Work And Peak Torque During Eccentric Exercise Do Not Predict Changes In Markers Of Muscle Damage

Dale W Chapman ^1*, Michael J Newton ¹, Zanial Zainuddin ², Paul Sacco ³ and Kazunori Nosaka ¹

¹ School of Exercise, Biomedical and Health Sciences. Edith Cowan University, Australia
² Department of Sports Science, University Technology of Malaysia, Malaysia
³ School of Health and Bioscience, University of East London, United Kingdom

^* To whom correspondence should be addressed. E-mail: d.chapman{at}ecu.edu.au.

Accepted 28 August 2007

Abstract

Objectives: Large inter-subject variability in responses to eccentric exercise has been reported. This study investigated the hypothesis that the variability of changes in indirect markers of exercise-induced muscle damage (EIMD) would be explained by work performed and/or torque generated during eccentric exercise. Methods: Subjects (n=53) performed 60 maximal eccentric actions of the elbow flexors on an isokinetic dynamometer that forcibly extended the elbow joint from 60° to 180° at a constant velocity (90°·s^-1). Markers of EIMD included maximal voluntary isometric contraction torque at 90° elbow flexion (MVC), range of motion, plasma creatine kinase activity and muscle soreness. Measurements were taken 2 days before, immediately after, and 1-4 days post-exercise. Pearson’s correlation coefficient was used to examine relationships between exercise parameters (total work, change in total work, torque produced during exercise, change in peak torque) and markers of EIMD. Results: Large inter-subject variability was evident for both work and torque during exercise, and changes in all markers of EIMD. Contrary to the hypothesis, total work (normalised for individual pre-exercise MVC) did not correlate significantly with any markers of EIMD, with the exception of MVC (r = 0.3). Total work performed and changes in total work showed higher correlations with some markers, but no r-values exceeded 0.4. Normalised exercise torque and the changes in peak torque during exercise were not correlated with changes in MVC, nor other markers. Conclusion: These results suggest the large inter-subject variability in responses to eccentric exercise is not associated with work performed or torque generated during eccentric exercise.

Key Words: delayed-onset muscle soreness (DOMS), elbow flexors, isometric strength, plasma creatine kinase activity

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