The objective was to examine how thiol-based antioxidant supplementation affects immune mobilization following exercise-induced skeletal muscle microtrauma. In a two-trial, double-blind, crossover, repeated measures design, 10 young men received either placebo or NAC (20 mg/kg/day) immediately after a muscle-damaging exercise protocol (300 eccentric contractions) and for eight consecutive days. Blood sampling and performance assessment were performed pre-exercise, 2h post-exercise and daily for 8 consecutive days.