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Characterization of performance fatigability during a self-paced exercise.

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, 3600 ± 190 m) and end-spurt (ES, 4000 m) phases. Performance fatigability was characterized by using isometric maximal voluntary contractions (IMVC), while the muscle activation [i.e., voluntary activation (VA)] and contractile function of knee extensors [i.g., peak torque of potentiated twitches (TwPt)] were evaluated using electrically-evoked contractions performed (PRE) and 1 min after (POST) 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 towards the end of FS resulting in a drop on IMVC (-12%), VA (-8%) and TwPt (-23%). EMG/PO was stable during EP, with no additional drop on IMVC, VA and TwPt (-12%, -6% and -22%, respectively). EMG/PO increased abruptly during the ES, but there was no change on IMVC, VA and TwPt (-13%, -8% and -26%, respectively). These findings demonstrate that the performance fatigability during a self-paced exercise is characterized by a large drop on contractile function and muscle activation at beginning of the trial (i.e., FS), without additional change during the middle and end phases (i.e., EP and ES).

Authors+Show Affiliations

Faculty of Kinesiology, University of Calgary, Canada.Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo, Brazil.Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo, Brazil.Endurance Performance Research Group, School of Physical Education and Sport, University of Sao Paulo, Brazil.Center of Engineering Modeling and Applied Social Science, Federal University of ABC, Brazil.Academic Department of Physical Education, Technological Federal University of Parana, Brazil.Laboratorie Interuniversitaire de Biologe de la Motricite, Jean Monnet University Saint-Etienne, France.Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo.

Pub Type(s)

Journal Article

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), 2019.
Azevedo RA, Cruz R, Couto PG, et al. Characterization of performance fatigability during a self-paced exercise. J Appl Physiol. 2019.
Azevedo, R. A., Cruz, R., Couto, P. G., Silva-Cavalcante, M. D., Boari, D., Lima-Silva, A. E., ... Bertuzzi, R. (2019). Characterization of performance fatigability during a self-paced exercise. Journal of Applied Physiology (Bethesda, Md. : 1985), doi:10.1152/japplphysiol.00090.2019.
Azevedo RA, et al. Characterization of Performance Fatigability During a Self-paced Exercise. J Appl Physiol. 2019 Jul 18; 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 Guimarães, AU - Silva-Cavalcante,Marcos David, AU - Boari,Daniel, AU - Lima-Silva,Adriano Eduardo, AU - Millet,Guillaume Y, AU - Bertuzzi,Rômulo, Y1 - 2019/07/18/ PY - 2019/7/19/entrez PY - 2019/7/19/pubmed PY - 2019/7/19/medline KW - central fatiguer KW - electromyography KW - muscle recruitment KW - peripheral fatigue KW - power output JF - Journal of applied physiology (Bethesda, Md. : 1985) JO - J. Appl. Physiol. 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, 3600 ± 190 m) and end-spurt (ES, 4000 m) phases. Performance fatigability was characterized by using isometric maximal voluntary contractions (IMVC), while the muscle activation [i.e., voluntary activation (VA)] and contractile function of knee extensors [i.g., peak torque of potentiated twitches (TwPt)] were evaluated using electrically-evoked contractions performed (PRE) and 1 min after (POST) 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 towards the end of FS resulting in a drop on IMVC (-12%), VA (-8%) and TwPt (-23%). EMG/PO was stable during EP, with no additional drop on IMVC, VA and TwPt (-12%, -6% and -22%, respectively). EMG/PO increased abruptly during the ES, but there was no change on IMVC, VA and TwPt (-13%, -8% and -26%, respectively). These findings demonstrate that the performance fatigability during a self-paced exercise is characterized by a large drop on contractile function and muscle activation at beginning of the trial (i.e., FS), without additional change during the middle and end phases (i.e., EP and ES). SN - 1522-1601 UR - https://www.unboundmedicine.com/medline/citation/31318614/Characterization_of_performance_fatigability_during_a_self-paced_exercise L2 - http://www.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 -