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Mechanisms of fatigue and task failure induced by sustained submaximal contractions.
Med Sci Sports Exerc. 2012 Jul; 44(7):1243-51.MS

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.

Authors+Show Affiliations

Institute of Movement Sciences and Sports Medicine, University of Geneva, Geneva, Switzerland.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

22215181

Citation

Neyroud, Daria, et al. "Mechanisms of Fatigue and Task Failure Induced By Sustained Submaximal Contractions." Medicine and Science in Sports and Exercise, vol. 44, no. 7, 2012, pp. 1243-51.
Neyroud D, Maffiuletti NA, Kayser B, et al. Mechanisms of fatigue and task failure induced by sustained submaximal contractions. Med Sci Sports Exerc. 2012;44(7):1243-51.
Neyroud, D., Maffiuletti, N. A., Kayser, B., & Place, N. (2012). Mechanisms of fatigue and task failure induced by sustained submaximal contractions. Medicine and Science in Sports and Exercise, 44(7), 1243-51. https://doi.org/10.1249/MSS.0b013e318245cc4d
Neyroud D, et al. Mechanisms of Fatigue and Task Failure Induced By Sustained Submaximal Contractions. Med Sci Sports Exerc. 2012;44(7):1243-51. PubMed PMID: 22215181.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Mechanisms of fatigue and task failure induced by sustained submaximal contractions. AU - Neyroud,Daria, AU - Maffiuletti,Nicola A, AU - Kayser,Bengt, AU - Place,Nicolas, PY - 2012/1/5/entrez PY - 2012/1/5/pubmed PY - 2012/12/10/medline SP - 1243 EP - 51 JF - Medicine and science in sports and exercise JO - Med Sci Sports Exerc VL - 44 IS - 7 N2 - 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. SN - 1530-0315 UR - https://www.unboundmedicine.com/medline/citation/22215181/Mechanisms_of_fatigue_and_task_failure_induced_by_sustained_submaximal_contractions_ L2 - https://doi.org/10.1249/MSS.0b013e318245cc4d DB - PRIME DP - Unbound Medicine ER -