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Cavalcante JGT, Ribeiro VHDS, Marqueti RDC, Paz IDA, Bastos JAI, Vaz MA, Babault N, Durigan JLQ. Effect of muscle length on maximum evoked torque, discomfort, contraction fatigue, and strength adaptations during electrical stimulation in adult populations: A systematic review. PLoS One 2024; 19:e0304205. [PMID: 38857245 PMCID: PMC11164398 DOI: 10.1371/journal.pone.0304205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 05/08/2024] [Indexed: 06/12/2024] Open
Abstract
Neuromuscular electrical stimulation (NMES) can improve physical function in different populations. NMES-related outcomes may be influenced by muscle length (i.e., joint angle), a modulator of the force generation capacity of muscle fibers. Nevertheless, to date, there is no comprehensive synthesis of the available scientific evidence regarding the optimal joint angle for maximizing the effectiveness of NMES. We performed a systematic review to investigate the effect of muscle length on NMES-induced torque, discomfort, contraction fatigue, and strength training adaptations in healthy and clinical adult populations (PROSPERO: CRD42022332965). We conducted searches across seven electronic databases: PUBMED, Web of Science, EMBASE, PEDro, BIREME, SCIELO, and Cochrane, over the period from June 2022 to October 2023, without restricting the publication year. We included cross-sectional and longitudinal studies that used NMES as an intervention or assessment tool for comparing muscle lengths in adult populations. We excluded studies on vocalization, respiratory, or pelvic floor muscles. Data extraction was performed via a standardized form to gather information on participants, interventions, and outcomes. Risk of bias was assessed using the Revised Cochrane risk-of-bias tool for cross-over trials and the Physiotherapy Evidence Database scale. Out of the 1185 articles retrieved through our search strategy, we included 36 studies in our analysis, that included 448 healthy young participants (age: 19-40 years) in order to investigate maximum evoked torque (n = 268), contraction fatigability (n = 87), discomfort (n = 82), and muscle strengthening (n = 22), as well as six participants with spinal cord injuries, and 15 healthy older participants. Meta-analyses were possible for comparing maximal evoked torque according to quadriceps muscle length through knee joint angle. At optimal muscle length 50° - 70° of knee flexion, where 0° is full extension), there was greater evoked torque during nerve stimulation compared to very short (0 - 30°) (p<0.001, CI 95%: -2.03, -1.15 for muscle belly stimulation, and -3.54, -1.16 for femoral nerve stimulation), short (31° - 49°) (p = 0.007, CI 95%: -1.58, -0.25), and long (71° - 90°) (p<0.001, CI 95%: 0.29, 1.02) muscle lengths. At long muscle lengths, NMES evoked greater torque than very short (p<0.001, CI 95%: -2.50, -0.67) and short (p = 0.04, CI 95%: -2.22, -0.06) lengths. The shortest quadriceps length generated the highest perceived discomfort for a given current amplitude. The amount of contraction fatigability was greater when muscle length allowed greater torque generation in the pre-fatigue condition. Strength gains were greater for a protocol at the optimal muscle length than for short muscle length. The quality of evidence was very high for most comparisons for evoked torque. However, further studies are necessary to achieve certainty for the other outcomes. Optimal muscle length should be considered the primary choice during NMES interventions, as it promotes higher levels of force production and may facilitate the preservation/gain in muscle force and mass, with reduced discomfort. However, a longer than optimal muscle length may also be used, due to possible muscle lengthening at high evoked tension. Thorough understanding of these physiological principles is imperative for the appropriate prescription of NMES for healthy and clinical populations.
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Affiliation(s)
- Jonathan Galvão Tenório Cavalcante
- Laboratory of Muscle and Tendon Plasticity, Graduate Program of Physical Education, University of Brasília, Brasília, Distrito Federal, Brazil
| | - Victor Hugo de Souza Ribeiro
- Laboratory of Muscle and Tendon Plasticity, Graduate Program of Rehabilitation Sciences, University of Brasília, Brasília, Distrito Federal, Brazil
| | - Rita de Cássia Marqueti
- Molecular Analysis Laboratory, Graduate Program of Rehabilitation Sciences, University of Brasília, Brasília, Distrito Federal, Brazil
| | - Isabel de Almeida Paz
- Exercise Research Laboratory, School of Physical Education, Physical Therapy and Dance, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Júlia Aguillar Ivo Bastos
- Laboratory of Muscle and Tendon Plasticity, Graduate Program of Rehabilitation Sciences, University of Brasília, Brasília, Distrito Federal, Brazil
| | - Marco Aurélio Vaz
- Exercise Research Laboratory, School of Physical Education, Physical Therapy and Dance, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Nicolas Babault
- Centre d’Expertise de la Performance, INSERM UMR1093-CAPS, UFR des Sciences du Sport, University of Burgundy Franche-Comté, Besançon, Dijon, France
| | - João Luiz Quagliotti Durigan
- Laboratory of Muscle and Tendon Plasticity, Graduate Program of Physical Education, University of Brasília, Brasília, Distrito Federal, Brazil
- Laboratory of Muscle and Tendon Plasticity, Graduate Program of Rehabilitation Sciences, University of Brasília, Brasília, Distrito Federal, Brazil
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McMahon G, Onambele-Pearson G. Joint angle-specific neuromuscular time course of recovery after isometric resistance exercise at shorter and longer muscle lengths. J Appl Physiol (1985) 2024; 136:889-900. [PMID: 38450425 DOI: 10.1152/japplphysiol.00820.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 02/29/2024] [Accepted: 02/29/2024] [Indexed: 03/08/2024] Open
Abstract
Resistance training at longer muscle lengths induces greater muscle hypertrophy and different neuromuscular functional adaptations than training at shorter muscle lengths. However, the acute time course of recovery of neuromuscular characteristics after resistance exercise at shorter and longer muscle lengths in the quadriceps has never been described. Eight healthy young participants (4 M, 4 F) were randomly assigned to perform four sets of eight maximal isometric contractions at shorter (SL; 50° knee flexion) or longer (LL; 90° knee flexion) muscle lengths in a crossover fashion. During exercise, peak torque (PT), muscle activity [electromyogram (EMG)], and internal muscle forces were assessed. PT and EMG at shorter (PT50, EMG50) and longer (PT90, EMG90) muscle lengths, creatine kinase (CK), and muscle soreness were measured at baseline, immediately after exercise (Post), after 24 h (24 h), and after 48 h (48 h). During exercise, EMG (P = 0.002) and internal muscle forces (P = 0.017) were greater in LL than in SL. During recovery, there was a main effect of exercise angle, with PT50 (P = 0.002), PT90 (P = 0.016), and EMG50 (P = 0.002) all significantly reduced to a greater degree in LL compared with SL. CK and muscle soreness increased after resistance exercise, but there were no differences between SL and LL. The present results suggest that if the preceding isometric resistance exercise is performed at longer muscle lengths, function and muscle activity at shorter and longer muscle lengths are inhibited to a larger degree in the subsequent recovery period. This information can be used by practitioners to manipulate exercise prescription.NEW & NOTEWORTHY Despite the established long-term benefits of training at longer muscle lengths for muscle size and strength, acutely performing resistance exercise at longer muscle lengths may require a longer time course of neuromuscular recovery compared with performing resistance exercises at shorter muscle lengths. Furthermore, there appear to be different joint angle-specific recovery profiles, depending on the muscle length of the preceding exercise.
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Affiliation(s)
- Gerard McMahon
- Sport and Exercise Sciences Research Institute, School of Sport, Ulster University, Belfast, United Kingdom
| | - Gladys Onambele-Pearson
- Research Centre for MusculoSkeletal Sciences & Sport Medicine, Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, United Kingdom
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Ortega DG, Housh TJ, Smith RW, Arnett JE, Neltner TJ, Anders JPV, Schmidt RJ, Johnson GO. Effects of a Sustained, Isometric Forearm Flexion Task to Failure on Torque and Neuromuscular Responses at 3 Elbow Joint Angles. J Strength Cond Res 2024; 38:e25-e33. [PMID: 38085633 DOI: 10.1519/jsc.0000000000004599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
ABSTRACT Ortega, DG, Housh, TJ, Smith, RW, Arnett, JE, Neltner, TJ, Anders, JPV, Schmidt, RJ, and Johnson, GO. The effects of a sustained, isometric forearm flexion task to failure on torque and neuromuscular responses at 3 elbow joint angles. J Strength Cond Res 38(1): e25-e33, 2024-This study examined the effects of a sustained, isometric forearm flexion task anchored to torque to task failure on maximal voluntary isometric contraction (MVIC) and neuromuscular responses at 3 elbow joint angles. Eleven women (mean ± SD: age = 20.8 ± 2.7 years, height = 169.3 ± 7.4 cm, body mass = 67.7 ± 6.9 kg) performed two 3s forearm flexion MVICs at elbow joint angles (JAs) of 75°, 100°, and 125° before and after a sustained, isometric forearm flexion task to failure at a fatiguing joint angle of 100° anchored to a torque value that corresponded to a rating of perceived exertion of 8 (RPE = 8). The amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) and mechanomyographic (MMG) signals were recorded from the biceps brachii. Repeated-measures ANOVAs were used to compare mean differences for MVIC and neuromuscular parameters. Collapsed across JAs, MVIC (p < 0.001) and EMG MPF (p = 0.006) pretest values were greater than posttest values. Collapsed across time, EMG MPF at JA75 was greater than JA100 (p < 0.001) and JA125 (p < 0.001), and JA100 was greater (p = 0.007) than JA125. For EMG AMP, there was a fatigue-induced decrease at JA75 (p = 0.003). For neuromuscular efficiency (NME = normalized torque/normalized EMG AMP), there were decreases from pretest to posttest at JA100 (p = 0.002) and JA125 (p = 0.008). There were no significant interactions or main effects for MMG AMP and MMG MPF. From these findings, it was hypothesized that the decline in MVICs at JA75, JA100, and JA125 was due to fatigue-induced metabolic perturbations that resulted in JA-specific neuromuscular responses. Thus, neuromuscular parameters may provide insight into the JA-specific mechanisms of fatigue.
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Affiliation(s)
- Dolores G Ortega
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - Terry J Housh
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - Robert W Smith
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - Jocelyn E Arnett
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - Tyler J Neltner
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - John Paul V Anders
- Department of Human Sciences, The Exercise Science Program, The Ohio State University, Columbus, Ohio
| | - Richard J Schmidt
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - Glen O Johnson
- Department of Nutrition and Health Sciences, Exercise Physiology Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska; and
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Brouwer NP, Kingma I, van Dijk W, van Dieën JH. Can intermittent changes in trunk extensor muscle length delay muscle fatigue development? J Biomech 2024; 162:111881. [PMID: 38049364 DOI: 10.1016/j.jbiomech.2023.111881] [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: 08/23/2023] [Revised: 11/01/2023] [Accepted: 11/19/2023] [Indexed: 12/06/2023]
Abstract
Muscle length changes may evoke alternating activity and consequently reduce local fatigue and pain during prolonged static bending. The aim of this study was to assess whether a postural intervention involving intermittent trunk extensor muscle length changes (INTERMITTENT) can delay muscle fatigue during prolonged static bending when compared to a near-isometric condition (ISOMETRIC) or when participants were allowed to voluntarily vary muscle length (VOLUNTARY). These three conditions were completed by 11 healthy fit male participants, in three separate sessions of standing with 30 ± 3 degrees trunk inclination until exhaustion. Conventional and high-density electromyography (convEMG and HDsEMG, respectively) were measured on the left and right side of the spine, respectively. The endurance time for INTERMITTENT was 33.6% greater than ISOMETRIC (95% CI: [3.8, 63.5]; p = 0.027) and 29.4% greater than VOLUNTARY (95% CI: [7.0, 51.7]; p = 0.010), but not different between ISOMETRIC and VOLUNTARY. The convEMG and HDsEMG amplitude coefficient of variation was significantly greater for INTERMITTENT versus ISOMETRIC. The rate of change in convEMG and HDsEMG spectral content did not reveal significant differences between conditions as found in endurance time. Additional regression analyses between endurance time and rate of change in convEMG (p > 0.05) and HDsEMG (R2 = 0.39-0.65, p = 0.005-0.039) spectral content indicated that HDsEMG better reflects fatigue development in low-level contractions. In conclusion, imposed intermittent trunk extensor muscle length changes delayed muscle fatigue development when compared to a near-isometric condition or when participants were allowed to voluntarily vary muscle length, possibly due to evoking alternating activity between/within trunk extensor muscles.
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Affiliation(s)
- Niels P Brouwer
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands
| | - Idsart Kingma
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands
| | | | - Jaap H van Dieën
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands.
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Zeng W, Hume DR, Lu Y, Fitzpatrick CK, Babcock C, Myers CA, Rullkoetter PJ, Shelburne KB. Modeling of active skeletal muscles: a 3D continuum approach incorporating multiple muscle interactions. Front Bioeng Biotechnol 2023; 11:1153692. [PMID: 37274172 PMCID: PMC10234509 DOI: 10.3389/fbioe.2023.1153692] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 05/10/2023] [Indexed: 06/06/2023] Open
Abstract
Skeletal muscles have a highly organized hierarchical structure, whose main function is to generate forces for movement and stability. To understand the complex heterogeneous behaviors of muscles, computational modeling has advanced as a non-invasive approach to evaluate relevant mechanical quantities. Aiming to improve musculoskeletal predictions, this paper presents a framework for modeling 3D deformable muscles that includes continuum constitutive representation, parametric determination, model validation, fiber distribution estimation, and integration of multiple muscles into a system level for joint motion simulation. The passive and active muscle properties were modeled based on the strain energy approach with Hill-type hyperelastic constitutive laws. A parametric study was conducted to validate the model using experimental datasets of passive and active rabbit leg muscles. The active muscle model with calibrated material parameters was then implemented to simulate knee bending during a squat with multiple quadriceps muscles. A computational fluid dynamics (CFD) fiber simulation approach was utilized to estimate the fiber arrangements for each muscle, and a cohesive contact approach was applied to simulate the interactions among muscles. The single muscle simulation results showed that both passive and active muscle elongation responses matched the range of the testing data. The dynamic simulation of knee flexion and extension showed the predictive capability of the model for estimating the active quadriceps responses, which indicates that the presented modeling pipeline is effective and stable for simulating multiple muscle configurations. This work provided an effective framework of a 3D continuum muscle model for complex muscle behavior simulation, which will facilitate additional computational and experimental studies of skeletal muscle mechanics. This study will offer valuable insight into the future development of multiscale neuromuscular models and applications of these models to a wide variety of relevant areas such as biomechanics and clinical research.
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Affiliation(s)
- Wei Zeng
- Center for Orthopaedic Biomechanics, University of Denver, Denver, CO, United States
- Department of Mechanical Engineering, New York Institute of Technology, New York, NY, United States
| | - Donald R. Hume
- Center for Orthopaedic Biomechanics, University of Denver, Denver, CO, United States
| | - Yongtao Lu
- Department of Engineering Mechanics, Dalian University of Technology, Dalian, China
| | - Clare K. Fitzpatrick
- Mechanical and Biomedical Engineering, Boise State University, Boise, ID, United States
| | - Colton Babcock
- Mechanical and Biomedical Engineering, Boise State University, Boise, ID, United States
| | - Casey A. Myers
- Center for Orthopaedic Biomechanics, University of Denver, Denver, CO, United States
| | - Paul J. Rullkoetter
- Center for Orthopaedic Biomechanics, University of Denver, Denver, CO, United States
| | - Kevin B. Shelburne
- Center for Orthopaedic Biomechanics, University of Denver, Denver, CO, United States
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Fatigue-induced changes in knee-extensor torque complexity and muscle metabolic rate are dependent on joint angle. Eur J Appl Physiol 2021; 121:3117-3131. [PMID: 34355267 PMCID: PMC8505307 DOI: 10.1007/s00421-021-04779-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 07/25/2021] [Indexed: 01/20/2023]
Abstract
Purpose Joint angle is a significant determinant of neuromuscular and metabolic function. We tested the hypothesis that previously reported correlations between knee-extensor torque complexity and metabolic rate (\documentclass[12pt]{minimal}
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\begin{document}$${\text{m}\dot{\text{V}}\text{O}}_{{2}}$$\end{document}mV˙O2) would be conserved at reduced joint angles (i.e. shorter muscle lengths). Methods Eleven participants performed intermittent isometric knee-extensor contractions at 50% maximum voluntary torque for 30 min or until task failure (whichever occurred sooner) at joint angles of 30º, 60º and 90º of flexion (0º = extension). Torque and surface EMG were sampled continuously. Complexity and fractal scaling of torque were quantified using approximate entropy (ApEn) and detrended fluctuation analysis (DFA) α. \documentclass[12pt]{minimal}
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\begin{document}$${\text{m}\dot{\text{V}}\text{O}}_{{2}}$$\end{document}mV˙O2 was determined using near-infrared spectroscopy. Results Time to task failure/end increased as joint angle decreased (P < 0.001). Over time, complexity decreased at 90º and 60º (decreased ApEn, increased DFA α, both P < 0.001), but not 30º. \documentclass[12pt]{minimal}
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\begin{document}$${\text{m}\dot{\text{V}}\text{O}}_{{2}}$$\end{document}mV˙O2 increased at all joint angles (P < 0.001), though the magnitude of this increase was lower at 30º compared to 60º and 90º (both P < 0.01). There were significant correlations between torque complexity and \documentclass[12pt]{minimal}
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\begin{document}$${\text{m}\dot{\text{V}}\text{O}}_{{2}}$$\end{document}mV˙O2 at 90º (ApEn, r = − 0.60, P = 0.049) and 60º (ApEn, r = − 0.64, P = 0.035; DFA α, ρ = 0.68, P = 0.015). Conclusion The lack of correlation between \documentclass[12pt]{minimal}
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\begin{document}$${\text{m}\dot{\text{V}}\text{O}}_{{2}}$$\end{document}mV˙O2 and complexity at 30º was likely due to low relative task demands, given the similar kinetics of \documentclass[12pt]{minimal}
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\begin{document}$${\text{m}\dot{\text{V}}\text{O}}_{{2}}$$\end{document}mV˙O2 and torque complexity. An inverse correlation between \documentclass[12pt]{minimal}
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\begin{document}$${\text{m}\dot{\text{V}}\text{O}}_{{2}}$$\end{document}mV˙O2 and knee-extensor torque complexity occurs during high-intensity contractions at intermediate, but not short, muscle lengths.
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Diniz RCR, Tourino FD, Lacerda LT, Martins-Costa HC, Lanza MB, Lima FV, Chagas MH. Does the Muscle Action Duration Induce Different Regional Muscle Hypertrophy in Matched Resistance Training Protocols? J Strength Cond Res 2020; 36:2371-2380. [DOI: 10.1519/jsc.0000000000003883] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Acute effect of tendon vibration applied during isometric contraction at two knee angles on maximal knee extension force production. PLoS One 2020; 15:e0242324. [PMID: 33186411 PMCID: PMC7665630 DOI: 10.1371/journal.pone.0242324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 11/02/2020] [Indexed: 11/19/2022] Open
Abstract
The aim of the current study was to investigate the effect of a single session of prolonged tendon vibration combined with low submaximal isometric contraction on maximal motor performance. Thirty-two young sedentary adults were assigned into two groups that differed based on the knee angle tested: 90° or 150° (180° = full knee extension). Participants performed two fatigue-inducing exercise protocols: one with three 10 min submaximal (10% of maximal voluntary contraction) knee extensor contractions and patellar tendon vibration (80 Hz) another with submaximal knee extensor contractions only. Before and after each fatigue protocol, maximal voluntary isometric contractions (MVC), voluntary activation level (assessed by the twitch interpolation technique), peak-to-peak amplitude of maximum compound action potentials of vastus medialis and vastus lateralis (assessed by electromyography with the use of electrical nerve stimulation), peak twitch amplitude and peak doublet force were measured. The knee extensor fatigue was significantly (P<0.05) greater in the 90° knee angle group (-20.6% MVC force, P<0.05) than the 150° knee angle group (-8.3% MVC force, P = 0.062). Both peripheral and central alterations could explain the reduction in MVC force at 90° knee angle. However, tendon vibration added to isometric contraction did not exacerbate the reduction in MVC force. These results clearly demonstrate that acute infrapatellar tendon vibration using a commercial apparatus operating at optimal conditions (i.e. contracted and stretched muscle) does not appear to induce knee extensor neuromuscular fatigue in young sedentary subjects.
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Rockenfeller R, Günther M, Stutzig N, Haeufle DFB, Siebert T, Schmitt S, Leichsenring K, Böl M, Götz T. Exhaustion of Skeletal Muscle Fibers Within Seconds: Incorporating Phosphate Kinetics Into a Hill-Type Model. Front Physiol 2020; 11:306. [PMID: 32431619 PMCID: PMC7214688 DOI: 10.3389/fphys.2020.00306] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/19/2020] [Indexed: 12/01/2022] Open
Abstract
Initiated by neural impulses and subsequent calcium release, skeletal muscle fibers contract (actively generate force) as a result of repetitive power strokes of acto-myosin cross-bridges. The energy required for performing these cross-bridge cycles is provided by the hydrolysis of adenosine triphosphate (ATP). The reaction products, adenosine diphosphate (ADP) and inorganic phosphate (P i ), are then used-among other reactants, such as creatine phosphate-to refuel the ATP energy storage. However, similar to yeasts that perish at the hands of their own waste, the hydrolysis reaction products diminish the chemical potential of ATP and thus inhibit the muscle's force generation as their concentration rises. We suggest to use the term "exhaustion" for force reduction (fatigue) that is caused by combined P i and ADP accumulation along with a possible reduction in ATP concentration. On the basis of bio-chemical kinetics, we present a model of muscle fiber exhaustion based on hydrolytic ATP-ADP-P i dynamics, which are assumed to be length- and calcium activity-dependent. Written in terms of differential-algebraic equations, the new sub-model allows to enhance existing Hill-type excitation-contraction models in a straightforward way. Measured time courses of force decay during isometric contractions of rabbit M. gastrocnemius and M. plantaris were employed for model verification, with the finding that our suggested model enhancement proved eminently promising. We discuss implications of our model approach for enhancing muscle models in general, as well as a few aspects regarding the significance of phosphate kinetics as one contributor to muscle fatigue.
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Affiliation(s)
| | - Michael Günther
- Institute for Modelling and Simulation of Biomechanical Systems, Computational Biophysics and Biorobotics, University of Stuttgart, Stuttgart, Germany
- Friedrich-Schiller-University, Jena, Germany
| | - Norman Stutzig
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Daniel F. B. Haeufle
- Hertie-Institute for Clinical Brain Research and Center for Integrative Neuroscience, Eberhard-Karls-University, Tübingen, Germany
| | - Tobias Siebert
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Syn Schmitt
- Institute for Modelling and Simulation of Biomechanical Systems, Computational Biophysics and Biorobotics, University of Stuttgart, Stuttgart, Germany
| | - Kay Leichsenring
- Institute of Solid Mechanics, Technical University Braunschweig, Braunschweig, Germany
| | - Markus Böl
- Institute of Solid Mechanics, Technical University Braunschweig, Braunschweig, Germany
| | - Thomas Götz
- Mathematical Institute, University of Koblenz-Landau, Koblenz, Germany
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Wernbom M, Aagaard P. Muscle fibre activation and fatigue with low-load blood flow restricted resistance exercise-An integrative physiology review. Acta Physiol (Oxf) 2020; 228:e13302. [PMID: 31108025 DOI: 10.1111/apha.13302] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 05/12/2019] [Accepted: 05/17/2019] [Indexed: 12/13/2022]
Abstract
Blood flow-restricted resistance exercise (BFRRE) has been shown to induce increases in muscle size and strength, and continues to generate interest from both clinical and basic research points of view. The low loads employed, typically 20%-50% of the one repetition maximum, make BFRRE an attractive training modality for individuals who may not tolerate high musculoskeletal forces (eg, selected clinical patient groups such as frail old adults and patients recovering from sports injury) and/or for highly trained athletes who have reached a plateau in muscle mass and strength. It has been proposed that achieving a high degree of muscle fibre recruitment is important for inducing muscle hypertrophy with BFRRE, and the available evidence suggest that fatiguing low-load exercise during ischemic conditions can recruit both slow (type I) and fast (type II) muscle fibres. Nevertheless, closer scrutiny reveals that type II fibre activation in BFRRE has to date largely been inferred using indirect methods such as electromyography and magnetic resonance spectroscopy, while only rarely addressed using more direct methods such as measurements of glycogen stores and phosphocreatine levels in muscle fibres. Hence, considerable uncertainity exists about the specific pattern of muscle fibre activation during BFRRE. Therefore, the purpose of this narrative review was (1) to summarize the evidence on muscle fibre recruitment during BFRRE as revealed by various methods employed for determining muscle fibre usage during exercise, and (2) to discuss reported findings in light of the specific advantages and limitations associated with these methods.
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Affiliation(s)
- Mathias Wernbom
- Center for Health and Performance, Department of Food and Nutrition and Sport Science University of Gothenburg Gothenburg Sweden
- Department of Health and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
| | - Per Aagaard
- Department of Sports Sciences and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC) University of Southern Denmark Odense M Denmark
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Effect of knee joint angle on the neuromuscular activation of the quadriceps femoris during repetitive fatiguing contractions. J Electromyogr Kinesiol 2019; 49:102356. [PMID: 31557704 DOI: 10.1016/j.jelekin.2019.102356] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/16/2019] [Accepted: 09/11/2019] [Indexed: 11/22/2022] Open
Abstract
We assessed the effect of knee joint angle on the EMG amplitude and frequency of the four individual muscles in the quadriceps femoris during repetitive fatiguing maximum voluntary contractions (MVCs). Fifteen healthy men and women performed two fatiguing tasks consisting of 40 MVCs in flexion (80°) and extension (140˚) (full extension = 180˚). Neuromuscular activation of the vastus intermedius (VI), vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) was recorded using surface electrodes, and median frequency (MF) and root mean square (RMS) of electromyographic (EMG) signals (normalized by pre-test MVCs) were calculated. MVCs significantly decreased from the 10th to the 40th repetition in both flexion and extension. The MFs of VI and VM in flexion and that of RF flexion and extension were significantly decreased after the 10th repetition. There were no significant changes in normalized EMG amplitude in any muscles specific to knee angle. Stepwise regression analysis suggested that predictive synergistic action may occur in RF/VM and RF/VI in flexion and in RF/VM in extension. This suggest that EMG MF of RF/VM is independent, but that of RF/VI and RF/VL is dependent upon knee joint angle, which may, in part, explain joint angle-specific muscle fatigue.
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12
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Pedersen KK, Madsen MK, Hvid LG, Overgaard K. Concentric strength training at optimal or short muscle length improves strength equally but does not reduce fatigability of hamstring muscles. Physiol Rep 2019; 7:e14196. [PMID: 31423755 PMCID: PMC6698487 DOI: 10.14814/phy2.14196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 07/12/2019] [Indexed: 12/16/2022] Open
Abstract
The purpose of this study was to compare the effect of a 6-week period of knee flexion strength training at either optimal or short muscle length, on length-specific muscle strength and fatigue. Twelve healthy volunteers performed dynamic (isokinetic concentric) training with one leg at short and the contralateral leg at optimal muscle length for 6 weeks. Knee flexor muscle strength was assessed before and after training, comprising maximal voluntary isometric and dynamic contractions at short, intermediate and near optimal muscle length and electrically evoked, contractions at near optimal length only. Fatigability was tested by performing 60 maximal concentric contractions at either short or optimal muscle length. Isometric torque at all muscle lengths improved equally by training at short and optimal muscle length, for example, tested at short 18 (17) versus 21 (17) % (CI) and at optimal 14 (8) versus 17 (16) % muscle length, respectively. Likewise, equal improvements were observed for dynamic contractions in both groups. Prior to training, fatigue induced at optimal muscle length tended to be more pronounced than at short muscle length (fatigue-indexes -41 (6) vs. -34 (7) %, respectively, P = 0.05). However, training at either length did not reduce fatigability. Training with maximal concentric contractions at either short or optimal muscle length for 6 weeks improved isometric and dynamic muscle strength in the entire range of motion without inducing any discernible length-specific adaptations. However, strength training at restricted muscle length did not reduce relative fatigue when induced at either short or optimal muscle length.
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Affiliation(s)
- Katja K. Pedersen
- Department of Public Health, Section of Sport ScienceAarhus UniversityAarhusDenmark
| | - Martin K. Madsen
- Department of Public Health, Section of Sport ScienceAarhus UniversityAarhusDenmark
| | - Lars G. Hvid
- Department of Public Health, Section of Sport ScienceAarhus UniversityAarhusDenmark
| | - Kristian Overgaard
- Department of Public Health, Section of Sport ScienceAarhus UniversityAarhusDenmark
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13
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Ando R, Tomita A, Watanabe K, Akima H. Knee joint angle and vasti muscle electromyograms during fatiguing contractions. Clin Physiol Funct Imaging 2016; 38:566-572. [PMID: 27194453 DOI: 10.1111/cpf.12372] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 04/14/2016] [Indexed: 12/22/2022]
Abstract
We compared vasti muscle electromyograms for two knee joint angles during fatiguing tetanic contractions. Tetanic contraction of the knee extensors was evoked for 70 s by electrical stimulation of the femoral nerve at knee joint angles of 60° (extended, with 0° indicating full extension) and 110° (flexed) in eight healthy men. Surface electromyography was recorded from the vastus intermedius (VI), vastus lateralis (VL) and vastus medialis (VM) muscles. Knee extension force and M-wave amplitudes and durations were calculated every 7 s, which were normalized by the initial value. Normalized knee extension force was decreased at the flexed knee joint angle compared with that of the extended knee joint angle (P<0·05). Decreased normalized M-wave amplitude and increased normalized M-wave duration of the VI were greater at the flexed knee joint angle than the extended knee joint angle (P<0·05), whereas those for the VL and VM were similar (P>0·05). These results suggest that peripheral fatigue profiles of the VI might be greater at the flexed than the extended knee joint angles, but that of VL and VM might be similar in the tested range of knee joint angles (i.e. 60°-110°) during continuous tetanic contraction induced by electrical stimulation. Therefore, greater reduction of knee extension force at the flexed knee joint angle than the extended knee joint angle may reflect fatigue development of the VI more than other quadriceps femoris components.
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Affiliation(s)
- Ryosuke Ando
- Graduate School of Education and Human Development, Nagoya University, Nagoya, Japan.,Japan Society for the Promotion of Science, Nagoya, Japan
| | - Aya Tomita
- Graduate School of Education and Human Development, Nagoya University, Nagoya, Japan
| | - Kohei Watanabe
- School of International Liberal Studies, Chukyo University, Nagoya, Japan
| | - Hiroshi Akima
- Graduate School of Education and Human Development, Nagoya University, Nagoya, Japan.,Research Center of Health, Physical Fitness & Sports, Nagoya University, Nagoya, Japan
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14
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Bernecke V, Pukenas K, Imbrasiene D, Mickeviciene D, Baranauskiene N, Eimantas N, Brazaitis M. Test-Retest Cross-Reliability of Tests to Assess Neuromuscular Function as a Multidimensional Concept. J Strength Cond Res 2016; 29:1972-84. [PMID: 25635607 DOI: 10.1519/jsc.0000000000000841] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The purpose of this investigation was to estimate the test-retest cross-reliability of peripheral and central changes with respect to nonlinear and linear measures of a surface electromyography (EMG) signal measured during isometric maximal voluntary contraction (MVC) combined with superimposed electrical stimulation during a brief and fatiguing task involving the ankle plantar flexors over 2 follicular phases of menstrual cycle. Ten healthy female adults underwent 1 familiarization session and 5 identical test-retest sessions. The results showed that the decrease in plantar flexor EMG components (root mean square [RMS], mean frequency [MnF], wavelet packet entropy [WPE]) for soleus and gastrocnemius muscles, central activation ratio (CAR) and MVC, and contractile properties (P20, P100, PTT-100, and half-relaxation time) of the plantar flexor muscles at the end of 2-minute MVC were similar (time effect; p < 0.001, η(p)² > 0.7, statistical power [SP] > 99%) and exhibited high stability over 5 trials (trial effect; p > 0.05; η(p)² < 0.2, SP < 30%). High reliability between trials was found for 5-second MVC (intraclass correlation coefficient [ICC] > 0.82, p < 0.001) and meaningful reliability for 2-minute MVC (ICC > 0.66, p < 0.01). In conclusion, in young healthy women, measurements of neuromuscular function, such as RMS, MnF, and WPE of a surface EMG signal, MVC, and CAR from a brief and sustained MVC of the ankle plantar flexors, are reliable, and multidimensional stability was found with respect to both high and low correlation outcomes across the 5 identical test-retest trials of any 2 properties measured during brief and sustained MVC.
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Affiliation(s)
- Vaida Bernecke
- 1Sports Science and Innovation Institute, Lithuanian Sports University, Kaunas, Lithuania; and 2Department of Rehabilitation, Siauliai State College, Siauliai, Lithuania
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15
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Noorkõiv M, Nosaka K, Blazevich AJ. Neuromuscular adaptations associated with knee joint angle-specific force change. Med Sci Sports Exerc 2015; 46:1525-37. [PMID: 24504427 DOI: 10.1249/mss.0000000000000269] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Neuromuscular adaptations to joint angle-specific force increases after isometric training have not yet been fully elucidated. This study examined angle-specific neuromuscular adaptations in response to isometric knee extension training at short (SL, joint angle 38.1° ± 3.7°) versus long (LL, 87.5° ± 6.0°) muscle lengths. METHODS Sixteen men trained three times a week for 6 wk either at SL (n = 8) or LL (n = 8). Voluntary maximal isometric knee extensor (MVC) force, doublet twitch force, EMG amplitudes (EMG/Mmax), and voluntary activation during MVC force (VA%) were measured at eight knee joint angles (30°-100°) at weeks 0, 3, and 6. Muscle volume and cross-sectional area (CSA) were measured from magnetic resonance imaging scans, and fascicle length (Lf) was assessed using ultrasonography before and after training. RESULTS Clear joint angle specificity of force increase was seen in SL but not in LL. The 13.4% ± 9.7% (P = 0.01) force increase around the training angle in SL was related to changes in vastus lateralis and vastus medialis EMG/Mmax around the training angle (r = 0.84-0.88, P < 0.05), without changes in the doublet twitch force-angle relation or muscle size. In LL, muscle volume and CSA increased and the changes in CSA at specific muscle regions were correlated with changes in MVC force. A 5.4% ± 4.9% (P = 0.001) increase in Lf found in both groups was not associated with angle-specific force changes. There were no angle-specific changes in VA%. CONCLUSION The EMG/Mmax, although not VA%, results suggest that neural adaptations underpinned training-related changes at short quadriceps lengths, but hypertrophic changes predominated after training at long lengths. The findings of this study should contribute to the development of more effective and evidence-based rehabilitation and strength training protocols.
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Affiliation(s)
- Marika Noorkõiv
- School of Exercise and Health Sciences, Centre for Exercise and Sports Science Research, Edith Cowan University, Joondalup, AUSTRALIA
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16
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Hug F, Hodges PW, Hoorn WVD, Tucker K. Between-muscle differences in the adaptation to experimental pain. J Appl Physiol (1985) 2014; 117:1132-40. [DOI: 10.1152/japplphysiol.00561.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
This study aimed to determine whether muscle stress (force per unit area) can be redistributed between individual heads of the quadriceps muscle when pain is induced into one of these heads. Elastography was used to measure muscle shear elastic modulus (an index of muscle stress). Electromyography (EMG) was recorded from vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF). In experiment I ( n = 20), participants matched a knee extension force, and thus any reduction of stress within the painful muscle would require compensation by other muscles. In experiment II ( n = 13), participants matched VL EMG amplitude and were free to vary external force such that intermuscle compensation would be unnecessary to maintain the experimental task. In experiments I and II, pain was induced by injection of hypertonic saline into VM or RF. Experiment III aimed to establish whether voluntary drive to the individual muscles could be controlled independently. Participants ( n = 13) were asked to voluntarily reduce activation of VM or RF while maintaining knee extension force. During VM pain, there was no change in shear elastic modulus ( experiments I and II) or EMG amplitude of VM ( experiment II). In contrast, RF pain was associated with a reduction in RF elastic modulus ( experiments I and II: −8 to −17%) and EMG amplitude ( experiment II). Participants could voluntarily reduce EMG amplitude of RF ( −26%; P = 0.003 ) but not VM ( experiment III). These results highlight between-muscle differences in adaptation to pain that might be explained by their function (monoarticular vs. biarticular) and/or the neurophysiological constraints associated to their activation.
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Affiliation(s)
- François Hug
- The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, Brisbane, Australia
- University of Nantes, Laboratory “Motricité, Interactions, Performance” (EA 4334), UFR STAPS, F-44000, Nantes, France; and
| | - Paul W. Hodges
- The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, Brisbane, Australia
| | - Wolbert van den Hoorn
- The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, Brisbane, Australia
| | - Kylie Tucker
- The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, Brisbane, Australia
- The University of Queensland, School of Biomedical Sciences, Brisbane, Australia
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17
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Beneficial effects of serial contractions on muscle performance after a brief period of rest. Eur J Appl Physiol 2014; 114:1657-65. [DOI: 10.1007/s00421-014-2896-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 04/16/2014] [Indexed: 10/25/2022]
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18
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Green LA, Parro JJ, Gabriel DA. Quantifying the familiarization period for maximal resistive exercise. Appl Physiol Nutr Metab 2014; 39:275-81. [DOI: 10.1139/apnm-2013-0253] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Resistive exercise is used in the assessment of musculoskeletal health, performance, training interventions, and population differences (i.e., gender, age, training status). There is a need to determine the amount of familiarization required to stabilize performance prior to testing. Fifteen males completed a familiarization session consisting of 3 blocks of 5 maximal isometric dorsiflexion contractions, followed by a retention test (an additional block of 5 contractions) performed 3 days later. Mean force and surface electromyography (sEMG) from both the agonist and antagonist muscles were collected. A variance ratio, representing the stability between trials, was calculated for each of the 4 blocks of 5 contractions for both force and sEMG. The variance ratio for both force and agonist sEMG decreased significantly within the first 10 trials and remained stable during the retention test. The variance ratio for antagonist sEMG was stable across the 3 blocks of familiarization and significantly decreased during the retention test. The magnitude variables all remained stable across the 3 familiarization blocks. However, an 11% increase in mean force was seen during the retention test while both agonist and antagonist sEMG remained stable. Although slight changes occurred in the magnitude variables during the retention test, the stabilization of the force and agonist sEMG variance ratios suggest that familiarization to the task was achieved within the first 10 contractions and was sustained over a 3-day period.
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Affiliation(s)
- Lara A. Green
- Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Justin J. Parro
- Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - David A. Gabriel
- Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
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19
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Effect of Caffeine on Fatigue During Submaximal Isometric Contractions at Different Knee Angles. ACTA ACUST UNITED AC 2011. [DOI: 10.2478/v10036-011-0027-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Tomaras EK, MacIntosh BR. Less is more: standard warm-up causes fatigue and less warm-up permits greater cycling power output. J Appl Physiol (1985) 2011; 111:228-35. [PMID: 21551012 DOI: 10.1152/japplphysiol.00253.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The traditional warm-up (WU) used by athletes to prepare for a sprint track cycling event involves a general WU followed by a series of brief sprints lasting ≥ 50 min in total. A WU of this duration and intensity could cause significant fatigue and impair subsequent performance. The purpose of this research was to compare a traditional WU with an experimental WU and examine the consequences of traditional and experimental WU on the 30-s Wingate test and electrically elicited twitch contractions. The traditional WU began with 20 min of cycling with a gradual intensity increase from 60% to 95% of maximal heart rate; then four sprints were performed at 8-min intervals. The experimental WU was shorter with less high-intensity exercise: intensity increased from 60% to 70% of maximal heart rate over 15 min; then just one sprint was performed. The Wingate test was conducted with a 1-min lead-in at 80% of optimal cadence followed by a Wingate test at optimal cadence. Peak active twitch torque was significantly lower after the traditional than experimental WU (86.5 ± 3.3% vs. 94.6 ± 2.4%, P < 0.05) when expressed as percentage of pre-WU amplitude. Wingate test performance was significantly better (P < 0.01) after experimental WU (peak power output = 1,390 ± 80 W, work = 29.1 ± 1.2 kJ) than traditional WU (peak power output = 1,303 ± 89 W, work = 27.7 ± 1.2 kJ). The traditional track cyclist's WU results in significant fatigue, which corresponds with impaired peak power output. A shorter and lower-intensity WU permits a better performance.
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Affiliation(s)
- Elias K Tomaras
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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21
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Changes in muscle contractile characteristics and jump height following 24 days of unilateral lower limb suspension. Eur J Appl Physiol 2011; 112:135-44. [PMID: 21505844 PMCID: PMC3253280 DOI: 10.1007/s00421-011-1958-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 04/01/2011] [Indexed: 11/16/2022]
Abstract
We measured changes in maximal voluntary and electrically evoked torque and rate of torque development because of limb unloading. We investigated whether these changes during single joint isometric muscle contractions were related to changes in jump performance involving dynamic muscle contractions and several joints. Six healthy male subjects (21 ± 1 years) underwent 3 weeks of unilateral lower limb suspension (ULLS) of the right limb. Plantar flexor and knee extensor maximal voluntary contraction (MVC) torque and maximal rate of torque development (MRTD), voluntary activation, and maximal triplet torque (thigh; 3 pulses at 300 Hz) were measured next to squat jump height before and after ULLS. MVC of plantar flexors and knee extensors (MVCke) and triplet torque decreased by 12% (P = 0.012), 21% (P = 0.001) and 11% (P = 0.016), respectively. Voluntary activation did not change (P = 0.192). Absolute MRTD during voluntary contractions decreased for plantar flexors (by 17%, P = 0.027) but not for knee extensors (P = 0.154). Absolute triplet MRTD decreased by 17% (P = 0.048). The reduction in MRTD disappeared following normalization to MVC. Jump height with the previously unloaded leg decreased significantly by 28%. No significant relationships were found between any muscle variable and jump height (r < 0.48), but decreases in torque were (triplet, r = 0.83, P = 0.04) or tended to be (MVCke r = 0.71, P = 0.11) related to decreases in jump height. Thus, reductions in isometric muscle torque following 3 weeks of limb unloading were significantly related to decreases in the more complex jump task, although torque in itself (without intervention) was not related to jump performance.
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22
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Influence of exercise intensity and joint angle on endurance time prediction of sustained submaximal isometric knee extensions. Eur J Appl Physiol 2010; 111:1187-96. [DOI: 10.1007/s00421-010-1731-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2010] [Indexed: 10/18/2022]
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Horstman AM, Gerrits KH, Beltman MJ, Koppe PA, Janssen TW, de Haan A. Intrinsic properties of the knee extensor muscles after subacute stroke. Arch Phys Med Rehabil 2010; 91:123-8. [PMID: 20103406 DOI: 10.1016/j.apmr.2009.09.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 08/31/2009] [Accepted: 09/02/2009] [Indexed: 11/17/2022]
Abstract
UNLABELLED Horstman AM, Gerrits KH, Beltman MJ, Koppe PA, Janssen, TW, de Haan A. Intrinsic properties of the knee extensor muscles after subacute stroke. OBJECTIVE To characterize muscle properties of paretic lower-limb (PL) and nonparetic lower-limb (NL) knee extensors in patients with subacute stroke. DESIGN Case-control study. SETTING Rehabilitation center research laboratory. PARTICIPANTS Patients with subacute stroke (n=14) and able-bodied age-matched control subjects (n=12). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Half relaxation times (HRTs) and maximal rates of torque development (MRTDs) were assessed as indicators of contractile speed using both voluntary and electrically evoked contractions. Moreover, changes in torque were measured during a fatigue protocol (35 electrically evoked intermittent contractions; 1.5s on, 2s off) and recovery. RESULTS No differences among groups were found for normalized MRTDs during electrically evoked contractions (P=.117). However, during voluntary contractions both PLs (53% of control, P=.022) and NL (71% of control, P<.001) had significantly lower MRTD compared with control. Both PL (134% of control, P=.001) and NL (123% of control, P=.032) had significantly higher HRTs than control, indicating muscle slowing in patients with subacute stroke. PLs fatigued more and faster than control (P=.011) and both PL and NL recovered slower (P<.001). CONCLUSIONS The changes in HRTs and fatigue suggest adaptations in muscle properties toward slower, more fatigable muscle shortly after stroke. The inability to make use of contractile speed because of impaired neural activation seems the most limiting factor during the initial phase of torque development in PL. Thus, besides strengthening, muscle endurance and speed should also be addressed during rehabilitation.
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Affiliation(s)
- Astrid M Horstman
- Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands.
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24
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The influence of muscle length on the fatigue-related reduction in joint range of motion of the human dorsiflexors. Eur J Appl Physiol 2010; 109:405-15. [DOI: 10.1007/s00421-010-1364-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2010] [Indexed: 10/19/2022]
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25
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Place N, Bruton JD, Westerblad H. MECHANISMS OF FATIGUE INDUCED BY ISOMETRIC CONTRACTIONS IN EXERCISING HUMANS AND IN MOUSE ISOLATED SINGLE MUSCLE FIBRES. Clin Exp Pharmacol Physiol 2009; 36:334-9. [PMID: 18671711 DOI: 10.1111/j.1440-1681.2008.05021.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nicolas Place
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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26
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Altenburg TM, de Ruiter CJ, Verdijk PW, van Mechelen W, de Haan A. Vastus lateralis surface and single motor unit EMG following submaximal shortening and lengthening contractions. Appl Physiol Nutr Metab 2008; 33:1086-95. [DOI: 10.1139/h08-092] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A single shortening contraction reduces the force capacity of muscle fibers, whereas force capacity is enhanced following lengthening. However, how motor unit recruitment and discharge rate (muscle activation) are adapted to such changes in force capacity during submaximal contractions remains unknown. Additionally, there is limited evidence for force enhancement in larger muscles. We therefore investigated lengthening- and shortening-induced changes in activation of the knee extensors. We hypothesized that when the same submaximal torque had to be generated following shortening, muscle activation had to be increased, whereas a lower activation would suffice to produce the same torque following lengthening. Muscle activation following shortening and lengthening (20° at 10°/s) was determined using rectified surface electromyography (rsEMG) in a 1st session (at 10% and 50% maximal voluntary contraction (MVC)) and additionally with EMG of 42 vastus lateralis motor units recorded in a 2nd session (at 4%–47%MVC). rsEMG and motor unit discharge rates following shortening and lengthening were normalized to isometric reference contractions. As expected, normalized rsEMG (1.15 ± 0.19) and discharge rate (1.11 ± 0.09) were higher following shortening (p < 0.05). Following lengthening, normalized rsEMG (0.91 ± 0.10) was, as expected, lower than 1.0 (p < 0.05), but normalized discharge rate (0.99 ± 0.08) was not (p > 0.05). Thus, muscle activation was increased to compensate for a reduced force capacity following shortening by increasing the discharge rate of the active motor units (rate coding). In contrast, following lengthening, rsEMG decreased while the discharge rates of active motor units remained similar, suggesting that derecruitment of units might have occurred.
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Affiliation(s)
- Teatske M. Altenburg
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Cheshire, UK
- Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, the Netherlands
- EMGO Institute and Department of Public and Occupational Health, VU University Medical Centre, Amsterdam, the Netherlands
| | - Cornelis J. de Ruiter
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Cheshire, UK
- Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, the Netherlands
- EMGO Institute and Department of Public and Occupational Health, VU University Medical Centre, Amsterdam, the Netherlands
| | - Peter W.L. Verdijk
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Cheshire, UK
- Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, the Netherlands
- EMGO Institute and Department of Public and Occupational Health, VU University Medical Centre, Amsterdam, the Netherlands
| | - Willem van Mechelen
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Cheshire, UK
- Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, the Netherlands
- EMGO Institute and Department of Public and Occupational Health, VU University Medical Centre, Amsterdam, the Netherlands
| | - Arnold de Haan
- Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Cheshire, UK
- Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, the Netherlands
- EMGO Institute and Department of Public and Occupational Health, VU University Medical Centre, Amsterdam, the Netherlands
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27
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de Ruiter CJ, Hoddenbach JG, Huurnink A, de Haan A. Relative torque contribution of vastus medialis muscle at different knee angles. Acta Physiol (Oxf) 2008; 194:223-37. [PMID: 18691348 DOI: 10.1111/j.1748-1716.2008.01888.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM We investigated the relative contribution of the vastus medialis (VM) muscle to total isometric knee extension torque at 10 degrees , 30 degrees , 60 degrees and 90 degrees knee flexion. In the past a more prominent role of the VM muscle at more extended knee angles has been put forward. However, different components of the quadriceps muscle converge via a common distal tendon. We therefore hypothesized that the relative contribution of the VM to total knee extension torque would be similar across angles. METHODS At each knee angle the EMG isometric torque relations [20%, 25%, 30%, 35% maximal voluntary contraction (MVC)] of the rectus femoris (RF), vastus lateralis (VL) and VM muscle were established in 10 healthy male subjects; rectified surface EMG was normalized to M-wave area. Subsequently, the VM was functionally eliminated by selective electrical surface stimulation with occluded blood flow. RESULTS There was no evidence for preferential activation of VM at any of the knee angles. Following VM elimination, total knee extension torque during maximal femoral nerve stimulation (three pulses at 300 Hz) at 10 degrees , 30 degrees , 60 degrees and 90 degrees , respectively, decreased (P < 0.05) to (mean +/- SD): 75.7 +/- 12.2, 75.1 +/- 9.3, 78.2 +/- 7.2 and 76.0 +/- 5.8% (P > 0.05 among knee angles). In addition, during voluntary contractions at 20% MVC the increases in torque output of RF and VL compensating for the loss of VM function were calculated from the increases in EMG and found to be similar (P > 0.05) at 10 degrees , 30 degrees , 60 degrees and 90 degrees values (%MVC), respectively, were: 9.1 +/- 6.8, 7.5 +/- 2.9, 5.9 +/- 3.7 and 6.9 +/- 3.4. CONCLUSION The present findings support our hypothesis that the VM contributes similarly to total knee extension torque at different knee angles.
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Affiliation(s)
- C J de Ruiter
- Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam, the Netherlands. c_ j
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Millet GY, Aubert D, Favier FB, Busso T, Benoît H. Effect of acute hypoxia on central fatigue during repeated isometric leg contractions. Scand J Med Sci Sports 2008; 19:695-702. [PMID: 18627554 DOI: 10.1111/j.1600-0838.2008.00823.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To determine whether hypoxia has a direct influence on the central command independently of the working muscles, 16 subjects performed intermittent isometric unilateral knee extensions until exhaustion either in normobaric hypoxia (inspired O(2) fraction=0.11, arterial oxygen saturation approximately 84%) or in normoxia while the knee extensor muscles were exposed to circulatory occlusion with a 250 mmHg cuff. Among the subjects, 11 also performed the tests in hypoxia and normoxia without occlusion. Single electrical stimulations were regularly delivered to the femoral nerve to measure the changes in the knee extensor peak twitch force. With the cuff, the average slope of decrease in peak twitch did not depend on the inspired oxygen fraction. Performance was slightly but significantly lower during hypoxia than in normoxia (8.2+/-2.6 vs 9.4+/-3.1 repetitions, P<0.05) with the cuff on. The number of repetitions was much higher during hypoxia with maintaining leg blood flow (15.6+/-4.5 repetitions) than with circulatory occlusion in normoxia. In conclusion, this study showed that a direct effect of hypoxia in reducing the motor drive to the working muscles exists but this effect is moderate.
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Affiliation(s)
- G Y Millet
- Unité PPEH-Médecine du Sport-Myologie, Hôpital Bellevue, Saint-Etienne, France.
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Horstman AM, Beltman MJ, Gerrits KH, Koppe P, Janssen TW, Elich P, de Haan A. Intrinsic muscle strength and voluntary activation of both lower limbs and functional performance after stroke. Clin Physiol Funct Imaging 2008; 28:251-61. [PMID: 18355344 DOI: 10.1111/j.1475-097x.2008.00802.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The objective of this study was to assess the nature of muscle weakness in both legs after stroke compared with able-bodied control individuals and to examine whether there is a relationship between the degree of muscle weakness and coactivation of knee extensors and flexors as well as voluntary activation capacity of knee extensors of both paretic and non-paretic legs and indices of functional performance. Maximal voluntary isometric torques of knee extensors (MVCe) and flexors (MVCf) were determined in 14 patients (bilaterally) and 12 able-bodied controls. Simultaneous measurements were made of torque and surface EMG from agonist and antagonist muscles. Coactivation was calculated. Supramaximal triplets were evoked with electrical stimulation to estimate maximal torque capacity and degree of voluntary activation of knee extensors. MVCs, activation and coactivation parameters were correlated to scores of seven functional performance tests. MVCe, MVCf and voluntary activation were lower in paretic lower limb (PL) compared with both non-paretic lower limb (NL) and control. Besides, all these parameters of NL were also lower than control. Electrically evoked torque capacity of knee extensors of PL was about 60% of both NL and control, which were not significantly different from each other. Strong significant correlations between strength, as well as voluntary activation, and functional performance were found. Coactivation did not correlate well with functional performance. Thus, whereas for NL activation failure can explain weakness, for PL both activation failure and reduced intrinsic torque capacity are responsible for the severe weakness. Activation capacity and muscle strength correlated strongly to functional performance, while coactivation did not.
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Affiliation(s)
- Astrid M Horstman
- Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands.
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Pietrosimone BG, Hammill RR, Saliba EN, Hertel J, Ingersoll CD. Joint angle and contraction mode influence quadriceps motor neuron pool excitability. Am J Phys Med Rehabil 2008; 87:100-8. [PMID: 17912136 DOI: 10.1097/phm.0b013e31815882e0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The purpose of the study was to compare the central activation ratio (CAR) of eccentric contractions to isometric contractions at 30 and 70 degrees of knee flexion. DESIGN A repeated-measures design was used. CARs were measured at 30 and 70 degrees of knee flexion in 16 healthy subjects during both eccentric and isometric modes of contraction. CARs were measured using the superimposed burst technique. RESULTS Isometric CARs at 30 degrees (0.88+/-0.069) of knee flexion were significantly higher (P<0.001) than at 70 degrees (0.77+/-0.116). Eccentric CARs were significantly higher (P=0.013) at 70 degrees (0.87+/-0.085) of knee flexion compared with 30 degrees (0.8+/-0.09). At 30 degrees of knee flexion, isometric CARs were significantly higher (P=0.003) than eccentric CARs. At 70 degrees, eccentric CARs were higher (P<0.001) when compared with isometric CARs. CONCLUSIONS Our results provide evidence that isometric measures at a single joint angle are not sufficient in generalizing activation of an entire muscle group for dynamic movements. CARs are significantly affected by joint angle and mode of contraction.
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Affiliation(s)
- Brian G Pietrosimone
- Exercise & Sport Injury Laboratory, University of Virginia, Charlottesville, Virginia, USA
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31
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Effect of voluntary activation on age-related muscle fatigue resistance. J Biomech 2008; 41:1229-35. [DOI: 10.1016/j.jbiomech.2008.01.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 01/18/2008] [Accepted: 01/24/2008] [Indexed: 11/24/2022]
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Knee angle-dependent oxygen consumption of human quadriceps muscles during maximal voluntary and electrically evoked contractions. Eur J Appl Physiol 2007; 102:233-42. [DOI: 10.1007/s00421-007-0573-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2007] [Indexed: 11/25/2022]
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Gerrits K, Pauw-Gommans I, van Engelen B, de Haan A. Contractile properties of knee-extensors in one single family with nemaline myopathy: central and peripheral aspects of muscle activation. Clin Physiol Funct Imaging 2007; 27:217-24. [PMID: 17564670 DOI: 10.1111/j.1475-097x.2007.00740.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Patients with nemaline myopathy, a muscle disorder primarily affecting the thin filaments, suffer from weakness which is poorly understood. As disturbed excitation-contraction coupling has been suggested as a possible mechanism, the present study was designed to investigate whether the contractile properties of the knee-extensor muscles in patients from a single family with nemaline myopathy were different from able-bodied individuals. To assess central neural as well as more peripheral intrinsic aspects of muscle activation, isometric voluntary and electrically elicited quadriceps contractions were evoked at different knee angles. Interestingly, across the range of 30-70 degrees of knee flexion, the capacity to achieve maximal voluntary activation of the muscles, assessed by a super-imposed stimulation technique, was significantly higher in patients compared with controls. Furthermore, the torque-frequency relation differed between groups, with the muscles of patients producing higher torques at low (twitch and 10 Hz) stimulation frequencies relative to maximal (150 Hz) stimulation than controls at both 30 degrees and 60 degrees of knee flexion. These results suggest that no impairment was present at relatively low activation frequencies. It may, however, be indicative for a reduced cross-bridge attachment as part of the excitation-contraction coupling specifically at high activation frequencies. In conclusion, the quadriceps weakness observed in this specific patient group cannot be explained by an impaired capacity to maximally activate these muscles. However, the data of relatively high torques produced at submaximal activation frequencies are compatible with the hypothesis that patients with nemaline myopathy may have an impaired acto-myosin interaction specifically at high levels of activation.
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Affiliation(s)
- Karin Gerrits
- Institute for Fundamental and Clinical Human Movement Sciences, Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands.
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Rudroff T, Christou EA, Poston B, Bojsen-Møller J, Enoka RM. Time to failure of a sustained contraction is predicted by target torque and initial electromyographic bursts in elbow flexor muscles. Muscle Nerve 2007; 35:657-66. [PMID: 17294440 DOI: 10.1002/mus.20752] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The purpose of the study was to identify factors that could predict differences among individuals in the time to failure of a submaximal contraction. Twenty subjects (10 men, 25+/-6 years) supported an inertial load equivalent to 20% of the maximal voluntary contraction (MVC) force with the elbow flexor muscles for as long as possible. The time to failure was predicted by the frequency of electromyographic bursts in the long head of biceps brachii during the first 20% of the contraction, the amplitude of bursts in the brachioradialis during the first 20% of the contraction, and the target torque. Subjects who could sustain the task longer exhibited greater initial (first 20% of contraction) electromyographic burst frequency in the long head of biceps brachii, lower initial burst amplitudes in the brachioradialis muscle, and lower target torque. Knowing the main predictors of a submaximal fatiguing contraction with the elbow flexor muscles may assist clinicians in personalizing therapeutic interventions.
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Affiliation(s)
- Thorsten Rudroff
- Department of Integrative Physiology, University of Colorado, Carlson 202G, 354 UCB, Boulder, Colorado 80309-0354, USA.
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Kooistra RD, de Ruiter CJ, de Haan A. Conventionally assessed voluntary activation does not represent relative voluntary torque production. Eur J Appl Physiol 2007; 100:309-20. [PMID: 17357793 PMCID: PMC1914240 DOI: 10.1007/s00421-007-0425-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2007] [Indexed: 11/25/2022]
Abstract
The ability to voluntarily activate a muscle is commonly assessed by some variant of the twitch interpolation technique (ITT), which assumes that the stimulated force increment decreases linearly as voluntary force increases. In the present study, subjects (n = 7) with exceptional ability for maximal voluntary activation (VA) of the knee extensors were used to study the relationship between superimposed and voluntary torque. This includes very high contraction intensities (90-100%VA), which are difficult to consistently obtain in regular healthy subjects (VA of approximately 90%). Subjects were tested at 30, 60, and 90 degrees knee angles on two experimental days. At each angle, isometric knee extensions were performed with supramaximal superimposed nerve stimulation (triplet: three pulses at 300 Hz). Surface EMG signals were obtained from rectus femoris, vastus lateralis, and medialis muscles. Maximal VA was similar and very high across knee angles: 97 +/- 2.3% (mean +/- SD). At high contraction intensities, the increase in voluntary torque was far greater than would be expected based on the decrement of superimposed torque. When voluntary torque increased from 79.6 +/- 6.1 to 100%MVC, superimposed torque decreased from 8.5 +/- 2.6 to 2.8 +/- 2.3% of resting triplet. Therefore, an increase in VA of 5.7% (from 91.5 +/- 2.6 to 97 +/- 2.3%) coincided with a much larger increase in voluntary torque (20.4 +/- 6.1%MVC) and EMG (33.9 +/- 6.6%max). Moreover, a conventionally assessed VA of 91.5 +/- 2.6% represented a voluntary torque of only 79.6 +/- 6.1%MVC. In conclusion, when maximal VA is calculated to be approximately 90% (as in regular healthy subjects), this probably represents a considerable overestimation of the subjects' ability to maximally drive their quadriceps muscles.
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Affiliation(s)
- R. D. Kooistra
- Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands
| | - C. J. de Ruiter
- Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands
| | - A. de Haan
- Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands
- Institute for Biophysical and Clinical Research into Human Movement, Manchester Metropolitan University, Cheshire, UK
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MacNaughton MB, MacIntosh BR. Impact of length during repetitive contractions on fatigue in rat skeletal muscle. Pflugers Arch 2007; 455:359-66. [PMID: 17473930 DOI: 10.1007/s00424-007-0273-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Accepted: 04/12/2007] [Indexed: 11/27/2022]
Abstract
The magnitude of fatigue resulting from repeated contractions at a short length has been reported to be less than that which occurs with contractions at a long length. However, there have been what appear to be contradictory reports; the rate of fatigue is greater at a short length. The purpose of this study was to evaluate the impact of length on the magnitude and the rate of fatigue resulting from a series of repetitive stimulations. Experiments were done with anesthetized rats and the medial gastrocnemius muscle was stimulated via the sciatic nerve. Submaximal force-length relationships were obtained prior to and 45 min after repeated contractions (50 Hz, 300 ms) at short or long length. Stimulation was applied at 1 Hz or 0.5 Hz for 5 min at the long length or 1 Hz at the short length (difference = 3.6mm). This approach permitted evaluation of the impact of rate of muscle activation as well as length on subsequent contractile response. Repetitive stimulation at a short length resulted in more potentiation and a greater (relative) rate of fatigue but after 5 min the depression of relative active force was similar between the series at long and short length. The submaximal force-length relationship obtained after 45 min of recovery revealed that depression of force was greater after 1 Hz contractions at the long length. These results are consistent with both sides of the apparent contradiction in the literature; rate of fatigue is greater at a short length and magnitude of fatigue is greater at a long length.
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Place N, Maffiuletti NA, Martin A, Lepers R. Assessment of the reliability of central and peripheral fatigue after sustained maximal voluntary contraction of the quadriceps muscle. Muscle Nerve 2007; 35:486-95. [PMID: 17221875 DOI: 10.1002/mus.20714] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The aim of the present study was to further confirm the validity of measurements for characterizing neuromuscular alterations by establishing their reliability both before and after fatigue. Thirteen men (28 +/- 5 years) volunteered to participate in two separate identical sessions requiring the performance of a sustained maximal voluntary contraction (MVC) with the quadriceps muscle for 2 min. MVC and transcutaneous electrical stimulations were used before and immediately after the fatiguing contraction to investigate the reliability of MVC torque, central activation, and peripheral variables (M-wave properties, peak twitch, peak doublet) within and between sessions. Based on previous and present results, we advise the use of (1) voluntary activation level with potentiated doublet as a reference to describe central fatigue, (2) electromyographic activity of vastus lateralis muscle as a surrogate for quadriceps for both voluntary and evoked contraction, and (3) potentiated peak doublet amplitude to investigate contractile fatigue. These findings can be useful in the choice of the parameters describing central and peripheral fatigue of the quadriceps muscle in future studies.
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Affiliation(s)
- Nicolas Place
- INSERM ERM 207 Motricité Plasticité, Faculté des Sciences du Sport, Université de Bourgogne, BP 27877, 21078 Dijon, France.
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38
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Kooistra RD, Blaauboer ME, Born JR, de Ruiter CJ, de Haan A. Knee extensor muscle oxygen consumption in relation to muscle activation. Eur J Appl Physiol 2006; 98:535-45. [PMID: 17089159 DOI: 10.1007/s00421-006-0298-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2006] [Indexed: 10/24/2022]
Abstract
Recently, fatigability and muscle oxygen consumption (mVO(2)) during sustained isometric contractions were found to be less at shorter (30 degrees knee angle; 0 degrees = full extension) compared to longer knee extensor muscle lengths (90 degrees ) and, at low torques, less in the rectus femoris (RF) muscle than in the vastus lateralis and medialis. In the present study we hypothesized that these findings could be accounted for by a knee angle- and a muscle-dependent activation respectively. On two experimental days rectified surface EMG (rsEMG) was obtained as a measure of muscle activation in nine healthy young males. In addition, on day 1 maximal torque capacity (MTC) was carefully determined using superimposed nerve stimulation on brief high intensity contractions (> 70%MVC) at 30, 60 and 90 degrees knee angles. On day 2, subjects performed longer lasting isometric contractions (10-70%MTC) while mVO(2) was measured using near-infrared spectroscopy (NIRS). At 30 degrees , maximal mVO(2) was reached significantly later (11.0 s +/- 6.5 s) and was 57.9 +/- 8.3% less (average +/- SD, across intensities and muscles) than mVO(2) at 60 and 90 degrees (p < 0.05). However, rsEMG was on average only 18.0 +/- 11.8% (p = 0.062) less at the start of the contraction at 30 degrees . At 10%MTC at all knee angles, maximal mVO(2) of the RF occurred significantly later (28.8 +/- 36.0 s) and showed a significantly smaller increase in rsEMG compared to both vasti. In conclusion, it is unlikely that the tendency for less intense muscle activation could fully account for the approximately 60% lower oxygen consumption at 30 degrees , but the later increase in RFmVO(2) seemed to be caused by a less strong activation of the RF.
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Affiliation(s)
- R D Kooistra
- Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081, BT, Amsterdam, The Netherlands.
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39
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Yu NY, Lee HY, Chen JJJ, Chang SH. Measurement and modeling of stimulus-evoked electromyography in lengthened and shortened muscles for spinal cord injured subjects during an electrically-elicited fatigue process. Physiol Meas 2006; 27:1329-43. [PMID: 17135703 DOI: 10.1088/0967-3334/27/12/006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study compares the amplitude and temporal features of stimulus-evoked electromyography (EMG) of paralyzed muscle, rectus femoris (RF), in both lengthened and shortened positions of six spinal cord injured (SCI) subjects during an electrically elicited fatigue process. The torque output and evoked EMG were fitted by hyperbolic tangent functions from which their amplitude residual levels and temporal inflection times can be extracted. Furthermore, a structural EMG model of Fuglevand et al (1992 Biol. Cybern. 67 143-53) was modified to include type I (slow twitch) and type II (fast twitch) of motor unit (MU) fibers with viable parameters obtained from paralyzed muscles to observe their amplitude and temporal changes. Our results showed that the amplitude of stimulus-evoked EMG decreased earlier in the lengthened muscle with a shorter inflection time (48.53 +/- 8.7 s versus 55.13 +/- 4.03 s) than that of the shortened position during 120 s of stimulation time (p < 0.05). Similarly, the peak-to-peak duration (PTPd) of the evoked EMG increased faster at an earlier time to a higher asymptotical value in lengthened muscle (2.23 +/- 0.74 versus 1.77 +/- 0.54), compared to that of a shortened one (p < 0.05). These observations coincided with the higher rising rate and larger final value of the temporal coefficients, i.e., longer duration, in both type I and II MUs of lengthened muscles. From the observation of all parameters, the fatigue process in lengthened muscle proceeds faster than that in shortened muscle.
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Affiliation(s)
- Nan-Ying Yu
- Department of Physical Therapy, I-Shou University, Kaohsiung, Taiwan, Republic of China
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Weir JP, Beck TW, Cramer JT, Housh TJ. Is fatigue all in your head? A critical review of the central governor model. Br J Sports Med 2006; 40:573-86; discussion 586. [PMID: 16799110 PMCID: PMC2564297 DOI: 10.1136/bjsm.2005.023028] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2006] [Indexed: 11/04/2022]
Abstract
The central governor model has recently been proposed as a general model to explain the phenomenon of fatigue. It proposes that the subconscious brain regulates power output (pacing strategy) by modulating motor unit recruitment to preserve whole body homoeostasis and prevent catastrophic physiological failure such as rigor. In this model, the word fatigue is redefined from a term that describes an exercise decline in the ability to produce force and power to one of sensation or emotion. The underpinnings of the central governor model are the refutation of what is described variously as peripheral fatigue, limitations models, and the cardiovascular/anaerobic/catastrophe model. This argument centres on the inability of lactic acid models of fatigue to adequately explain fatigue. In this review, it is argued that a variety of peripheral factors other than lactic acid are known to compromise muscle force and power and that these effects may protect against "catastrophe". Further, it is shown that a variety of studies indicate that fatigue induced decreases in performance cannot be adequately explained by the central governor model. Instead, it is suggested that the concept of task dependency, in which the mechanisms of fatigue vary depending on the specific exercise stressor, is a more comprehensive and defensible model of fatigue. This model includes aspects of both central and peripheral contributions to fatigue, and the relative importance of each probably varies with the type of exercise.
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Affiliation(s)
- J P Weir
- Osteopathic Medical Center, Des Moines University, Des Moines, IA 50312, USA.
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Place N, Martin A, Ballay Y, Lepers R. Neuromuscular fatigue differs with biofeedback type when performing a submaximal contraction. J Electromyogr Kinesiol 2006; 17:253-63. [PMID: 16750638 DOI: 10.1016/j.jelekin.2006.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 03/23/2006] [Accepted: 04/03/2006] [Indexed: 11/25/2022] Open
Abstract
The aim of the study was to examine alterations in contractile and neural processes in response to an isometric fatiguing contraction performed with EMG feedback (constant-EMG task) when exerting 40% of maximal voluntary contraction (MVC) torque with the knee extensor muscles. A task with a torque feedback (constant-torque task) set at a similar intensity served as a reference task. Thirteen men (26+/-5 yr) attended two experimental sessions that were randomized across days. Endurance time was greater for the constant-EMG task compared with the constant-torque task (230+/-156 s vs. 101+/-32s, P<0.01). Average EMG activity for the knee extensor muscles increased from 33.5+/-4.5% to 54.7+/-21.7% MVC EMG during the constant-torque task (P<0.001), whereas the torque exerted during the constant-EMG task decreased from 42.8+/-3.0% to 17.9+/-5.6% MVC torque (P<0.001). Comparable reductions in knee extensors MVC (-15.7+/-8.7% for the constant-torque task vs. -17.5+/-9.8% for the constant-EMG task, P>0.05) and voluntary activation level were observed at exhaustion. In contrast, excitation-contraction coupling process, assessed with an electrically evoked twitch and doublet, was altered significantly more at the end of the constant-EMG task despite the absence of M-wave changes for both tasks. Present results suggest that prolonged contractions using EMG biofeedback should be used cautiously in rehabilitation programs.
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Affiliation(s)
- Nicolas Place
- INSERM ERM 207 Motricité-Plasticité Laboratory, Faculty of Sport Sciences, University of Burgundy, 21078 Dijon Cedex, France.
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Place N, Matkowski B, Martin A, Lepers R. Synergists activation pattern of the quadriceps muscle differs when performing sustained isometric contractions with different EMG biofeedback. Exp Brain Res 2006; 174:595-603. [PMID: 16708243 DOI: 10.1007/s00221-006-0504-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Accepted: 04/08/2006] [Indexed: 10/24/2022]
Abstract
The aims of the present study were to examine (1) endurance time and (2) activation pattern of vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles during fatiguing isometric knee extensions performed with different EMG biofeedbacks. Thirteen men (27 +/- 5 year) volunteered to participate in three experimental sessions. Each session involved a submaximal isometric contraction held until failure at an EMG level corresponding to 40% maximal voluntary contraction torque (MVC), with visual EMG biofeedback provided for either (1) RF muscle (RF task), (2) VL and VM muscles (Vasti task) or (3) the sum of the VL, VM and RF muscles (Quadriceps task). EMG activity of VL, VM and RF muscles was recorded during each of the three tasks and further analyzed. Time to task failures and MVC loss (P < 0.001) after exercises were similar (P > 0.05) between the three sessions (182 s and approximately 28%, respectively) (P > 0.05). Moreover, the magnitude of central and peripheral fatigue was not different at failure of the three tasks. Activation pattern was similar for knee extensors at the beginning of each task (P > 0.05). However, RF EMG activity decreased (P < 0.05) during the Vasti and the Quadriceps tasks (from approximately 33 to approximately 25% maximal EMG), whereas vasti EMG activity remained constant during the RF task ( approximately 41% maximal EMG). These findings suggest that (1) task failure occurs when sustaining a submaximal level of EMG activity for as long as possible and (2) CNS is not able to differentiate descending drive to the different heads of the quadriceps at the beginning of a sustained contraction, despite a different activation pattern for the bi-articular RF muscle compared to the mono-articular vasti muscles during fatigue.
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Affiliation(s)
- Nicolas Place
- INSERM ERM 207 Motricité Plasticité, Faculté des Sciences du Sport, Université de Bourgogne, Dijon Cedex, France.
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Desbrosses K, Babault N, Scaglioni G, Meyer JP, Pousson M. Neural Activation after Maximal Isometric Contractions at Different Muscle Lengths. Med Sci Sports Exerc 2006; 38:937-44. [PMID: 16672848 DOI: 10.1249/01.mss.0000218136.58899.46] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To investigate i) whether neural activation dependence on muscle length is preserved with neuromuscular fatigue and ii) whether fatigue induced by a maximal isometric exercise is muscle length dependent. METHODS Twelve male subjects performed two fatiguing quadriceps muscle exercises: FS is the fatigue carried out at short muscle length (S) (S = 40 degrees of knee flexion) and FL is the fatigue at long muscle length (L) (L = 100 degrees). Before and after each fatiguing exercise (i.e., three maximal isometric contractions maintained until 80, 60, and 40% of the initial maximal torque, respectively), activation level (AL, assessed by means of twitch interpolation technique), EMG activity (RMS), and peak doublet torque (Pd) were measured at the two lengths (S and L). RESULTS First, AL was greater (P < 0.05) at L compared with S before and after both exercises. Second, despite a similar decrease in maximal voluntary torque (approximately 21% of the initial value) after the two exercises, AL and RMS were significantly reduced after FS (P < 0.05) but remained unchanged after FL, whereas the Pd decrease was more pronounced after FL than FS (P < 0.05). Nevertheless, after a given fatiguing exercise (i.e., FS or FL), AL, RMS, and Pd changes were similar at both postexercise test lengths (S and L). CONCLUSION These results clearly demonstrate that i) the neural activation dependence on quadriceps muscle length is maintained with fatigue, and ii) neuromuscular fatigue after maximal isometric contractions is dependent on the muscle length at which the exercise is performed: short length preferentially induces neural activation impairment, whereas long length leads to higher contractile failure.
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Affiliation(s)
- Kévin Desbrosses
- INSERM/ERIT-M Motricity-Plasticity, Faculty of Sport Science, University of Burgundy, Dijon, France.
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Prasartwuth O, Allen TJ, Butler JE, Gandevia SC, Taylor JL. Length-dependent changes in voluntary activation, maximum voluntary torque and twitch responses after eccentric damage in humans. J Physiol 2006; 571:243-52. [PMID: 16357013 PMCID: PMC1805656 DOI: 10.1113/jphysiol.2005.101600] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Accepted: 12/12/2005] [Indexed: 12/26/2022] Open
Abstract
To assess the contribution of central and peripheral factors to changes in maximum voluntary force and its length dependence after eccentric muscle damage, voluntary and twitch torque were measured across a wide angular range, along with voluntary activation using twitch interpolation. Isometric torque from both maximum voluntary contractions (MVCs) and paired twitches to motor nerve stimulation were measured from 60 to 150 deg elbow flexion in 10 deg increments in eight subjects. Optimal angles were determined by curve fitting. Each subject then performed eccentric contractions until voluntary torque had decreased by approximately 40%. Measurements were repeated at 2 h, 1 day and 8 days post-exercise to follow acute and longer-term changes. Before exercise, the optimal angle was in the mid-range (93+/-10 deg; mean+/-s.d.) for MVCs, and at a more extended elbow angle for the twitch (106+/-6 deg, P < 0.05). Voluntary activation was generally high (> 94%) but depended on elbow angle, with activation being approximately 4% lower at the most flexed compared to the most extended angle. Two hours after exercise, MVCs decreased 40%, while twitch torque declined 70%. All subjects showed a shift in optimal angle to longer muscle lengths for MVCs (17+/-16 deg at 2 h, 14+/-7 deg at day 1, P < 0.05). This shift contributed minimally (approximately 3%) to the reduction in torque at 90 deg, as the torque-angle relation was relatively flat around the optimum. The twitch showed a smaller shift (approximately 4 deg) to longer lengths which was not statistically significant. Voluntary activation was significantly impaired in the early stages after exercise (2 h and day 1, P < 0.05), particularly at short muscle lengths. By 8 days after exercise, the optimal angle had returned to pre-exercise values, but MVC, twitch torque and voluntary activation had not fully recovered. Eccentric exercise causes a short-term shift in the optimal angle for MVCs and produces a length-dependent impairment in voluntary activation. Therefore, it appears that both central and peripheral factors limit muscle performance following eccentric damage, with limits to voluntary drive being especially important at short lengths.
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Affiliation(s)
- O Prasartwuth
- Prince of Wales Medical Research Institute, University of New South Wales, Barker Street, Randwick, Sydney, NSW 2031, Australia
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de Ruiter CJ, de Boer MD, Spanjaard M, de Haan A. Knee angle-dependent oxygen consumption during isometric contractions of the knee extensors determined with near-infrared spectroscopy. J Appl Physiol (1985) 2005; 99:579-86. [PMID: 15774700 DOI: 10.1152/japplphysiol.01420.2004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fatigue resistance of knee extensor muscles is higher during voluntary isometric contractions at short compared with longer muscle lengths. In the present study we hypothesized that this would be due to lower energy consumption at short muscle lengths. Ten healthy male subjects performed isometric contractions with the knee extensor muscles at a 30, 60, and 90 degrees knee angle (full extension = 0 degrees ). At each angle, muscle oxygen consumption (m.VO2) of the rectus femoris, vastus lateralis, and vastus medialis muscle was obtained with near-infrared spectroscopy. m.VO2 was measured during maximal isometric contractions and during contractions at 10, 30, and 50% of maximal torque capacity. During all contractions, blood flow to the muscle was occluded with a pressure cuff (450 mmHg). m.VO2 significantly (P < 0.05) increased with torque and at all torque levels, and for each of the three muscles. m.VO2 was significantly lower at 30 degrees compared with 60 degrees and 90 degrees and m.VO2 was similar (P > 0.05) at 60 degrees and 90 degrees . Across all torque levels, average (+/- SD) m.VO2 at the 30 degrees angle for vastus medialis, rectus femoris, and vastus lateralis, respectively, was 70.0 +/- 10.4, 72.2 +/- 12.7, and 75.9 +/- 8.0% of the average m.VO2 obtained for each torque at 60 and 90 degrees . In conclusion, oxygen consumption of the knee extensors was significantly lower during isometric contractions at the 30 degrees than at the 60 degrees and 90 degrees knee angle, which probably contributes to the previously reported longer duration of sustained isometric contractions at relatively short muscle lengths.
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Affiliation(s)
- C J de Ruiter
- Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands.
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