Work and peak torque during eccentric exercise do not predict changes in markers of muscle damage

• Published in: British journal of sports medicine Vol. 42; no. 7; p. 585
• Main Authors: Chapman, D W, Newton, M J, Zainuddin, Z, Sacco, P, Nosaka, K
• Format: Journal Article
• Language: English
• Published: England 01-07-2008
• Subjects: Adult; Biomarkers - blood; Creatine Kinase - blood; Elbow Joint - physiology; Exercise - physiology; Humans; Isometric Contraction - physiology; Male; Muscle Contraction - physiology; Muscle Fatigue - physiology; Muscle, Skeletal - injuries; Range of Motion, Articular - physiology; Torque
• ISSN: 1473-0480
• DOI: 10.1136/bjsm.2007.037929

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.
Subjects (n = 53) performed 60 maximal eccentric actions of the elbow flexors on an isokinetic dynamometer that forcibly extended the elbow joint from 60 degrees to 180 degrees at a constant velocity (90 degrees s(-1)). Markers of EIMD included maximal voluntary isometric contraction torque at 90 degrees 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.
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, or other markers.
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.