Exercise therapy on skeletal muscle of muscular dystrophies has no defined parameters. The effect of low-intensity treadmill training on the oxidative stress markers and fibrosis on hindlimb muscles was investigated. Sixteen dystrophic male mdx animals were separated in trained ( mdx T/n=8) and untrained ( mdx NT/n=8) groups. Wild type animals (WT/n=8) were used as healthy control. The mdx T group runned at a horizontal treadmill (9 m/min, 30 min/day, 3 times/wk, 8 weeks). Gastrocnemius and tibial anterior muscles were collected for analysis of enzymatic/non-enzymatic oxidant activity, oxidative damage concentration, collagen fibers area morphometry. The mdx T group presented a lower collagen fiber area compared to mdx NT for gastrocnemius ( P =0.025) and tibial anterior ( P =0.000). Oxidative damage activity was higher in the mdx T group for both muscles compared to mdx NT. Catalase presented similar activity for tibial anterior ( P =0.527) or gastrocnemius ( P =0.323). Superoxide dismutase ( P =0.003) and total antioxidant capacity ( P =0.024) showed increased activity in the mdx T group at tibial anterior with no difference for gastrocnemius. Low-intensity training is considered therapeutic as it reduces collagen deposition while improving tissue redox status.