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Estimation of critical torque using intermittent isometric maximal voluntary contractions of the quadriceps in humans

Burnley, Mark (2009) Estimation of critical torque using intermittent isometric maximal voluntary contractions of the quadriceps in humans. Journal of Applied Physiology, 106 (3). pp. 975-983. ISSN 1522-1601. (doi:10.1152/japplphysiol.91474.2008) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. (Contact us about this Publication)
Official URL
http://dx.doi.org/10.1152/japplphysiol.91474.2008

Abstract

To determine whether the asymptote of the torque-duration relationship (critical torque) could be estimated from the torque measured at the end of a series of maximal voluntary contractions (MVCs) of the quadriceps, eight healthy men performed eight laboratory tests. Following familiarization, subjects performed two tests in which they were required to perform 60 isometric MVCs over a period of 5 min (3 s contraction, 2 s rest), and five tests involving intermittent isometric contractions at ?35–60% MVC, each performed to task failure. Critical torque was determined using linear regression of the torque impulse and contraction time during the submaximal tests, and the end-test torque during the MVCs was calculated from the mean of the last six contractions of the test. During the MVCs voluntary torque declined from 263.9 ± 44.6 to 77.8 ± 17.8 N·m. The end-test torque was not different from the critical torque (77.9 ± 15.9 N·m; 95% paired-sample confidence interval, ?6.5 to 6.2 N·m). The root mean squared error of the estimation of critical torque from the end-test torque was 7.1 N·m. Twitch interpolation showed that voluntary activation declined from 90.9 ± 6.5% to 66.9 ± 13.1% (P < 0.001), and the potentiated doublet response declined from 97.7 ± 23.0 to 46.9 ± 6.7 N·m (P < 0.001) during the MVCs, indicating the development of both central and peripheral fatigue. These data indicate that fatigue during 5 min of intermittent isometric MVCs of the quadriceps leads to an end-test torque that closely approximates the critical torque.

Item Type: Article
DOI/Identification number: 10.1152/japplphysiol.91474.2008
Additional information: number of additional authors: 0;
Uncontrolled keywords: power-duration relationship, central and peripheral fatigue, isokinetic dynamometry.
Subjects: H Social Sciences
Divisions: Faculties > Sciences > School of Sport and Exercise Sciences
Depositing User: Stewart Brownrigg
Date Deposited: 07 Mar 2014 00:05 UTC
Last Modified: 23 Jan 2020 04:08 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/40355 (The current URI for this page, for reference purposes)
Burnley, Mark: https://orcid.org/0000-0003-3407-561X
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