Evaluation of exercise-induced muscle damage by surface electromyography

ObjectiveTo investigate the feasibility of a non-invasive and instant method to evaluate the degree of exercise-induced muscle damage.MethodsThirteen male college athletes (23.4 ± 1.0 year, 180.03 ± 3.51 cm, 75.93 ± 6.70 kg) took part in the trial. Measures included serum creatine kinase (CK) after eccentric and endurance exercise, and surface electromyography (sEMG) during knee extension and flexion on a Biodex unit. Relation analysis was employed between sEMG and serum CK after the eccentric and endurance exercise.ResultsThere were positive correlations between serum CK at 24 and 48 h after eccentric exercise and the AREA of sEMG for the slow isokinetic contraction before eccentric exercise (r = 0.69, P < 0.01 and 0.64, P < 0.05, respectively). The zero crossing rate (ZCR) immediately after exercise was negatively correlated with serum CK at 48 h after exercise for the slow and fast tests (r = −0.63 and −0.59, P < 0.05, respectively). Mean power frequency (MPF) and ZCR of sEMG at 6 h post endurance exercise were positively correlated with serum CK at 24 h (r = 0.73 and 0.69, P < 0.05, respectively) for the fast isokinetic test.ConclusionsExercise-induced muscle damage as evaluated by serum CK was associated with the AREA of sEMG after eccentric exercise. The ZCR of sEMG was a good predictor of muscle damage after endurance exercise.