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Effects of self-regulatory strength depletion on muscular performance and EMG activation

Authors


  • We thank John Moroz, Arif Jetha, and Courtney Clayton for their assistance with the study apparatus and data acquisition. This research was supported by a Standard Research Grant awarded to Kathleen A. Martin Ginis and Steven R. Bray by the Social Sciences and Humanities Research Council of Canada.

Address reprint requests to: Steven R. Bray, Ph.D., Department of Kinesiology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada.

Abstract

The purpose of the present study was to examine the effects of a self-regulatory strength depletion manipulation on performance of a physical endurance (isometric handgrip) task. In addition, the effect of depletion on EMG activity in the working forearm muscles during the endurance task was explored. Sedentary undergraduates (N=49) were randomly assigned to either a cognitive depletion condition (modified Stroop task) or a control (color word) group and completed two maximal isometric exercise endurance trials separated by the cognitive task. Participants in the depletion group showed significant (p<.05) degradations in performance and exhibited higher EMG activation on the second endurance trial (p<.05) compared to controls. Results are consistent with the limited strength model of self-regulation and are interpreted in light of the central fatigue hypothesis.

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