Muscle activity and time to task failure differ with load compliance and target force for elbow flexor muscles

Thorsten Rudroff; Jamie N Justice; Matthew R Holmes; Stephen D Matthews; Roger M Enoka

doi:10.1152/japplphysiol.00605.2010

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Muscle activity and time to task failure differ with load compliance and target force for elbow flexor muscles

Journal article

Open access

Peer reviewed

Muscle activity and time to task failure differ with load compliance and target force for elbow flexor muscles

Thorsten Rudroff, Jamie N Justice, Matthew R Holmes, Stephen D Matthews and Roger M Enoka

Journal of applied physiology (1985), Vol.110(1), pp.125-136

01/2011

DOI: 10.1152/japplphysiol.00605.2010

PMCID: PMC3253001

PMID: 21030676

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Abstract

The primary purpose of this study was to determine the influence of load compliance on time to failure during sustained isometric contractions performed with the elbow flexor muscles at four submaximal target forces. Subjects pulled against a rigid restraint during the force task and maintained a constant elbow angle, while supporting an equivalent inertial load during the position task. Each task was sustained for as long as possible. Twenty-one healthy adults (23 ± 6 yr; 11 men) participated in the study. The maximal voluntary contraction (MVC) force was similar (P = 0.95) before the subjects performed the force and position tasks at each of the four target forces: 20, 30, 45, and 60% of MVC force. The time to task failure was longer for the force tasks (576 ± 80 and 325 ± 70 s) than for the position tasks (299 ± 77 and 168 ± 35 s) at target forces of 20 and 30% (P < 0.001), but was similar for the force tasks (178 ± 35 and 86 ± 14 s) and the position tasks (132 ± 29 and 87 ± 14 s) at target forces of 45 and 60% (P > 0.19). The briefer times to failure for the position task at the lower forces were accompanied by greater rates of increase in elbow flexor muscle activity, mean arterial pressure, heart rate, and rating of perceived exertion. There was no difference in the estimates of external mechanical work at any target force. The dominant mechanisms limiting time to failure of sustained isometric contractions with the elbow flexor muscles appear to change at target forces between 30 and 45% MVC, with load compliance being a significant factor at lower forces only.

Elbow Joint - physiology

Humans

Muscle Contraction - physiology

Adult

Elastic Modulus - physiology

Female

Male

Muscle, Skeletal - physiology

Physical Endurance - physiology

Task Performance and Analysis

Muscle Strength - physiology

Weight-Bearing - physiology

Details

Title: Subtitle: Muscle activity and time to task failure differ with load compliance and target force for elbow flexor muscles
Creators: Thorsten Rudroff - Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA. thorsten.rudroff@colorado.edu
Jamie N Justice
Matthew R Holmes
Stephen D Matthews
Roger M Enoka
Resource Type: Journal article
Publication Details: Journal of applied physiology (1985), Vol.110(1), pp.125-136
DOI: 10.1152/japplphysiol.00605.2010
PMID: 21030676
PMCID: PMC3253001
NLM abbreviation: J Appl Physiol (1985)
ISSN: 8750-7587
eISSN: 1522-1601
Publisher: United States
Grant note: NS043275 / NINDS NIH HHS
Language: English
Date published: 01/2011
Academic Unit: Neurology; Health, Sport, and Human Physiology
Record Identifier: 9984002465902771

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