FORTUNA SCIENTES IUVAT Correlation Between Work Absorbed, Peak Torque Decrement and Exercise-Induced Muscle Damage D. Chapman, M. Newton, K. Nosaka, Z. Zainuddin, G. Morgan, A. Guilfoyle and P. Sacco (Sponsor: A. Morton, FACSM) School of Biomedical and Sports Science, Edith Cowan University, Western Australia Sports Science INTRODUCTION Various exercise protocols have been used to elicit exercise-induced muscle damage (EIMD) Common non invasive measures of EIMD include loss of isometric and dynamic strength, raised serum creatine kinase (CK), reduced relaxed arm angle (RANG), range of motion (ROM) and muscle soreness (SOR) EIMD is influenced by contraction type and intensity but the relationship between changes in muscle function associated with an exercise protocol and the extent of subsequent EIMD is unclear RESEARCH QUESTION Do changes in dynamic strength and or the work absorbed during eccentric exercise correlate with common indicators of EIMD? Table 1. Pearson (2-tailed) bivariate correlation matrix of the dependent variables and outcome variables Rsq = 0·2017 Rsq = 0·3103 Rsq = 0·0658 Rsq = 0·1488 Rsq = 0·0350 Table 2. Standardised coefficients for all outcome variables Rsq = 0·0765 Rsq = 0·0155 Rsq = 0·0035 Figure 3. Scatterplot graphs of Pt change, CON, ISO 90, ISO150, RANG, ROM, CK, SOR against the change in WkA METHODS Twenty four physically active males (mean 31±7yrs) participated 60 maximal voluntary eccentric contractions of the elbow flexors (90°·sec-1) using a Cybex 6000 isokinetic dynamometer were used to induce EIMD Exercise parameters measured were change in work absorbed (WkA) and change in peak torque (Pt) over exercise (expressed as a proportion of max) Criterion measures were: changes in concentric strength at 90°·sec-1 (CON), and isometric strength at 90 and 150 degrees of elbow flexion (ISO90 and ISO150 respectively), relaxed arm angle (RANG), palpated SOR, ROM and serum CK. Measurements were made pre- (-2 days) and daily for 7 days post-exercise. DATA ANALYSIS The largest change in the 7 days post-exercise for each criterion score was used for analysis (strength measures were normalised to baseline). A Pearson (2-tailed) bivariate correlation was used to indicate interactions between predictor variables (WkA and Pt) and the outcome variables (CON, ISO90, ISO150, RANG,ROM, SOR and CK), followed by linear regressions. RESULTS WkA had a significant positive correlation with CON (r=0.557; p<0.01) and weak positive correlations with ISO90 and ISO150 (r=0.257; r=0.386, n.s.). In contrast, a weak negative correlation was found between WkA and ROM (r=-0.277). Pt showed weak positive correlations with CON (r=0.486), ISO90 (r=0.340), ISO150 (r=0.355) and CK (r=0.293), but negative correlations with RANG (r=-0.232) and ROM (r=-0.339). There were no correlations between WkA and CK or RANG; SOR did not correlate with either predictor CONCLUSIONS Neither exercise variable showed a strong correlation with common indicators of muscle damage, with the exception of WkA and CON Observed changes in muscle function during eccentric exercise are not good predictors of subsequent responses in terms of the common indicators of EIMD Decreases in muscle function are likely to represent factors associated with both neuromuscular fatigue and disruption to the excitation-contraction uncoupling and contractile elements associated with eccentric contractions