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Characterization of performance fatigability during a self-paced exercise.
J Appl Physiol (1985). 2019 09 01; 127(3):838-846.JA

Abstract

Pacing during a high-intensity cycling time trial (TT) appears to prevent premature task failure, but the performance fatigability during a self-paced exercise is currently unknown. Therefore, the current study characterized the time course of performance fatigability during a 4-km TT. Eleven male cyclists performed three separated TTs in a crossover, counterbalanced design. The TTs lasted until the end of the fast-start (FS; 600 ± 205 m), even-pace (EP; 3,600 ± 190 m), and end-spurt (ES; 4,000 m) phases. Performance fatigability was characterized by using isometric maximal voluntary contractions (IMVCs), whereas the muscle activation [i.e., voluntary activation (VA)] and contractile function of knee extensors [e.g., peak torque of potentiated twitches (TwPt)] were evaluated using electrically evoked contractions performed before and 1 min after each specific part of the trial. Gas exchange, power output (PO), and electromyographic activity (EMG) were also recorded. EMG/PO showed an abrupt increase followed by a continuous decrease toward the end of FS, resulting in a drop in IMVC (-12%), VA (-8%), and TwPt (-23%). EMG/PO was stable during EP, with no additional drop on IMVC, VA, or TwPt (-12%, -6%, and -22%, respectively). EMG/PO increased abruptly during the ES, but there was no change in IMVCs, VA, or TwPt (-13%, -8%, and -26%, respectively). These findings demonstrate that the performance fatigability during a self-paced exercise is characterized by a large drop in contractile function and muscle activation at the beginning of the trial (i.e., FS), without additional change during the middle and end phases (i.e., EP and ES).NEW & NOTEWORTHY The time course of performance fatigability throughout a self-paced exercise is currently unknown. The results showed that a large amount of muscle activation and contractile function impairments are attained early on a self-paced exercise (first ∼15% of the total time trial distance) and maintained throughout the test. This novel finding characterizes the performance fatigability from a contractile function and muscle activation perspective, which brings new insights for future studies focused on real-world exercise training and competition.

Authors+Show Affiliations

Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil. Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil.Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil.Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil. Sport Science Research Group, Academic Center of Vitória, Federal University of Pernambuco, Pernambuco, Brazil.Center of Engineering Modeling and Applied Social Science, Federal University of ABC, São Paulo, Brazil.Sport Science Research Group, Academic Center of Vitória, Federal University of Pernambuco, Pernambuco, Brazil. Human Performance Research Group, Technological Federal University of Paraná, Paraná, Brazil.Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

31318614

Citation

Azevedo, Rafael de Almeida, et al. "Characterization of Performance Fatigability During a Self-paced Exercise." Journal of Applied Physiology (Bethesda, Md. : 1985), vol. 127, no. 3, 2019, pp. 838-846.
Azevedo RA, Cruz R, Couto P, et al. Characterization of performance fatigability during a self-paced exercise. J Appl Physiol. 2019;127(3):838-846.
Azevedo, R. A., Cruz, R., Couto, P., Silva-Cavalcante, M. D., Boari, D., Lima-Silva, A. E., Millet, G. Y., & Bertuzzi, R. (2019). Characterization of performance fatigability during a self-paced exercise. Journal of Applied Physiology (Bethesda, Md. : 1985), 127(3), 838-846. https://doi.org/10.1152/japplphysiol.00090.2019
Azevedo RA, et al. Characterization of Performance Fatigability During a Self-paced Exercise. J Appl Physiol. 2019 09 1;127(3):838-846. PubMed PMID: 31318614.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Characterization of performance fatigability during a self-paced exercise. AU - Azevedo,Rafael de Almeida, AU - Cruz,Ramon, AU - Couto,Patrícia, AU - Silva-Cavalcante,Marcos David, AU - Boari,Daniel, AU - Lima-Silva,Adriano E, AU - Millet,Guillaume Y, AU - Bertuzzi,Romulo, Y1 - 2019/07/18/ PY - 2019/7/19/pubmed PY - 2019/7/19/medline PY - 2019/7/19/entrez KW - central fatigue KW - electromyography KW - exercise intensity domains KW - muscle recruitment KW - peripheral fatigue KW - power output SP - 838 EP - 846 JF - Journal of applied physiology (Bethesda, Md. : 1985) JO - J. Appl. Physiol. VL - 127 IS - 3 N2 - Pacing during a high-intensity cycling time trial (TT) appears to prevent premature task failure, but the performance fatigability during a self-paced exercise is currently unknown. Therefore, the current study characterized the time course of performance fatigability during a 4-km TT. Eleven male cyclists performed three separated TTs in a crossover, counterbalanced design. The TTs lasted until the end of the fast-start (FS; 600 ± 205 m), even-pace (EP; 3,600 ± 190 m), and end-spurt (ES; 4,000 m) phases. Performance fatigability was characterized by using isometric maximal voluntary contractions (IMVCs), whereas the muscle activation [i.e., voluntary activation (VA)] and contractile function of knee extensors [e.g., peak torque of potentiated twitches (TwPt)] were evaluated using electrically evoked contractions performed before and 1 min after each specific part of the trial. Gas exchange, power output (PO), and electromyographic activity (EMG) were also recorded. EMG/PO showed an abrupt increase followed by a continuous decrease toward the end of FS, resulting in a drop in IMVC (-12%), VA (-8%), and TwPt (-23%). EMG/PO was stable during EP, with no additional drop on IMVC, VA, or TwPt (-12%, -6%, and -22%, respectively). EMG/PO increased abruptly during the ES, but there was no change in IMVCs, VA, or TwPt (-13%, -8%, and -26%, respectively). These findings demonstrate that the performance fatigability during a self-paced exercise is characterized by a large drop in contractile function and muscle activation at the beginning of the trial (i.e., FS), without additional change during the middle and end phases (i.e., EP and ES).NEW & NOTEWORTHY The time course of performance fatigability throughout a self-paced exercise is currently unknown. The results showed that a large amount of muscle activation and contractile function impairments are attained early on a self-paced exercise (first ∼15% of the total time trial distance) and maintained throughout the test. This novel finding characterizes the performance fatigability from a contractile function and muscle activation perspective, which brings new insights for future studies focused on real-world exercise training and competition. SN - 1522-1601 UR - https://www.unboundmedicine.com/medline/citation/31318614/Characterization_of_performance_fatigability_during_a_self-paced_exercise L2 - http://journals.physiology.org/doi/full/10.1152/japplphysiol.00090.2019?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -
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