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Li J, Soh KG, Loh SP. The impact of post-activation potentiation on explosive vertical jump after intermittent time: a meta-analysis and systematic review. Sci Rep 2024; 14:17213. [PMID: 39060296 PMCID: PMC11282079 DOI: 10.1038/s41598-024-67995-7] [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: 02/01/2024] [Accepted: 07/18/2024] [Indexed: 07/28/2024] Open
Abstract
The optimal intermittent time for post-activation potentiation (PAP) training remains uncertain and contentious. This study employed a meta-analysis to systematically evaluate the effect of different intermittent times on PAP in relation to explosive vertical jump height. Relevant literature was sourced from CNKI, Wanfang, VIP, CBM, PubMed, Web of Science, and Google Scholar databases using keywords such as "postactivation potentiation," "activation enhancement effect," "PAP," "explosive vertical jump," "explosive vertical high jump," and "intermittent time." The search covered publications from the inception of each database until June 2024. Studies involving athletes (regardless of sport type) undergoing PAP training were included, with no restrictions on the methods used to induce PAP. Comparative analysis focused on the heights of countermovement jumps (CMJ) and peak ground reaction force (GRF) before and after interventions. The quality of the included studies was assessed using the Cochrane Risk of Bias Tool, and data were analyzed using RevMan5.3. The study included a total of 21 papers with 327 subjects, primarily using the squat as the method of PAP induction. The meta-analysis revealed that intermittent times of 4 min [MD = - 0.03, 95% CI: - 0.04 ~ - 0.01; Z = 2.71, P = 0.007] and 5-8 min [MD = - 0.03, 95% CI: - 0.04 ~ - 0.01; Z = 3.07, P = 0.002] significantly increased the height of explosive vertical CMJs. However, intermittent times of 1-3 min [MD = -0.00, 95% CI: - 0.01 ~ 0.01; Z = 0.38, P = 0.70] and 10-24 min [MD = - 0.01, 95% CI: - 0.02 ~ 0.00; Z = 1.43, P = 0.15] did not show significant effects on CMJ height. These findings indicate that 4-min and 5-8 min intervals significantly enhance CMJ height, while intervals shorter than 4 min or longer than 8 min do not have a significant impact.
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Affiliation(s)
- Jiazhe Li
- Department of Sports Studies, Faculty of Educational Studies, Universiti Putra Malaysia, Serdang, Malaysia.
| | - Kim Geok Soh
- Department of Sports Studies, Faculty of Educational Studies, Universiti Putra Malaysia, Serdang, Malaysia
| | - Su Peng Loh
- Department of Nutrition, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
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2
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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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Hinks A, Dalton BE, Mashouri P, Flewwelling LD, Pyle WG, Cheng AJ, Power GA. Time course changes in in vivo muscle mechanical function and Ca 2+ regulation of force following experimentally induced gradual ovarian failure in mice. Exp Physiol 2024; 109:711-728. [PMID: 38500268 PMCID: PMC11061627 DOI: 10.1113/ep091735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 02/05/2024] [Indexed: 03/20/2024]
Abstract
The abrupt cessation of ovarian hormone release is associated with declines in muscle contractile function, yet the impact of gradual ovarian failure on muscle contractility across peri-, early- and late-stage menopause remains unclear. In this study, a 4-vinylcyclohexene diepoxide (VCD)-induced ovarian failure mouse model was used to examine time course changes in muscle mechanical function. Plantar flexors of female mice (VCD: n = 10; CON: n = 8) were assessed at 40 (early perimenopause), 80 (late perimenopause), 120 (menopause onset) and 176 (late menopause) days post-initial VCD injection. A torque-frequency relationship was established across a range of frequencies (10-200 Hz). Isotonic dynamic contractions were elicited against relative loads (10-80% maximal isometric torque) to determine the torque-velocity-power relationship. Mice then performed a fatigue task using intermittent 100 Hz isometric contractions until torque dropped by 60%. Recovery of twitch, 10 Hz and 100 Hz torque were tracked for 10 min post-task failure. Additionally, intact muscle fibres from the flexor digitorum brevis underwent a fatigue task (50 repetitions at 70 Hz), and 10 and 100 Hz tetanic [Ca2+] were monitored for 10 min afterward. VCD mice exhibited 16% lower twitch torque than controls across all time points. Apart from twitch torque, 10 Hz torque and 10 Hz tetanic [Ca2+], where VCD showed greater values relative to pre-fatigue during recovery, no significant differences were observed between control and VCD mice during recovery. These results indicate that gradual ovarian failure has minimal detriments to in vivo muscle mechanical function, with minor alterations observed primarily for low-frequency stimulation during recovery from fatigue.
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Affiliation(s)
- Avery Hinks
- Department of Human Health and Nutritional Sciences, College of Biological SciencesUniversity of GuelphGuelphOntarioCanada
| | - Benjamin E. Dalton
- Department of Human Health and Nutritional Sciences, College of Biological SciencesUniversity of GuelphGuelphOntarioCanada
| | - Parastoo Mashouri
- Department of Human Health and Nutritional Sciences, College of Biological SciencesUniversity of GuelphGuelphOntarioCanada
| | - Luke D. Flewwelling
- Muscle Health Research Centre, School of Kinesiology and Health Sciences, Faculty of HealthYork UniversityTorontoCanada
| | - William Glen Pyle
- IMPART Team Canada, Dalhousie MedicineDalhousie UniversitySaint JohnNew BrunswickCanada
| | - Arthur J. Cheng
- Muscle Health Research Centre, School of Kinesiology and Health Sciences, Faculty of HealthYork UniversityTorontoCanada
| | - Geoffrey A. Power
- Department of Human Health and Nutritional Sciences, College of Biological SciencesUniversity of GuelphGuelphOntarioCanada
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Coratella G. Appropriate Reporting of Exercise Variables in Resistance Training Protocols: Much more than Load and Number of Repetitions. SPORTS MEDICINE - OPEN 2022; 8:99. [PMID: 35907047 PMCID: PMC9339067 DOI: 10.1186/s40798-022-00492-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 07/21/2022] [Indexed: 12/03/2022]
Abstract
Manipulating resistance training variables is crucial to plan the induced stimuli correctly. When reporting the exercise variables in resistance training protocols, sports scientists and practitioners often refer to the load lifted and the total number of repetitions. The present conceptual review explores all within-exercise variables that may influence the strength and hypertrophic gains, and the changes in muscle architecture. Together with the (1) load and (2) the number of repetitions, (3) performing repetitions to failure or not to failure, (4) the displacement of the load or the range of movement (full or partial), (5) the portion of the partial movement to identify the muscle length at which the exercise is performed, (6) the total time under tension, the duration of each phase and the position of the two isometric phases, (7) whether the concentric, eccentric or concentric-eccentric phase is performed, (8) the use of internal or external focus and (9) the inter-set rest may all have repercussions on the adaptations induced by each resistance exercise. Manipulating one or more variable allows to increase, equalize or decrease the stimuli related to each exercise. Sports scientists and practitioners are invited to list all aforementioned variables for each exercise when reporting resistance training protocols.
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Affiliation(s)
- Giuseppe Coratella
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Via Giuseppe Colombo 71, 20133, Milan, Italy.
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Zero AM, Paris MT, Rice CL. Frequency dependent coexistence of muscle fatigue and potentiation assessed by concentric isotonic contractions in human plantar flexors. J Appl Physiol (1985) 2022; 133:490-505. [PMID: 35796610 DOI: 10.1152/japplphysiol.00214.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose was to investigate whether post-activation potentiation (PAP) mitigates power (i.e., torque x angular velocity) loss during dynamic fatiguing contractions and subsequent recovery by enhancing either muscle torque or angular velocity in human plantar flexors. In 12 participants, electrically stimulated (1, 10 and 50 Hz) dynamic contractions were done during a voluntary isotonic fatiguing protocol (20 and 50% voluntary decreases) until a 75% loss in voluntary peak power, and throughout 30 minutes of recovery. At the initial portion of fatigue (20% decrease), power responses of evoked low frequencies (1 and 10 Hz) were enhanced due to PAP (156 and 137%, respectively, P<0.001), while voluntary maximal efforts were depressed due to fatiguing mechanisms. Following the fatiguing task, prolonged low-frequency force depression (PLFFD) was evident by reduced 10:50 Hz peak power ratios (21 - 24%) from 3-min onwards during the 30-min recovery (P<0.005). Inducing PAP with maximal voluntary contractions during PLFFD enhanced the peak power responses of low frequencies (1 and 10 Hz) by 128 - 160 %, P<0.01. This PAP response mitigated the effects of PLFFD as the 1:50 (P<0.05) and 10:50 (P>0.4) Hz peak power ratios were greater or not different from the pre-fatigue values. Additionally, PAP enhanced peak torque more than peak angular velocity during both baseline and fatigue measurements (P<0.03). These results indicate that PAP can ameliorate PLFFD acutely when evaluated during concentric isotonic contractions and that peak torque is enhanced to a greater degree compared to peak angular velocity at baseline and in a fatigued state.
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Affiliation(s)
- Alexander M Zero
- School of Kinesiology, Faculty of Health Sciences, grid.39381.30Western University, London, ON, Canada
| | - Michael T Paris
- School of Kinesiology, Faculty of Health Sciences, grid.39381.30Western University, London, ON, Canada
| | - Charles L Rice
- Department of Anatomy and Cell Biology, grid.443228.bWestern University, London, Ontario, Canada
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Rakshit R, Xiang Y, Yang J. Functional muscle group- and sex-specific parameters for a three-compartment controller muscle fatigue model applied to isometric contractions. J Biomech 2021; 127:110695. [PMID: 34454329 DOI: 10.1016/j.jbiomech.2021.110695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/10/2021] [Accepted: 08/12/2021] [Indexed: 02/06/2023]
Abstract
The three-compartment controller with enhanced recovery (3CC-r) model of muscle fatigue has previously been validated separately for both sustained (SIC) and intermittent isometric contractions (IIC) using different objective functions, but its performance has not yet been tested against both contraction types simultaneously using a common objective function. Additionally, prior validation has been performed using common parameters at the joint level, whereas applications to many real-world tasks will require the model to be applied to agonistic and synergistic muscle groups. Lastly, parameters for the model have previously been derived for a mixed-sex cohort not considering the differece in fatigabilities between the sexes. In this work we validate the 3CC-r model using a comprehensive isometric contraction database drawn from 172 publications segregated by functional muscle group (FMG) and sex. We find that prediction errors are reduced by 19% on average when segregating the dataset by FMG alone, and by 34% when segregating by both sex and FMG. However, minimum prediction errors are found to be higher when validated against both SIC and IIC data together using torque decline as the outcome variable than when validated sequentially against hypothesized SIC intensity-endurance time curves with endurance time as the outcome variable and against raw IIC data with torque decline as the outcome variable.
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Affiliation(s)
- Ritwik Rakshit
- Human-Centric Design Research Lab, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409, USA
| | - Yujiang Xiang
- School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK 74078, USA
| | - James Yang
- Human-Centric Design Research Lab, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
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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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Dotan R, Woods S, Contessa P. On the reliability and validity of central fatigue determination. Eur J Appl Physiol 2021; 121:2393-2411. [PMID: 33966110 DOI: 10.1007/s00421-021-04700-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 04/24/2021] [Indexed: 11/30/2022]
Abstract
Physical performance fatigue can be ascribed to both peripheral and central components. Central fatigue, however, is an elusive entity, consisting of cognitive/sensory component and presumably also a neuro-physiological component that are difficult to tease apart and assess independently of each other. The most widely accepted method for the assessment of central fatigue is based on the premise that decreasing volitional muscle activation (VA), as determined by the interpolated twitch technique (ITT) in fatiguing muscles, reflects increasing central fatigue. Suffering its own shortcomings, the validity of VA determination under fatigued conditions has never been proven and is only assumed. This review presents evidence that questions ITT's reliability and validity in reflecting VA in the fatiguing muscle and, consequently, VA's validity for central fatigue assessment. Specifically highlighted is the paradox of children and endurance athletes, who share striking endurance characteristics, being claimed as more centrally fatigable than untrained adults. Further research and new directions are needed for confirming and quantifying central fatigue and teasing apart its psychologic and neuromotor components.
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Affiliation(s)
- Raffy Dotan
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St Catharines, ON, Canada.
| | - Stacey Woods
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St Catharines, ON, Canada
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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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Forman DA, Forman GN, Mugnosso M, Zenzeri J, Murphy B, Holmes MWR. Sustained Isometric Wrist Flexion and Extension Maximal Voluntary Contractions Similarly Impair Hand-Tracking Accuracy in Young Adults Using a Wrist Robot. Front Sports Act Living 2020; 2:53. [PMID: 33345044 PMCID: PMC7739644 DOI: 10.3389/fspor.2020.00053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 04/16/2020] [Indexed: 11/13/2022] Open
Abstract
Due to their stabilizing role, the wrist extensor muscles demonstrate an earlier onset of performance fatigability and may impair movement accuracy more than the wrist flexors. However, minimal fatigue research has been conducted at the wrist. Thus, the purpose of this study was to examine how sustained isometric contractions of the wrist extensors/flexors influence hand-tracking accuracy. While gripping the handle of a three-degrees-of-freedom wrist manipulandum, 12 male participants tracked a 2:3 Lissajous curve (±32° wrist flexion/extension; ±18° radial/ulnar deviation). A blue, circular target moved about the trajectory and participants tracked the target with a yellow circle (corresponding to the handle's position). Five baseline tracking trials were performed prior to the fatiguing task. Participants then exerted either maximal wrist extension or flexion force (performed on separate days) against a force transducer until they were unable to maintain 25% of their pre-fatigue maximal voluntary contraction (MVC). Participants then performed 7 tracking trials from immediately post-fatigue to 10 min after. Performance fatigability was assessed using various metrics to account for errors in position-tracking, error tendencies, and movement smoothness. While there were no differences in tracking error between flexion/extension sessions, tracking error significantly increased immediately post-fatigue (Baseline: 1.40 ± 0.54°, Post-fatigue: 2.02 ± 0.51°, P < 0.05). However, error rapidly recovered, with no differences in error from baseline after 1-min post-fatigue. These findings demonstrate that sustained isometric extension/flexion contractions similarly impair tracking accuracy of the hand. This work serves as an important step to future research into workplace health and preventing injuries of the distal upper-limb.
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Affiliation(s)
- Davis A Forman
- Faculty of Science, Ontario Tech University, Oshawa, ON, Canada
| | - Garrick N Forman
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
| | - Maddalena Mugnosso
- Robotics, Brain and Cognitive Sciences, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Jacopo Zenzeri
- Robotics, Brain and Cognitive Sciences, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Bernadette Murphy
- Faculty of Health Sciences, Ontario Tech University, Oshawa, ON, Canada
| | - Michael W R Holmes
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
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Piponnier E, Martin V, Chalchat E, Bontemps B, Julian V, Bocock O, Duclos M, Ratel S. Effect of Muscle-Tendon Unit Length on Child-Adult Difference in Neuromuscular Fatigue. Med Sci Sports Exerc 2020; 51:1961-1970. [PMID: 31415444 DOI: 10.1249/mss.0000000000001981] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The purpose of this study was to compare the development and etiology of neuromuscular fatigue of the knee extensor muscles at different muscle-tendon unit (MTU) lengths during repeated maximal voluntary isometric contractions (MVIC) between boys and men. METHODS Twenty-two prepubertal boys (9-11 yr) and 22 men (18-30 yr) performed three knee extensor fatigue protocols at short (SHORT), optimal (OPT), and long (LONG) MTU lengths, consisting of repeating 5-s MVIC interspersed with 5-s passive recovery periods until torque reached 60% of the initial MVIC torque. The etiology of neuromuscular fatigue was identified using noninvasive methods such as surface electromyography, near-infrared spectroscopy, magnetic nerve stimulation and twitch interpolation technique. RESULTS The number of repetitions was significantly lower in men at OPT (14.8 ± 3.2) and LONG (15.8 ± 5.8) than boys (39.7 ± 18.4 and 29.5 ± 10.2, respectively; P < 0.001), whereas no difference was found at SHORT between both age groups (boys, 33.7 ± 15.4; men, 40.9 ± 14.2). At OPT and LONG boys showed a lower reduction in the single potentiated twitch (Qtwpot) and a greater decrease in the voluntary activation level than men. At SHORT, both populations displayed a moderate Qtwpot decrement and a significant voluntary activation reduction (P < 0.001). The differences in maximal torque between boys and men were almost twice greater at OPT (223.9 N·m) than at SHORT (123.3 N·m) and LONG (136.5 N·m). CONCLUSIONS The differences in neuromuscular fatigue between children and adults are dependent on MTU length. Differences in maximal torque could underpin differences in neuromuscular fatigue between children and adults at OPT and SHORT. However, at LONG these differences do not seem to be explained by differences in maximal torque. The origins of this specific effect of MTU length remain to be determined.
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Affiliation(s)
- Enzo Piponnier
- Clermont-Auvergne University, AME2P, Clermont-Ferrand, FRANCE
| | - Vincent Martin
- Clermont-Auvergne University, AME2P, Clermont-Ferrand, FRANCE
| | - Emeric Chalchat
- Clermont-Auvergne University, AME2P, Clermont-Ferrand, FRANCE
| | | | | | - Olivia Bocock
- Clermont University Hospital, Clermont-Ferrand, FRANCE
| | | | - Sébastien Ratel
- Clermont-Auvergne University, AME2P, Clermont-Ferrand, FRANCE
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Akagi R, Sato S, Yoshihara K, Ishimatsu H, Ema R. Sex difference in fatigability of knee extensor muscles during sustained low-level contractions. Sci Rep 2019; 9:16718. [PMID: 31723215 PMCID: PMC6853909 DOI: 10.1038/s41598-019-53375-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 10/31/2019] [Indexed: 11/29/2022] Open
Abstract
This study investigated whether the sex difference in fatigability of the knee extensors (KE) is explained by the sex difference in fatigue-induced changes in the shear modulus of one or more muscles of KE in 18 young men and 23 young women. The shear moduli of the resting rectus femoris and medial and lateral vastus muscles (VL) were measured before and after a sustained contraction at 20% peak torque during a maximal voluntary isometric contraction of KE until the endurance limit, in addition to evoked torque and voluntary activation (VA%). The fatigue-induced decrease in maximal muscle strength was more prominent in men than in women. Only the VL shear modulus for men increased after the fatiguing task, and a sex difference was observed in the percentage change in the VL shear modulus before and after the fatiguing task. The fatigue-induced decreased ratio was greater for men than for women in evoked torque, but not in VA%. These results suggest that although peripheral and central fatigue both influenced the fatigue-induced decrease in maximal muscle strength regardless of sex, the sex difference in KE fatigability is explained by that in peripheral fatigue, particularly the degree of peripheral VL fatigue.
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Affiliation(s)
- Ryota Akagi
- College of Systems Engineering and Science, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama, 337-8570, Japan. .,Graduate School of Engineering and Science, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama, 337-8570, Japan. .,QOL Improvement and Life Science Consortium, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama, 337-8570, Japan.
| | - Shinya Sato
- Graduate School of Engineering and Science, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama, 337-8570, Japan
| | - Kana Yoshihara
- College of Systems Engineering and Science, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama, 337-8570, Japan
| | - Hideki Ishimatsu
- College of Systems Engineering and Science, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama, 337-8570, Japan
| | - Ryoichi Ema
- School of Management, Shizuoka Sangyo University, 1572-1 Owara, Iwata-shi, Shizuoka, 438-0043, Japan
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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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Zimmermann HB, MacIntosh BR, Dal Pupo J. Does postactivation potentiation (PAP) increase voluntary performance? Appl Physiol Nutr Metab 2019; 45:349-356. [PMID: 31557447 DOI: 10.1139/apnm-2019-0406] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The transient increase in torque of an electrically evoked twitch following a voluntary contraction is called postactivation potentiation (PAP). Phosphorylation of myosin regulatory light chains is the most accepted mechanism explaining the enhanced electrically evoked twitch torque. While many authors attribute voluntary postactivation performance enhancement (PAPE) to the positive effects of PAP, few actually confirmed that contraction was indeed potentiated using electrical stimulation (twitch response) at the time that PAPE was measured. Thus, this review aims to investigate if increases in voluntary performance after a conditioning contraction (CC) are related to the PAP phenomenon. For this, studies that confirmed the presence of PAP through an evoked response after a voluntary CC and concurrently evaluated PAPE were reviewed. Some studies reported increases in PAPE when PAP reaches extremely high values. However, PAPE has also been reported when PAP was not present, and unchanged/diminished performance has been identified when PAP was present. This range of observations demonstrates that mechanisms of PAPE are different from mechanisms of PAP. These mechanisms of PAPE still need to be understood and those studying PAPE should not assume that regulatory light chain phosphorylation is the mechanism for such enhanced voluntary performance. Novelty The occurrence of PAP does not necessarily mean that the voluntary performance will be improved. Improvement in voluntary performance is sometimes observed when the PAP level reaches extremely high values. Other mechanisms may be more relevant than that for PAP in the manifestation of acute increases in performance following a conditioning contraction.
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Affiliation(s)
- Haiko Bruno Zimmermann
- Biomechanics Laboratory, Sports Center, Federal University of Santa Catarina, Florianopolis, SC 88040900, Brazil
| | - Brian R MacIntosh
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Juliano Dal Pupo
- Biomechanics Laboratory, Sports Center, Federal University of Santa Catarina, Florianopolis, SC 88040900, Brazil
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Wu R, Delahunt E, Ditroilo M, Lowery MM, Segurado R, De Vito G. Changes in knee joint angle affect torque steadiness differently in young and older individuals. J Electromyogr Kinesiol 2019; 47:49-56. [DOI: 10.1016/j.jelekin.2019.05.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 05/13/2019] [Accepted: 05/13/2019] [Indexed: 12/01/2022] Open
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A phenomenological model of the time course of maximal voluntary isometric contraction force for optimization of complex loading schemes. Eur J Appl Physiol 2018; 118:2587-2605. [DOI: 10.1007/s00421-018-3983-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 08/29/2018] [Indexed: 10/28/2022]
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17
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Garnier YM, Paizis C, Lepers R. Corticospinal changes induced by fatiguing eccentric versus concentric exercise. Eur J Sport Sci 2018; 19:166-176. [PMID: 30016203 DOI: 10.1080/17461391.2018.1497090] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The present study assessed neuromuscular and corticospinal changes during and after a fatiguing submaximal exercise of the knee extensors in different modes of muscle contraction. Twelve subjects performed two knee extensors exercises in a concentric or eccentric mode, at the same torque and with a similar total impulse. Exercises consisted of 10 sets of 10 repetitions at an intensity of 80% of the maximal voluntary isometric contraction torque (MVIC). MVIC, maximal voluntary activation level (VAL) and responses of electrically evoked contractions of the knee extensors were assessed before and after exercise. Motor evoked potential amplitude (MEP) and cortical silent period (CSP) of the vastus medialis (VM) and rectus femoris (RF) muscles were assessed before, during and after exercise. Similar reductions of the MVIC (-13%), VAL (-12%) and a decrease in the peak twitch (-12%) were observed after both exercises. For both VM and RF muscles, MEP amplitude remained unchanged during either concentric or eccentric exercises. No change of the MEP amplitude input-output curves was observed post-exercise. For the RF muscle, CSP increased during the concentric exercise and remained lengthened after this exercise. For the VM muscle, CSP was reduced after the eccentric exercise only. For a similar amount of total impulse, concentric and eccentric knee extensor contractions led to similar exercise-induced neuromuscular response changes. For the two muscles investigated, no modulation of corticospinal excitability was observed during or after either concentric or eccentric exercises. However, intracortical inhibition showed significant modulations during and after exercise.
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Affiliation(s)
- Yoann M Garnier
- a INSERM UMR1093-CAPS , Université Bourgogne Franche-Comté, UFR des Sciences du Sport , Dijon , France
| | - Christos Paizis
- a INSERM UMR1093-CAPS , Université Bourgogne Franche-Comté, UFR des Sciences du Sport , Dijon , France.,b Centre d'Expertise de la Performance , Université Bourgogne Franche-Comté, UFR des Sciences du Sport , Dijon , France
| | - Romuald Lepers
- a INSERM UMR1093-CAPS , Université Bourgogne Franche-Comté, UFR des Sciences du Sport , Dijon , France
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18
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Garnier YM, Lepers R, Dubau Q, Pageaux B, Paizis C. Neuromuscular and perceptual responses to moderate-intensity incline, level and decline treadmill exercise. Eur J Appl Physiol 2018; 118:2039-2053. [DOI: 10.1007/s00421-018-3934-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 07/05/2018] [Indexed: 11/28/2022]
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Coratella G, Grosprêtre S, Gimenez P, Mourot L. Greater fatigability in knee-flexors vs. knee-extensors after a standardized fatiguing protocol. Eur J Sport Sci 2018; 18:1110-1118. [PMID: 29738677 DOI: 10.1080/17461391.2018.1469674] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The present study aimed to investigate the effects of a standardized fatiguing protocol on central and peripheral fatigue in knee-flexors and knee-extensors. Thirteen healthy men (age: 23 ± 3 years; height: 1.78 ± 0.09 m; body-mass: 73.6 ± 9.2 kg) volunteered for the present study. Maximal voluntary contraction (MVC), Electromyography (EMG) activity, voluntary activation level (VAL) as an index of central fatigue and twitch potentiation as an index of peripheral fatigue were measured before and after the fatiguing protocol. The fatiguing protocol consisted of a 0.6 duty-cycle to exhaustion (6 s isometric contraction, 4 s recovery) at 70% MVC. After the fatiguing protocol, MVC decreased in both (Effect-size (ES) = 1.14) and knee-extensors (ES = 1.14), and EMG activity increased in both knee-flexors (ES = 2.33) and knee-extensors (ES = 1.54). Decreases in VAL occurred in knee-flexors (ES = 0.92) but not in knee-extensors (ES = 0.04). Decreases in potentiation occurred in both knee-flexors (ES = 0.84) and knee-extensors (ES = 0.58). The greater central occurrence of fatigue in knee-flexors than in knee-extensors may depend on the different muscle morphology and coupled with a greater tolerance to fatigue in knee-extensors. The present data add further insight to the complicated knee-flexors-to-knee-extensors strength relationship and the mechanisms behind the different occurrence of fatigue.
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Affiliation(s)
- Giuseppe Coratella
- a EA4660-C3S Laboratory - Culture, Sports, Health and Society and Exercise Performance, Health, Innovation Platform , Univ. Bourgogne Franche-Comté , Besançon , France.,b Department of Biomedical Sciences for Health , University of Milan , Milan , Italy
| | - Sidney Grosprêtre
- a EA4660-C3S Laboratory - Culture, Sports, Health and Society and Exercise Performance, Health, Innovation Platform , Univ. Bourgogne Franche-Comté , Besançon , France
| | - Philippe Gimenez
- a EA4660-C3S Laboratory - Culture, Sports, Health and Society and Exercise Performance, Health, Innovation Platform , Univ. Bourgogne Franche-Comté , Besançon , France
| | - Laurent Mourot
- c EA3920-Prognostic Markers and Regulatory Factors of Heart and Vascular Diseases and Exercise Performance, Health, Innovation Platform , Univ. Bourgogne Franche-Comté , Besançon , France.,d Department of Physical Training , Tomsk Polytechnic University , Tomsk , Russia
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20
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Kuzyk SL, Smart RR, Simpson CL, Fedorov A, Jakobi JM. Influence of fascicle length on twitch potentiation of the medial gastrocnemius across three ankle angles. Eur J Appl Physiol 2018; 118:1199-1207. [PMID: 29600331 DOI: 10.1007/s00421-018-3849-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Accepted: 03/14/2018] [Indexed: 10/17/2022]
Abstract
PURPOSE Length dependence of post-activation potentiation (PAP) is a well-established phenomenon in animal models but less certain in intact whole human muscles. Recent advances in B-mode ultrasonography provide real-time imaging and evaluation of human muscle fascicles in vivo, thus removing the assumption that joint positioning alters fascicle length and influences the extent of PAP. The purpose of this study was to determine whether a conditioning maximal voluntary contraction (MVC) would influence the return of medial gastrocnemius (MG) fascicles to baseline length and alter the extent of twitch potentiation between three ankle positions. METHODS Ultrasonography was used to measure MG fascicle length for baseline and potentiated twitches at angles of 10° dorsiflexion (DF), 0° neutral (NEU-tibia perpendicular to the sole of the foot), and 20° plantar flexion (PF). A MVC was used as a conditioning contraction and PAP determined for each ankle angle. RESULTS PAP of the plantar flexors was greater in PF (28.8 ± 2.6%) compared to NEU (19.8 ± 1.8%; p < 0.05) and DF (9.3 ± 2.8%; p < 0.0001). In PF, fascicle lengths (4.64 ± 0.17 cm) were shorter than both NEU (5.78 ± 0.15 cm; p < 0.0001) and DF (6.09 ± 0.15 cm; p < 0.0001). Fascicle lengths for the baseline twitches were longer (5.92 ± 0.11 cm) than the potentiated twitches (5.83 ± 0.10 cm; p < 0.01) at all joint angles. CONCLUSION Although PAP is greatest in PF compared to NEU and DF, the higher PAP in the PF joint angle cannot be attributed to fascicles remaining shortened following the MVC because across all joint positions, fascicles are similarly shortened following the MVC.
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Affiliation(s)
- Samantha L Kuzyk
- Healthy Exercise and Aging Lab Group, School of Health and Exercise Sciences, University of British Columbia Okanagan, 133-1147 Research Road (Arts Building), Kelowna, BC, V1V 1V7, Canada
| | - Rowan R Smart
- Healthy Exercise and Aging Lab Group, School of Health and Exercise Sciences, University of British Columbia Okanagan, 133-1147 Research Road (Arts Building), Kelowna, BC, V1V 1V7, Canada
| | - Carey L Simpson
- Healthy Exercise and Aging Lab Group, School of Health and Exercise Sciences, University of British Columbia Okanagan, 133-1147 Research Road (Arts Building), Kelowna, BC, V1V 1V7, Canada
| | - Andrey Fedorov
- Healthy Exercise and Aging Lab Group, School of Health and Exercise Sciences, University of British Columbia Okanagan, 133-1147 Research Road (Arts Building), Kelowna, BC, V1V 1V7, Canada
| | - Jennifer M Jakobi
- Healthy Exercise and Aging Lab Group, School of Health and Exercise Sciences, University of British Columbia Okanagan, 133-1147 Research Road (Arts Building), Kelowna, BC, V1V 1V7, Canada.
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Cattagni T, Lepers R, Maffiuletti NA. Effects of neuromuscular electrical stimulation on contralateral quadriceps function. J Electromyogr Kinesiol 2018; 38:111-118. [PMID: 29202270 DOI: 10.1016/j.jelekin.2017.11.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 10/31/2017] [Accepted: 11/28/2017] [Indexed: 10/18/2022] Open
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Rodriguez-Falces J, Place N. Determinants, analysis and interpretation of the muscle compound action potential (M wave) in humans: implications for the study of muscle fatigue. Eur J Appl Physiol 2017; 118:501-521. [DOI: 10.1007/s00421-017-3788-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 12/06/2017] [Indexed: 10/18/2022]
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23
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Collins BW, Gale LH, Buckle NCM, Button DC. Corticospinal excitability to the biceps brachii and its relationship to postactivation potentiation of the elbow flexors. Physiol Rep 2017; 5:5/8/e13265. [PMID: 28455452 PMCID: PMC5408290 DOI: 10.14814/phy2.13265] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 03/30/2017] [Accepted: 04/05/2017] [Indexed: 11/24/2022] Open
Abstract
We examined the effects of a submaximal voluntary elbow flexor contraction protocol on measures of corticospinal excitability and postactivation potentiation of evoked muscle forces and if these measures were state‐dependent (rest vs. voluntary muscle contraction). Participants completed four experimental sessions where they rested or performed a 5% maximum voluntary contraction (MVC) of the elbow flexors prior to, immediately, and 5 min following a submaximal contraction protocol. During rest or 5% MVC, transcranial magnetic stimulation, transmastoid electrical stimulation, electrical stimulation of biceps brachii motor point and Erb's point were elicited to induce motor‐evoked potentials (MEPs), cervicomedullary MEPs (CMEPs), potentiated twitch (PT) force, and maximal muscle compound action potential (Mmax), respectively prior to, immediately, and 5 min postcontraction protocol. MEP amplitudes increased (215 and 165%Mmax, P ≤ 0.03) only at 1 and 6s postcontraction protocol, respectively during rest but not 5% MVC. CMEP amplitudes decreased during rest and 5% MVC (range:21–58%Mmax, P ≤ 0.04) for up to 81 sec postcontraction protocol. Peak twitch force increased immediately postcontraction protocol and remained elevated for 90 sec (range:122–147% increase, P < 0.05). There was a significant positive correlation between MEP and PT force during rest (r = 0.88, P = 0.01) and a negative correlation between CMEP and PT force during rest (r = −0.85, P < 0.02 and 5% MVC (r = −0.96, P < 0.01) immediately postcontraction protocol. In conclusion, the change in corticospinal and spinal excitability was state‐ and time‐dependent whereas spinal excitability and postactivation potentiation were time‐dependent following the contraction protocol. Changes in corticospinal excitability and postactivation potentiation correlated and were also state‐dependent.
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Affiliation(s)
- Brandon W Collins
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada
| | - Laura H Gale
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada
| | - Natasha C M Buckle
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada
| | - Duane C Button
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada .,BioMedical Sciences, Faculty of Medicine Memorial University St. John's, Newfoundland and Labrador, Canada
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Tsoukos A, Bogdanis GC, Terzis G, Veligekas P. Acute Improvement of Vertical Jump Performance After Isometric Squats Depends on Knee Angle and Vertical Jumping Ability. J Strength Cond Res 2016; 30:2250-7. [PMID: 26808841 DOI: 10.1519/jsc.0000000000001328] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Tsoukos, A, Bogdanis, GC, Terzis, G, and Veligekas, P. Acute improvement of vertical jump performance after isometric squats depends on knee angle and vertical jumping ability. J Strength Cond Res 30(8): 2250-2257, 2016-This study examined the acute effects of maximum isometric squats at 2 different knee angles (90 or 140°) on countermovement jump (CMJ) performance in power athletes. Fourteen national-level male track and field power athletes completed 3 main trials (2 experimental and 1 control) in a randomized and counterbalanced order 1 week apart. Countermovement jump performance was evaluated using a force-plate before and 15 seconds, 3, 6, 9, and 12 minutes after 3 sets of 3 seconds maximum isometric contractions with 1-minute rest in between, from a squat position with knee angle set at 90 or 140°. Countermovement jump performance was improved compared with baseline only in the 140° condition by 3.8 ± 1.2% on the 12th minute of recovery (p = 0.027), whereas there was no change in CMJ height in the 90° condition. In the control condition, there was a decrease in CMJ performance over time, reaching -3.6 ± 1.2% (p = 0.049) after 12 minutes of recovery. To determine the possible effects of baseline jump performance on subsequent CMJ performance, subjects were divided into 2 groups ("high jumpers" and "low jumpers"). The baseline CMJ values of "high jumpers" and "low jumpers" differed significantly (CMJ: 45.1 ± 2.2 vs. 37.1 ± 3.9 cm, respectively, p = 0.001). Countermovement jump was increased only in the "high jumpers" group by 5.4 ± 1.4% (p = 0.001) and 7.4 ± 1.2% (p = 0.001) at the knee angles of 90 and 140°, respectively. This improvement was larger at the 140° angle (p = 0.049). Knee angle during isometric squats and vertical jumping ability are important determinants of the acute CMJ performance increase observed after a conditioning activity.
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Affiliation(s)
- Athanasios Tsoukos
- Athletics Laboratory, Faculty of Physical Education and Sports Science, University of Athens, Greece
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25
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Lower fatigability of locomotor than non-locomotor muscles in endurance runners. SPORT SCIENCES FOR HEALTH 2016. [DOI: 10.1007/s11332-016-0297-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Neyroud D, Kayser B, Place N. Are There Critical Fatigue Thresholds? Aggregated vs. Individual Data. Front Physiol 2016; 7:376. [PMID: 27630575 PMCID: PMC5005398 DOI: 10.3389/fphys.2016.00376] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 08/15/2016] [Indexed: 12/16/2022] Open
Abstract
The mechanisms underlying task failure from fatiguing physical efforts have been the focus of many studies without reaching consensus. An attractive but debated model explains effort termination with a critical peripheral fatigue threshold. Upon reaching this threshold, feedback from sensory afferents would trigger task disengagement from open-ended tasks or a reduction of exercise intensity of closed-ended tasks. Alternatively, the extant literature also appears compatible with a more global critical threshold of loss of maximal voluntary contraction force. Indeed, maximal voluntary contraction force loss from fatiguing exercise realized at a given intensity appears rather consistent between different studies. However, when looking at individual data, the similar maximal force losses observed between different tasks performed at similar intensities might just be an “artifact” of data aggregation. It would then seem possible that such a difference observed between individual and aggregated data also applies to other models previously proposed to explain task failure from fatiguing physical efforts. We therefore suggest that one should be cautious when trying to infer models that try to explain individual behavior from aggregated data.
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Affiliation(s)
- Daria Neyroud
- Institute of Sport Sciences, University of LausanneLausanne, Switzerland; Department of Physiology, Faculty of Biology and Medicine, University of LausanneLausanne, Switzerland
| | - Bengt Kayser
- Institute of Sport Sciences, University of LausanneLausanne, Switzerland; Department of Physiology, Faculty of Biology and Medicine, University of LausanneLausanne, Switzerland
| | - Nicolas Place
- Institute of Sport Sciences, University of LausanneLausanne, Switzerland; Department of Physiology, Faculty of Biology and Medicine, University of LausanneLausanne, Switzerland
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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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Trezise J, Collier N, Blazevich AJ. Anatomical and neuromuscular variables strongly predict maximum knee extension torque in healthy men. Eur J Appl Physiol 2016; 116:1159-77. [PMID: 27076217 DOI: 10.1007/s00421-016-3352-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 03/02/2016] [Indexed: 11/29/2022]
Abstract
PURPOSE This study examined the relative influence of anatomical and neuromuscular variables on maximal isometric and concentric knee extensor torque and provided a comparative dataset for healthy young males. METHODS Quadriceps cross-sectional area (CSA) and fascicle length (l f) and angle (θ f) from the four quadriceps components; agonist (EMG:M) and antagonist muscle activity, and percent voluntary activation (%VA); patellar tendon moment arm distance (MA) and maximal voluntary isometric and concentric (60° s(-1)) torques, were measured in 56 men. Linear regression models predicting maximum torque were ranked using Akaike's Information Criterion (AICc), and Pearson's correlation coefficients assessed relationships between variables. RESULTS The best-fit models explained up to 72 % of the variance in maximal voluntary knee extension torque. The combination of 'CSA + θ f + EMG:M + %VA' best predicted maximum isometric torque (R (2) = 72 %, AICc weight = 0.38) and 'CSA + θ f + MA' (R (2) = 65 %, AICc weight = 0.21) best predicted maximum concentric torque. CONCLUSION Proximal quadriceps CSA was included in all models rather than the traditionally used mid-muscle CSA. Fascicle angle appeared consistently in all models despite its weak correlation with maximum torque in isolation, emphasising the importance of examining interactions among variables. While muscle activity was important for torque prediction in both contraction modes, MA only strongly influenced maximal concentric torque. These models identify the main sources of inter-individual differences strongly influencing maximal knee extension torque production in healthy men. The comparative dataset allows the identification of potential variables to target (i.e. weaknesses) in individuals.
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Affiliation(s)
- J Trezise
- Centre of Exercise and Health Science, Edith Cowan University, Joondalup, Australia.
| | - N Collier
- Faculty of Sustainability, Leuphana University, Lüneburg, Germany
| | - A J Blazevich
- Centre of Exercise and Health Science, Edith Cowan University, Joondalup, Australia.,School of Exercise and Health Sciences, Centre for Exercise and Sport Science Research (CESSR), Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027, Australia
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Pageaux B, Angius L, Hopker JG, Lepers R, Marcora SM. Central alterations of neuromuscular function and feedback from group III-IV muscle afferents following exhaustive high-intensity one-leg dynamic exercise. Am J Physiol Regul Integr Comp Physiol 2015; 308:R1008-20. [PMID: 25855308 DOI: 10.1152/ajpregu.00280.2014] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 04/07/2015] [Indexed: 11/22/2022]
Abstract
The aims of this investigation were to describe the central alterations of neuromuscular function induced by exhaustive high-intensity one-leg dynamic exercise (OLDE, study 1) and to indirectly quantify feedback from group III-IV muscle afferents via muscle occlusion (MO, study 2) in healthy adult male humans. We hypothesized that these central alterations and their recovery are associated with changes in afferent feedback. Both studies consisted of two time-to-exhaustion tests at 85% peak power output. In study 1, voluntary activation level (VAL), M-wave, cervicomedullary motor evoked potential (CMEP), motor evoked potential (MEP), and MEP cortical silent period (CSP) of the knee extensor muscles were measured. In study 2, mean arterial pressure (MAP) and leg muscle pain were measured during MO. Measurements were performed preexercise, at exhaustion, and after 3 min recovery. Compared with preexercise values, VAL was lower at exhaustion (-13 ± 13%, P < 0.05) and after 3 min of recovery (-6 ± 6%, P = 0.05). CMEP area/M area was lower at exhaustion (-38 ± 13%, P < 0.01) and recovered after 3 min. MEP area/M area was higher at exhaustion (+25 ± 27%, P < 0.01) and after 3 min of recovery (+17 ± 20%, P < 0.01). CSP was higher (+19 ± 9%, P < 0.01) only at exhaustion and recovered after 3 min. Markers of afferent feedback (MAP and leg muscle pain during MO) were significantly higher only at exhaustion. These findings suggest that the alterations in spinal excitability and CSP induced by high-intensity OLDE are associated with an increase in afferent feedback at exhaustion, whereas central fatigue does not fully recover even when significant afferent feedback is no longer present.
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Affiliation(s)
- Benjamin Pageaux
- Endurance Research Group, School of Sport & Exercise Sciences, University of Kent, Chatham, United Kingdom; and
| | - Luca Angius
- Endurance Research Group, School of Sport & Exercise Sciences, University of Kent, Chatham, United Kingdom; and
| | - James G Hopker
- Endurance Research Group, School of Sport & Exercise Sciences, University of Kent, Chatham, United Kingdom; and
| | - Romuald Lepers
- Laboratoire Institut national de la santé et de la recherche médical U1093, Université de Bourgogne, Faculté des Sciences du Sports, UFR STAPS, Dijon, France
| | - Samuele M Marcora
- Endurance Research Group, School of Sport & Exercise Sciences, University of Kent, Chatham, United Kingdom; and
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Matkowski B, Lepers R, Martin A. Torque decrease during submaximal evoked contractions of the quadriceps muscle is linked not only to muscle fatigue. J Appl Physiol (1985) 2015; 118:1136-44. [PMID: 25767032 DOI: 10.1152/japplphysiol.00553.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 03/06/2015] [Indexed: 11/22/2022] Open
Abstract
The aim of this study was to analyze the neuromuscular mechanisms involved in the torque decrease induced by submaximal electromyostimulation (EMS) of the quadriceps muscle. It was hypothesized that torque decrease after EMS would reflect the fatigability of the activated motor units (MUs), but also a reduction in the number of MUs recruited as a result of changes in axonal excitability threshold. Two experiments were performed on 20 men to analyze 1) the supramaximal twitch superimposed and evoked at rest during EMS (Experiment 1, n = 9) and 2) the twitch response and torque-frequency relation of the MUs activated by EMS (Experiment 2, n = 11). Torque loss was assessed by 15 EMS-evoked contractions (50 Hz; 6 s on/6 s off), elicited at a constant intensity that evoked 20% of the maximal voluntary contraction (MVC) torque. The same stimulation intensity delivered over the muscles was used to induce the torque-frequency relation and the single electrical pulse evoked after each EMS contraction (Experiment 2). In Experiment 1, supramaximal twitch was induced by femoral nerve stimulation. Torque decreased by ~60% during EMS-evoked contractions and by only ~18% during MVCs. This was accompanied by a rightward shift of the torque-frequency relation of MUs activated and an increase of the ratio between the superimposed and posttetanic maximal twitch evoked during EMS contraction. These findings suggest that the torque decrease observed during submaximal EMS-evoked contractions involved muscular mechanisms but also a reduction in the number of MUs recruited due to changes in axonal excitability.
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Affiliation(s)
- Boris Matkowski
- Laboratoire INSERM U1093, Cognition, Action et Plasticité Sensorimotrice, Université de Bourgogne, Faculté des Sciences du Sport, Dijon, France
| | - Romuald Lepers
- Laboratoire INSERM U1093, Cognition, Action et Plasticité Sensorimotrice, Université de Bourgogne, Faculté des Sciences du Sport, Dijon, France
| | - Alain Martin
- Laboratoire INSERM U1093, Cognition, Action et Plasticité Sensorimotrice, Université de Bourgogne, Faculté des Sciences du Sport, Dijon, France
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Pageaux B, Marcora SM, Rozand V, Lepers R. Mental fatigue induced by prolonged self-regulation does not exacerbate central fatigue during subsequent whole-body endurance exercise. Front Hum Neurosci 2015; 9:67. [PMID: 25762914 PMCID: PMC4340216 DOI: 10.3389/fnhum.2015.00067] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 01/27/2015] [Indexed: 11/26/2022] Open
Abstract
It has been shown that the mental fatigue induced by prolonged self-regulation increases perception of effort and reduces performance during subsequent endurance exercise. However, the physiological mechanisms underlying these negative effects of mental fatigue are unclear. The primary aim of this study was to test the hypothesis that mental fatigue exacerbates central fatigue induced by whole-body endurance exercise. Twelve subjects performed 30 min of either an incongruent Stroop task to induce a condition of mental fatigue or a congruent Stroop task (control condition) in a random and counterbalanced order. Both cognitive tasks (CTs) were followed by a whole-body endurance task (ET) consisting of 6 min of cycling exercise at 80% of peak power output measured during a preliminary incremental test. Neuromuscular function of the knee extensors was assessed before and after CT, and after ET. Rating of perceived exertion (RPE) was measured during ET. Both CTs did not induce any decrease in maximal voluntary contraction (MVC) torque (p = 0.194). During ET, mentally fatigued subjects reported higher RPE (mental fatigue 13.9 ± 3.0, control 13.3 ± 3.2, p = 0.044). ET induced a similar decrease in MVC torque (mental fatigue -17 ± 15%, control -15 ± 11%, p = 0.001), maximal voluntary activation level (mental fatigue -6 ± 9%, control -6 ± 7%, p = 0.013) and resting twitch (mental fatigue -30 ± 14%, control -32 ± 10%, p < 0.001) in both conditions. These findings reject our hypothesis and confirm previous findings that mental fatigue does not reduce the capacity of the central nervous system to recruit the working muscles. The negative effect of mental fatigue on perception of effort does not reflect a greater development of either central or peripheral fatigue. Consequently, mentally fatigued subjects are still able to perform maximal exercise, but they are experiencing an altered performance during submaximal exercise due to higher-than-normal perception of effort.
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Affiliation(s)
- Benjamin Pageaux
- Endurance Research Group, School of Sport & Exercise Sciences, University of Kent at MedwayChatham Maritime, UK
- Laboratoire INSERM U1093, Faculté des Sciences du Sports – UFR Staps, Université de BourgogneDijon, France
| | - Samuele M. Marcora
- Endurance Research Group, School of Sport & Exercise Sciences, University of Kent at MedwayChatham Maritime, UK
| | - Vianney Rozand
- Laboratoire INSERM U1093, Faculté des Sciences du Sports – UFR Staps, Université de BourgogneDijon, France
| | - Romuald Lepers
- Laboratoire INSERM U1093, Faculté des Sciences du Sports – UFR Staps, Université de BourgogneDijon, France
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Rozand V, Pageaux B, Marcora SM, Papaxanthis C, Lepers R. Does mental exertion alter maximal muscle activation? Front Hum Neurosci 2014; 8:755. [PMID: 25309404 PMCID: PMC4176059 DOI: 10.3389/fnhum.2014.00755] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/08/2014] [Indexed: 11/23/2022] Open
Abstract
Mental exertion is known to impair endurance performance, but its effects on neuromuscular function remain unclear. The purpose of this study was to test the hypothesis that mental exertion reduces torque and muscle activation during intermittent maximal voluntary contractions of the knee extensors. Ten subjects performed in a randomized order three separate mental exertion conditions lasting 27 min each: (i) high mental exertion (incongruent Stroop task), (ii) moderate mental exertion (congruent Stroop task), (iii) low mental exertion (watching a movie). In each condition, mental exertion was combined with 10 intermittent maximal voluntary contractions of the knee extensor muscles (one maximal voluntary contraction every 3 min). Neuromuscular function was assessed using electrical nerve stimulation. Maximal voluntary torque, maximal muscle activation and other neuromuscular parameters were similar across mental exertion conditions and did not change over time. These findings suggest that mental exertion does not affect neuromuscular function during intermittent maximal voluntary contractions of the knee extensors.
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Affiliation(s)
- Vianney Rozand
- Institut National de la Santé et de la Recherche Médicale U1093, Faculty of Sport Sciences, University of Burgundy Dijon, France
| | - Benjamin Pageaux
- Institut National de la Santé et de la Recherche Médicale U1093, Faculty of Sport Sciences, University of Burgundy Dijon, France ; Endurance Research Group, School of Sport and Exercise Sciences, University of Kent at Medway Chatham Maritime, UK
| | - Samuele M Marcora
- Endurance Research Group, School of Sport and Exercise Sciences, University of Kent at Medway Chatham Maritime, UK
| | - Charalambos Papaxanthis
- Institut National de la Santé et de la Recherche Médicale U1093, Faculty of Sport Sciences, University of Burgundy Dijon, France
| | - Romuald Lepers
- Institut National de la Santé et de la Recherche Médicale U1093, Faculty of Sport Sciences, University of Burgundy Dijon, France
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Pageaux B, Marcora SM, Lepers R. Prolonged mental exertion does not alter neuromuscular function of the knee extensors. Med Sci Sports Exerc 2014; 45:2254-64. [PMID: 23698244 DOI: 10.1249/mss.0b013e31829b504a] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The aim of this study was to test the hypotheses that prolonged mental exertion (i) reduces maximal muscle activation and (ii) increases the extent of central fatigue induced by subsequent endurance exercise. METHODS The neuromuscular function of the knee extensor muscles was assessed in 10 male subjects in two different conditions: (i) before and after prolonged mental exertion leading to mental fatigue and (ii) before and after an easy cognitive task (control). Both cognitive tasks lasted 90 min and were followed by submaximal isometric knee extensor exercise until exhaustion (endurance task), and a third assessment of neuromuscular function. RESULTS Time to exhaustion was 13% ± 4% shorter in the mental fatigue condition (230 ± 22 s) compared with the control condition (266 ± 26 s) (P < 0.01). Prolonged mental exertion did not have any significant effect on maximal voluntary contraction torque, voluntary activation level, and peripheral parameters of neuromuscular function. A similar significant decrease in maximal voluntary contraction torque (mental fatigue condition: -26.7% ± 5.7%; control condition: -27.6% ± 3.3%, P < 0.001), voluntary activation level (mental fatigue: -10.6% ± 4.3%; control condition: -11.2% ± 5.2%, P < 0.05), and peripheral parameters of neuromuscular function occurred in both conditions after the endurance task. However, mentally fatigued subjects rated perceived exertion significantly higher during the endurance task compared with the control condition (P < 0.05). CONCLUSIONS These findings provide the first experimental evidence that prolonged mental exertion (i) does not reduce maximal muscle activation and (ii) does not increase the extent of central fatigue induced by subsequent endurance exercise. The negative effect of mental fatigue on endurance performance seems to be mediated by the higher perception of effort rather than impaired neuromuscular function.
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Affiliation(s)
- Benjamin Pageaux
- 1Endurance Research Group, School of Sport & Exercise Sciences, University of Kent at Medway, Chatham Maritime, Kent, UNITED KINGDOM; and 2Laboratoire INSERM U1093, Université de Bourgogne, Faculté des Sciences du Sports-UFR STAPS, Dijon, FRANCE
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Boullosa DA, Abreu L, Beltrame LGN, Behm DG. The acute effect of different half squat set configurations on jump potentiation. J Strength Cond Res 2014. [PMID: 23207892 DOI: 10.1519/jsc.0b013e31827ddf15] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The aim of this study was to evaluate the acute effect of a half squat exercise performed with different set configurations on jump potentiation. Twelve resistance-trained men were evaluated on 3 occasions separated by 48-96 hours. First, they performed a 5 repetitions maximum (5RM) test. Subsequently, they performed in a randomized order 2 sessions: one session with 5RM until failure and the other with the same workload but with 30-second rest intervals between repetitions (i.e., cluster set [CS]). Countermovement jump performance was examined during the second and third sessions for jump height and force-time parameters using a force platform at the following time intervals: before and at 1, 3, 6, 9, and 12 minutes. Separate comparisons for each variable at the different time intervals were analyzed using analysis of variance, effect size, and qualitative inferences. The majority of the parameters improved independently of the time they occurred, except for peak force and vertical stiffness after a set until failure. For peak power, it appears that the cluster treatment resulted in superior potentiation at 1 minute, whereas the 5RM treatment resulted in greater potentiation at 9 minutes. Effect size analysis and qualitative outcomes revealed an improvement in vertical stiffness and a lowering in the depth of the countermovement in CS. There were significant correlations between participants' 5RM relative performance and various force-time parameters only in CS. It appears that a CS induces greater peak power than a 5RM set at 1 minute, although the reverse occurs at 9 minutes. Delayed potentiation associated with the 5RM may be attributed to greater fatigue versus the CS approach. Therefore, it follows that the optimal method for inducing peak power potentiation is dependent on the available time between heavy half squat exercise and the subsequent jump performance.
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Affiliation(s)
- Daniel A Boullosa
- Post-Graduate Program in Physical Education, Catholic University of Brasilia, Brasilia, Brazil.
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Olson MW. Comparison of trunk muscle reflex activation patterns between active and passive trunk flexion-extension loading conditions. Hum Mov Sci 2014; 34:12-27. [PMID: 24690742 DOI: 10.1016/j.humov.2014.03.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 03/01/2014] [Accepted: 03/07/2014] [Indexed: 11/30/2022]
Abstract
The aim of the present study was to determine the effects of trunk flexion-extension loading on the neuromuscular reflexive latencies and amplitude responses of the trunk musculature. Eighteen male and female subjects (18-27yrs) participated in active and passive trunk flexion extension, performed ∼7days apart. Subjects performed 60 trunk flexion-extension repetitions. Surface electromyography (EMG) was collected bilaterally from paraspinal and abdominal muscles. In the active condition, subjects volitionally moved their trunks, while in the passive condition the dynamometer controlled the movements. The trunk was perturbed before and immediately after 30 repetitions. Latency of muscle onset, latency of first peak, latency of maximum peak, and peak EMG amplitude were evaluated. No differences between conditions, sides, or perturbation session were apparent. Overall latencies were shorter in females (p<.05) and abdominal muscles compared to paraspinals (p<.05). Thoracic paraspinal muscle amplitudes were greater than all other muscles (p<.05). Based upon the present results, the neuromuscular system engages trunk flexor muscles prior to the paraspinals in order to provide possible stabilization of the trunk when flexor moments are generated. Overall, the results indicate no difference in response of the neuromuscular system to active or passive repetitive loading.
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Affiliation(s)
- Michael W Olson
- Southern Illinois University, Department of Kinesiology, 1075 S. Normal Avenue, Carbondale, IL 62901, United States.
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Neyroud D, Vallotton A, Millet GY, Kayser B, Place N. The effect of muscle fatigue on stimulus intensity requirements for central and peripheral fatigue quantification. Eur J Appl Physiol 2013; 114:205-15. [PMID: 24197080 DOI: 10.1007/s00421-013-2760-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 10/21/2013] [Indexed: 12/20/2022]
Abstract
PURPOSE The present study was designed to determine the stimulation intensity necessary for an adequate assessment of central and peripheral components of neuromuscular fatigue of the knee extensors. METHODS Three different stimulation intensities (100, 120 and 150% of the lowest intensity evoking a plateau in M-waves and twitch amplitudes, optimal stimulation intensity, OSI) were used to assess voluntary activation level (VAL) as well as M-wave, twitch and doublet amplitudes before, during and after an incremental isometric exercise performed by 14 (8 men) healthy and physically active volunteers. A visual analog scale was used to evaluate the associated discomfort. RESULTS There was no difference (p > 0.05) in VAL between the three intensities before and after exercise. However, we found that stimulating at 100% OSI may overestimate the extent of peripheral fatigue during exercise, whereas 150% OSI stimulations led to greater discomfort associated with doublet stimulations as well as to an increased antagonist co-activation compared to 100% OSI. CONCLUSION We recommend using 120% OSI, as it constitutes a good trade-off between discomfort and reliable measurements.
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Affiliation(s)
- Daria Neyroud
- Institute of Movement Sciences and Sports Medicine, University of Geneva, Geneva, Switzerland
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Abstract
Skeletal muscle fatigue is defined as the fall of force or power in response to contractile activity. Both the mechanisms of fatigue and the modes used to elicit it vary tremendously. Conceptual and technological advances allow the examination of fatigue from the level of the single molecule to the intact organism. Evaluation of muscle fatigue in a wide range of disease states builds on our understanding of basic function by revealing the sources of dysfunction in response to disease.
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Affiliation(s)
- Jane A Kent-Braun
- Department of Kinesiology, University of Massachusetts-Amherst, Amherst, Massachusetts, USA.
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Rodriguez-Falces J, Maffiuletti NA, Place N. Twitch and M-wave potentiation induced by intermittent maximal voluntary quadriceps contractions: differences between direct quadriceps and femoral nerve stimulation. Muscle Nerve 2013; 48:920-9. [PMID: 23536413 DOI: 10.1002/mus.23856] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2013] [Indexed: 11/12/2022]
Abstract
INTRODUCTION The aim of this study was to investigate differences in twitch and M-wave potentiation in the quadriceps femoris when electrical stimulation is applied over the quadriceps muscle belly versus the femoral nerve trunk. METHODS M-waves and mechanical twitches were evoked using direct quadriceps muscle and femoral nerve stimulation between 48 successive isometric maximal voluntary contractions (MVC) from 10 young, healthy subjects. Potentiation was investigated by analyzing the changes in M-wave amplitude recorded from the vastus medialis (VM) and vastus lateralis (VL) muscles and in quadriceps peak twitch force. RESULTS Potentiation of twitch, VM M-wave, and VL M-wave were greater for femoral nerve than for direct quadriceps stimulation (P < 0.05). Despite a 50% decrease in MVC force, the amplitude of the M-waves increased significantly during exercise. CONCLUSIONS In addition to enhanced electrogenic Na(+) -K(+) pumping, other factors (such as synchronization in activation of muscle fibers and muscle architectural properties) may significantly influence the magnitude of M-wave enlargement.
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Affiliation(s)
- Javier Rodriguez-Falces
- Department of Electrical and Electronic Engineering, Universidad Pública de Navarra DIEE, Campus de Arrosadía s/n, 31006, Pamplona, Spain
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Neyroud D, Rüttimann J, Mannion AF, Millet GY, Maffiuletti NA, Kayser B, Place N. Comparison of neuromuscular adjustments associated with sustained isometric contractions of four different muscle groups. J Appl Physiol (1985) 2013; 114:1426-34. [DOI: 10.1152/japplphysiol.01539.2012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The extent and characteristics of muscle fatigue of different muscle groups when subjected to a similar fatiguing task may differ. Thirteen healthy young men performed sustained contractions at 50% maximal voluntary contraction (MVC) force until task failure, with four different muscle groups, over two sessions. Per session, one upper limb and one lower limb muscle group were tested (knee extensors and thumb adductor, or plantar and elbow flexors). Changes in voluntary activation level and contractile properties were derived from doublet responses evoked during and after MVCs before and after exercise. Time to task failure differed ( P < 0.05) between muscle groups (220 ± 64 s for plantar flexors, 114 ± 27 s for thumb adductor, 77 ± 25 s for knee extensors, and 72 ± 14 s for elbow flexors). MVC force loss immediately after voluntary task failure was similar (−30 ± 11% for plantar flexors, −37 ± 13% for thumb adductor, −34 ± 15% for knee extensors, and −40 ± 12% for elbow flexors, P > 0.05). Voluntary activation was decreased for plantar flexors only (from 95 ± 5% to 82 ± 9%, P < 0.05). Potentiated evoked doublet amplitude was more depressed for upper limb muscles (−59.3 ± 14.7% for elbow flexors and −60.1 ± 24.1% for thumb adductor, P < 0.05) than for knee extensors (−28 ± 15%, P < 0.05); no reduction was found in plantar flexors (−7 ± 12%, P > 0.05). In conclusion, despite different times to task failure when sustaining an isometric contraction at 50% MVC force for as long as possible, diverse muscle groups present similar loss of MVC force after task failure. Thus the extent of muscle fatigue is not affected by time to task failure, whereas this latter determines the etiology of fatigue.
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Affiliation(s)
- Daria Neyroud
- Institute of Movement Sciences and Sports Medicine, University of Geneva, Geneva, Switzerland
| | - Jennifer Rüttimann
- Institute of Movement Sciences and Sports Medicine, University of Geneva, Geneva, Switzerland
| | | | | | | | - Bengt Kayser
- Institute of Movement Sciences and Sports Medicine, University of Geneva, Geneva, Switzerland
| | - Nicolas Place
- Institute of Movement Sciences and Sports Medicine, University of Geneva, Geneva, Switzerland
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Divergent muscle fatigue during unilateral isometric contractions of dominant and non-dominant quadriceps. J Sci Med Sport 2013; 16:240-4. [DOI: 10.1016/j.jsams.2012.06.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 03/30/2012] [Accepted: 06/16/2012] [Indexed: 11/24/2022]
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Neyroud D, Maffiuletti NA, Kayser B, Place N. Mechanisms of fatigue and task failure induced by sustained submaximal contractions. Med Sci Sports Exerc 2012; 44:1243-51. [PMID: 22215181 DOI: 10.1249/mss.0b013e318245cc4d] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The present study was designed to investigate whether central neural mechanisms limit the duration of a sustained low-force isometric contraction and the maximal force-generating capacity of the knee extensors. METHODS Fourteen healthy males (28 ± 7 yr) were asked to sustain, until voluntary exhaustion, an isometric contraction with their right knee extensor muscles at a target force equal to 20% of their maximal voluntary contraction (MVC) force. At task failure, the muscle was immediately electrically stimulated for 1 min aiming the same target force (20% MVC force). Subsequently, subjects were asked to resume the voluntary contraction for as long as possible. Knee extensor neuromuscular function was assessed before and after the entire protocol for comparison. RESULTS When electrically stimulated at the point of task failure, all subjects developed the 20% MVC force target, indicating that lack of force-generating capacity from peripheral impairment had not limited the duration of the first task. We observed a reduction in MVC force after the entire protocol (-57% ± 12%), which correlated with a decrease in potentiated peak doublet force (-48% ± 17%, P < 0.001). The level of voluntary activation, as quantified with the interpolated twitch technique, was slightly depressed after the entire protocol (from 93% ± 7% to 87% ± 10%, P < 0.01). CONCLUSIONS It follows that task failure from a sustained isometric contraction is mainly affected by central/motivational factors, whereas MVC force loss is largely explained by the extent of contractile failure of the muscle.
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Affiliation(s)
- Daria Neyroud
- Institute of Movement Sciences and Sports Medicine, University of Geneva, Geneva, Switzerland
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Matkowski B, Place N, Martin A, Lepers R. Neuromuscular fatigue differs following unilateral vs bilateral sustained submaximal contractions. Scand J Med Sci Sports 2011; 21:268-76. [PMID: 19903318 DOI: 10.1111/j.1600-0838.2009.01040.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The purpose of the present study was to compare the mechanisms of fatigue induced by a unilateral vs a bilateral submaximal isometric knee extension. Ten physically active men completed two experimental sessions, randomly presented. They were asked to maintain an isometric knee extension force corresponding to 20% of the maximal voluntary contraction (MVC) until task failure with one leg (unilateral) vs two legs (bilateral). MVCs were performed before and after the sustained contraction. Transcutaneous electrical stimuli were used to examine central (voluntary activation) and peripheral (peak doublet force at rest) fatigue on the exercised leg. Time to task failure was significantly shorter (P<0.05) for the bilateral (245 ± 76 s) compared with the unilateral task (295 ± 85 s). Unilateral MVC force and maximal voluntary activation losses were significantly greater (P<0.05) after the unilateral task than after the bilateral task. Peak doublet force was significantly reduced (P<0.01) after the unilateral task, but not after the bilateral task. The present results demonstrated that time to task failure of a submaximal fatiguing contraction may depend on the number of limbs involved in the task. The greater time to task failure with one leg may have induced greater contractile alterations and a larger MVC loss following the unilateral task.
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Affiliation(s)
- B Matkowski
- INSERM U887, Université de Bourgogne, Dijon, France.
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Crewther BT, Cook CJ, Lowe TE, Weatherby RP, Gill N. The effects of short-cycle sprints on power, strength, and salivary hormones in elite rugby players. J Strength Cond Res 2011; 25:32-9. [PMID: 20093968 DOI: 10.1519/jsc.0b013e3181b6045c] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study examined the effects of short-cycle sprints on power, strength, and salivary hormones in elite rugby players. Thirty male rugby players performed an upper-body power and lower-body strength (UPLS) and/or a lower-body power and upper-body strength (LPUS) workout using a crossover design (sprint vs. control). A 40-second upper-body or lower-body cycle sprint was performed before the UPLS and LPUS workouts, respectively, with the control sessions performed without the sprints. Bench throw (BT) power and box squat (BS) 1 repetition maximum (1RM) strength were assessed in the UPLS workout, and squat jump (SJ) power and bench press (BP) 1RM strength were assessed in the LPUS workout. Saliva was collected across each workout and assayed for testosterone (Sal-T) and cortisol (Sal-C). The cycle sprints improved BS (2.6 ± 1.2%) and BP (2.8 ± 1.0%) 1RM but did not affect BT and SJ power. The lower-body cycle sprint produced a favorable environment for the BS by elevating Sal-T concentrations. The upper-body cycle sprint had no hormonal effect, but the workout differences (%) in Sal-T (r = -0.59) and Sal-C (r = 0.42) concentrations correlated to the BP, along with the Sal-T/C ratio (r = -0.49 to -0.66). In conclusion, the cycle sprints improved the BP and BS 1RM strength of elite rugby players but not power output in the current format. The improvements noted may be explained, in part, by the changes in absolute or relative hormone concentrations. These findings have practical implications for prescribing warm-up and training exercises.
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Affiliation(s)
- Blair T Crewther
- Health and Food Group, The Horticulture and Food Research Institute of New Zealand, Hamilton, New Zealand.
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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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Smilios I, Häkkinen K, Tokmakidis SP. Power output and electromyographic activity during and after a moderate load muscular endurance session. J Strength Cond Res 2010; 24:2122-31. [PMID: 19834352 DOI: 10.1519/jsc.0b013e3181a5bc44] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The purpose of this study was to examine (a) the mechanical power and the electromyographic (EMG) activity during a moderate load muscular endurance session and (b) the maximal mechanical power output and EMG activity using a light load and a heavy load afterward. Sixteen men (age: 20.7 +/- 1.1 years) performed 4 sets of 20 repetitions with an initial load of 50% of 1 repetition maximum (1RM), and 2 minutes of rest, in the squat exercise. Furthermore, the subjects performed 4 repetitions with loads of 40 and 80% of 1RM before, immediately after, and 30 minutes after the end of the session. Average power and EMG activity from vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF) were recorded during the concentric phase of the lift. Average power did not change during the first 2 sets, while it decreased (p < 0.05) during the third and the fourth set. Average quadriceps (AQ), VM, VL, and RF activity increased (p < 0.05) until the 11th repetition, approximately, during each set while it increased gradually from set to set. Maximal power and AQ, VM, and VL activity with the loads of 40 and 80% of 1RM were decreased (p < 0.05) after the session. Blood lactate reached 10.2 +/- 2.5 and 13.1 +/- 4.1 mmolxL after the second and the fourth set, respectively. It appears that during a muscular endurance session with submaximal power output, mechanical performance may gradually decrease, probably due to metabolic fatigue, while muscle electrical activity may increase. Following this type of a session, maximal power output and muscle activation with a light and especially with a heavy load are reduced.
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Affiliation(s)
- Ilias Smilios
- Department of Physical Education and Sport Science, Democritus University of Thrace, Komotini, Greece.
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Hostettler S, Illi SK, Mohler E, Aliverti A, Spengler CM. Chest wall volume changes during inspiratory loaded breathing. Respir Physiol Neurobiol 2010; 175:130-9. [PMID: 20937414 DOI: 10.1016/j.resp.2010.10.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 09/09/2010] [Accepted: 10/04/2010] [Indexed: 11/15/2022]
Abstract
We assessed the effect of inspiratory loaded breathing (ILB) on respiratory muscle strength and investigated the extent to which respiratory muscle fatigue is associated with chest wall volume changes during ILB. Twelve healthy subjects performed ILB at 76 ± 11% of maximal inspiratory mouth pressure (MIP) for 1h. MIP and breathing pattern during 3 min of normocapnic hyperpnea (NH) were measured before and after ILB. Breathing pattern and chest wall volume changes were assessed by optoelectronic plethysmography. After ILB, six subjects decreased MIP significantly (-16 ± 10%; p < 0.05), while the other six subjects did not (0 ± 7%, p = 0.916). Only subjects with decreased MIP after ILB lowered end-expiratory rib cage volume (volume at which inspiration is initiated) below resting values during ILB. During NH after ILB, tidal volume was smaller in subjects with decreased MIP (-19 ± 16%, p < 0.05), while it remained unchanged in the other group (-3 ± 11%, p = 0.463). These results suggest that respiratory muscle fatigue depends on the lung volume from which inspiratory efforts are made during ILB.
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Affiliation(s)
- Stefanie Hostettler
- Exercise Physiology, Institute of Human Movement Sciences, ETH Zurich, Zurich, Switzerland.
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Quadriceps activation following aerobic exercise in persons with low back pain and healthy controls. Clin Biomech (Bristol, Avon) 2010; 25:847-51. [PMID: 20566233 DOI: 10.1016/j.clinbiomech.2010.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 02/03/2010] [Accepted: 05/18/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND A relationship between the muscles that stabilize the lumbar spine and the lower extremity exists that may result in neuromuscular and biomechanical changes during prolonged aerobic exercise in those with low back pain. METHODS Twenty recreationally active adults with healthy lower extremity joints, 7 with recurring episodes of low back pain performed a standard 15-minute aerobic exercise protocol on a treadmill. Quadriceps torque during a maximal isometric voluntary contraction, quadriceps central activation ratio and superimposed burst torque as measured with the superimposed burst technique, and vastus lateralis median frequency were recorded before and after treadmill exercise. A burst of electrical stimuli was superimposed during maximal knee extension causing a transient increase in torque. Quadriceps central activation was calculated as the ratio between maximal volitional and superimposed burst torques. We recorded vastus lateralis surface Electromyography (EMG) during knee extension contractions and calculated the median frequency. FINDINGS We observed a 12.4% reduction in the quadriceps central activation ratio after aerobic exercise in participants with recurrent low back pain; healthy controls only experienced a 1.7% reduction. There was no change in quadriceps median frequency following aerobic exercise. INTERPRETATION Deteriorated quadriceps function following aerobic exercise was observed in patients with recurrent episodes of low back pain who had healthy knee joints. This reduction is mediated by a central process that may arise from poor strength and endurance in the muscles surrounding the spine, which is common in persons with recurrent low back pain.
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Place N, Yamada T, Bruton JD, Westerblad H. Muscle fatigue: from observations in humans to underlying mechanisms studied in intact single muscle fibres. Eur J Appl Physiol 2010; 110:1-15. [DOI: 10.1007/s00421-010-1480-0] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2010] [Indexed: 01/01/2023]
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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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Law LAF, Avin KG. Endurance time is joint-specific: a modelling and meta-analysis investigation. ERGONOMICS 2010; 53:109-29. [PMID: 20069487 PMCID: PMC2891087 DOI: 10.1080/00140130903389068] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Static task intensity-endurance time (ET) relationships (e.g. Rohmert's curve) were first reported decades ago. However, a comprehensive meta-analysis to compare experimentally-observed ETs across bodily regions has not been reported. We performed a systematic literature review of ETs for static contractions, developed joint-specific power and exponential models of the intensity-ET relationships, and compared these models between each joint (ankle, trunk, hand/grip, elbow, knee, and shoulder) and the pooled data (generalised curve). 194 publications were found, representing a total of 369 data points. The power model provided the best fit to the experimental data. Significant intensity-dependent ET differences were predicted between each pair of joints. Overall, the ankle was most fatigue-resistant, followed by the trunk, hand/grip, elbow, knee and finally the shoulder was most fatigable. We conclude ET varies systematically between joints, in some cases with large effect sizes. Thus, a single generalised ET model does not adequately represent fatigue across joints. STATEMENT OF RELEVANCE: Rohmert curves have been used in ergonomic analyses of fatigue, as there are limited tools available to accurately predict force decrements. This study provides updated endurance time-intensity curves using a large meta-analysis of fatigue data. Specific models derived for five distinct joint regions should further increase prediction accuracy.
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