 Despite the progress of analytic techniques and the refinement of study designs, striking disagreement exists among studies regarding the influence of exercise on muscle function and redox homeostasis in the elderly. A specific exercise protocol will be applied the repeated eccentric model to produce long-lasting and extensive changes in redox biomarkers and to examine more easily the potential effects of aging. Ten young men and ten elderly men will underwent an isokinetic eccentric exercise session, which will be repeated after three weeks. Muscle function indices and redox biomarkers will be assessed in urine, plasma or erythrocytes pre exercise, immediately post exercise, 2 and 4 days post exercise. 