Neuromuscular disturbance outlasts other symptoms of exercise-induced muscle damage

This study examined the biochemical, immunological, functional, and neuromu scular responses associated with exercise-induced muscle damage in the quad riceps of untrained men. Muscle damage and soreness was elicited with maxim al concentric/eccentric muscle actions at 0.53 rads s(-1). Significant (P<0 .05) soreness was evident 1, 2, and 3 days following muscle insult, while p lasma creatine kinase. a marker of muscle damage, was elevated 3 and 5 days post-insult. Plasma interleukin-I beta was significantly increased within 5 min, and remained elevated 1, 2, 5, and 7 days post-insult. Maximal isome tric quadriceps function was impaired (P < 0.05) for 5 days following muscl e challenge. Maximal isokinetic performance at 1.09 mds s(-1) was diminishe d (P<0.05) for 2 days post-insult: no significant decrements at 3.14 rads s (-1) were noted. Average electrical activation (iEMG) of the quadriceps was unaltered, but iEMG activity of the rectus femoris - where soreness was fo cused - was significantly increased. Neuromuscular efficiency (torque/iEMG) was compromised throughout the 10-day post-insult period investigated. Whi le other symptoms of exercise-induced muscle damage dissipate within 7 days , neuromuscular perturbation persists for at least 10 days. (C) 2000 Elsevi er Science BN. All rights reserved.