Redox Regulation of Satellite Cells and Skeletal Muscle Healing

A total number of 40-60 young males aged 18-30 will be initially enrolled in the study. Then, participants will be allocated to either a 1) Low glutathione (GSH-low) or a 2) High glutathione (GSH-high) group based on the basal glutathione levels of their vastus lateralis muscle. In a double-blind, crossover, repeated measures design, participants will consume either Placebo (PLA) or N-acetylcysteine (NAC) before (7-day loading phase), on exercise day and for 8 consecutive days following a single bout of intense exercise (300 eccentric contractions at 30 deg/sec in an isokinetic dynamometer). In both conditions, blood samples and muscle biopsies will be collected at baseline, before the exercise protocol and at 2- and 8-days post-exercise. Muscle performance and soreness will also be assessed at the same time points. Before each trial, participants' dietary intake will be analyzed via diet recalls. Physical activity will be analyzed only at baseline via accelerometry. A 4-week washout period will be implemented between trials. Blood samples will be analyzed for inflammation and oxidative stress markers. Muscle samples will be analyzed for satellite cell responses and myogenic potential, protein levels of intracellular signaling proteins, muscle thiols and antioxidant enzyme activity.