 ± 4.3 N·m vs. MVC, 89.3 ± 8.8 N·m, P = 0.94). The potentiated doublet fell significantly in all trials, and voluntary activation was reduced in trials S1–S3, but not trials S4 and S5. Below CT, contractions could be sustained for 60 min on 17 of 18 occasions. Both central and peripheral fatigue developed, but there was a substantial reserve in MVC torque at the end of the task. The rate of global and peripheral fatigue development was four to five times greater during S1 than during CT-10% (change in MVC/change in time S1 vs. CT-10%: −7.2 ± 1.4 vs. −1.5 ± 0.4 N·m·min−1). These results demonstrate that CT represents a critical threshold for neuromuscular fatigue development.
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Affiliation(s)
- Mark Burnley
- Department of Sport and Exercise Science, Aberystwyth University, Ceredigion, United Kingdom; and
| | - Anni Vanhatalo
- College of Life and Environmental Sciences, University of Exeter, Devon, United Kingdom
| | - Andrew M. Jones
- College of Life and Environmental Sciences, University of Exeter, Devon, United Kingdom
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Girard O, Bishop DJ, Racinais S. Hot conditions improve power output during repeated cycling sprints without modifying neuromuscular fatigue characteristics. Eur J Appl Physiol 2012; 113:359-69. [PMID: 22743981 DOI: 10.1007/s00421-012-2444-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 06/13/2012] [Indexed: 11/24/2022]
Abstract
This study investigated the effect of hot conditions on repeated sprint cycling performance and post-exercise alterations in isometric knee extension function. Twelve physically active participants performed 10 × 6-s "all-out" sprints on a cycle ergometer (recovery = 30 s), followed 6 min later by 5 × 6-s sprints (recovery = 30 s) in either a neutral (24 °C/30 %rH) or a hot (35 °C/40 %rH) environment. Neuromuscular tests including voluntary and electrically evoked isometric contractions of the knee extensors were performed before and after exercise. Average core temperature during exercise was higher (38.0 ± 0.1 vs. 37.7 ± 0.1 °C, respectively; P < 0.05) in hot versus neutral environments. Peak power output decreased (-17.9 % from sprint 1 to sprint 10 and -17.0 % from sprint 11 to sprint 15; P < 0.001) across repetitions. Average peak power output during the first ten sprints was higher (+3.1 %; P < 0.01) in the hot ambient temperature condition. Maximal strength (-12 %) and rate of force development (-15 to -26 %, 30-200 ms from the onset of contraction) decreased (P < 0.001) during brief contractions after exercise, irrespectively of the ambient temperature. During brief maximal contractions, changes in voluntary activation (~80 %) were not affected by exercise or temperature. Voluntary activation declined (P < 0.01) during the sustained contraction, with these reductions being more pronounced (P < 0.05) after exercise but not affected by the ambient temperature. Resting twitch amplitude declined (P < 0.001) by ~42 %, independently of the ambient temperature. In conclusion, heat exposure has no effect on the pattern and the extent of isometric knee extensor fatigue following repeated cycling sprints in the absence of hyperthermia.
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Affiliation(s)
- Olivier Girard
- Research and Education Centre, ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
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Van Leeuwen DM, De Ruiter CJ, De Haan A. Effect of stimulation intensity on assessment of voluntary activation. Muscle Nerve 2012; 45:841-8. [DOI: 10.1002/mus.23343] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Steens A, de Vries A, Hemmen J, Heersema T, Heerings M, Maurits N, Zijdewind I. Fatigue perceived by multiple sclerosis patients is associated with muscle fatigue. Neurorehabil Neural Repair 2011; 26:48-57. [PMID: 21856990 DOI: 10.1177/1545968311416991] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Fatigue is a debilitating symptom in multiple sclerosis (MS). Previous studies showed no association between fatigue as perceived by the patient and physiological measures of fatigability. OBJECTIVE The authors investigated associations between perceived fatigue and measures of fatigability after correction for differences in maximal voluntary contraction (MVC). METHODS A total of 20 people with relapsing-remitting MS with an Extended Disability Severity Score less than 5.5 and 20 healthy controls filled out the Fatigue Severity Score questionnaire of perceived fatigue. The authors obtained the MVC from the first dorsal interosseus muscle, voluntary muscle activation, and force decline during a sustained MVC (124 s, muscle fatigue). RESULTS Patients perceived increased levels of fatigue compared with controls (P < .001). Although patients and controls developed similar amounts of muscle fatigue during the sustained contraction, a linear regression model that included both muscle fatigue and MVC was positively associated with perceived fatigue in patients only (R (2) = 0.45; P = .01). Voluntary activation during the sustained contraction was negatively associated with perceived fatigue (R (2) = 0.25; P = .02). CONCLUSION The data indicate that fatigue perceived by MS patients is associated with measures of fatigability. This observation helps in the understanding of mechanisms underlying the increased levels of fatigue perceived by MS patients. These data also emphasize that for comparison of fatigue-related parameters between groups, correction for individual maximal force is essential.
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Affiliation(s)
- Anneke Steens
- Deptartment of Neuroscience, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
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47
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Hortobágyi T, Maffiuletti NA. Neural adaptations to electrical stimulation strength training. Eur J Appl Physiol 2011; 111:2439-49. [PMID: 21643920 PMCID: PMC3175340 DOI: 10.1007/s00421-011-2012-2] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 05/18/2011] [Indexed: 01/26/2023]
Abstract
This review provides evidence for the hypothesis that electrostimulation strength training (EST) increases the force of a maximal voluntary contraction (MVC) through neural adaptations in healthy skeletal muscle. Although electrical stimulation and voluntary effort activate muscle differently, there is substantial evidence to suggest that EST modifies the excitability of specific neural paths and such adaptations contribute to the increases in MVC force. Similar to strength training with voluntary contractions, EST increases MVC force after only a few sessions with some changes in muscle biochemistry but without overt muscle hypertrophy. There is some mixed evidence for spinal neural adaptations in the form of an increase in the amplitude of the interpolated twitch and in the amplitude of the volitional wave, with less evidence for changes in spinal excitability. Cross-sectional and exercise studies also suggest that the barrage of sensory and nociceptive inputs acts at the cortical level and can modify the motor cortical output and interhemispheric paths. The data suggest that neural adaptations mediate initial increases in MVC force after short-term EST.
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Affiliation(s)
- Tibor Hortobágyi
- Center for Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
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48
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Electrical stimulation for testing neuromuscular function: from sport to pathology. Eur J Appl Physiol 2011; 111:2489-500. [PMID: 21590274 DOI: 10.1007/s00421-011-1996-y] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Accepted: 05/02/2011] [Indexed: 10/18/2022]
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Abstract
In 2008, we published an article arguing that the age-related loss of muscle strength is only partially explained by the reduction in muscle mass and that other physiologic factors explain muscle weakness in older adults (Clark BC, Manini TM. Sarcopenia =/= dynapenia. J Gerontol A Biol Sci Med Sci. 2008;63:829-834). Accordingly, we proposed that these events (strength and mass loss) be defined independently, leaving the term "sarcopenia" to be used in its original context to describe the age-related loss of muscle mass. We subsequently coined the term "dynapenia" to describe the age-related loss of muscle strength and power. This article will give an update on both the biological and clinical literature on dynapenia-serving to best synthesize this translational topic. Additionally, we propose a working decision algorithm for defining dynapenia. This algorithm is specific to screening for and defining dynapenia using age, presence or absence of risk factors, a grip strength screening, and if warranted a test for knee extension strength. A definition for a single risk factor such as dynapenia will provide information in building a risk profile for the complex etiology of physical disability. As such, this approach mimics the development of risk profiles for cardiovascular disease that include such factors as hypercholesterolemia, hypertension, hyperglycemia, etc. Because of a lack of data, the working decision algorithm remains to be fully developed and evaluated. However, these efforts are expected to provide a specific understanding of the role that dynapenia plays in the loss of physical function and increased risk for disability among older adults.
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Affiliation(s)
- Todd M Manini
- Institute on Aging and Department of Aging and Geriatric Research, University of Florida, Gainesville, FL 32611, USA.
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50
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Clark DJ, Fielding RA. Neuromuscular contributions to age-related weakness. J Gerontol A Biol Sci Med Sci 2011; 67:41-7. [PMID: 21415261 DOI: 10.1093/gerona/glr041] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Declines in skeletal muscle mass and quality are important factors contributing to age-related weakness. Neural activation of agonist and antagonist muscles may also be important contributing factors. METHODS We conducted a review of the scientific literature on older adults to determine (a) methodologies used to quantify activation, (b) the potential role of agonist and antagonist activation on weakness, and (c) some possible neurophysiological mechanisms that may underlie impaired activation. RESULTS The cumulative evidence indicates that agonist activation is impaired in some, but not all, older adults and that this impairment contributes to age-related weakness. It is possible that antagonist coactivation also plays a role in age-related weakness, though a definitive link has not been established. CONCLUSION Future research should focus on improving quantitative measurement and mechanistic understanding of impaired activation with aging.
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Affiliation(s)
- David J Clark
- Brain Rehabilitation Research Center, Malcom Randall Veterans Affairs Medical Center, Gainesville, Florida, USA
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