title: Work and peak torque during eccentric exercise do not predict changes in markers of muscle damage.
abstract: OBJECTIVE
  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 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.
  
  
  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, or other markers.
  
  
  CONCLUSIONS
  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.
authors.affiliation: School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Australia. dale.chapman@ausport.gov.au
authors.forename: D W
authors.initials: DW
authors.lastname: Chapman
authors.forename: M J
authors.initials: MJ
authors.lastname: Newton
authors.forename: Z
authors.initials: Z
authors.lastname: Zainuddin
authors.forename: P
authors.initials: P
authors.lastname: Sacco
authors.forename: K
authors.initials: K
authors.lastname: Nosaka
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D003402:Creatine Kinase / Q000097:blood; D004551:Elbow Joint / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000293:injuries*; D016059:Range of Motion, Articular / Q000502:physiology; D019415:Torque
chemical_list: D015415:Biomarkers; D003402:Creatine Kinase