CORRELATION BETWEEN WORK ABSORBED, PEAK TORQUE DECREMENT AND EXERCISE-INDUCED MUSCLE DAMAGE

Abstract

Exercise-induced muscle damage (EIMD) is influenced by the intensity and type of contractions performed and results in isometric and dynamic strength loss, raised serum creatine kinase (CK), reduced range of movement (ROM) and muscle soreness (SOR). PURPOSE To determine whether changes in strength and/or work during eccentric exercise correlate with indicators of EIMD. METHODS Twenty four males (mean 31 yr) performed 60 maximal voluntary eccentric elbow flexions (90 deg/s) with isokinetic dynamometry. Exercise parameters were %change in work absorbed (WkA) and %change in peak torque (PT) over exercise. Criterion measures were: changes in concentric strength at 90 deg/s (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 taken pre- (−2 days) and 1–7 days post-exercise. Changes in criterion scores were normalised to baseline for strength measures. A Pearson (2-tailed) bivariate correlation was used to indicate interactions between predictors and outcome variables, followed by linear regressions. RESULTS WkA had a significant positive correlation with CON (r=0.557; p < 0.01) and weak positive correlation 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 was no correlation between WkA and CK or RANG; SOR did not correlate with either predictor. CONCLUSION A significant correlation existed between the change in work absorbed during an eccentric exercise bout and loss in concentric muscle strength. Varying correlations with other parameters were found (n.s.) with strength changes being better correlated than changes in muscle stiffness, swelling and soreness. Serum CK demonstrated no clear relation to either predictor