Oxidative stress responses in older men during endurance training and detraining.

PURPOSE Aging is associated with increased oxidative stress, whereas systematic exercise training has been shown to improve quality of life and functional performance of the aged. This study aimed to evaluate responses of selected markers of oxidative stress and antioxidant status in inactive older men during endurance training and detraining. METHODS Nineteen older men (65-78 yr) were randomly assigned into either a control (C, N = 8) or an endurance-training (ET, N = 11, three training sessions per week, 16 wk, walking/jogging at 50-80% of HR(max)) group. Before, immediately posttraining, and after 4 months of detraining, subjects performed a progressive diagnostic treadmill test to exhaustion (GXT). Plasma samples, collected before and immediately post-GXT, were analyzed for malondialdehyde (MDA) and 3-nitrotyrosine (3-NT) levels, total antioxidant capacity (TAC), and glutathione peroxidase activity (GPX). RESULTS ET caused a 40% increase in running time and a 20% increase in maximal oxygen consumption (VO(2max)) (P < 0.05). ET lowered MDA (9% at rest, P < 0.01; and 16% postexercise, P < 0.05) and 3-NT levels (20% postexercise, P < 0.05), whereas it increased TAC (6% at rest, P < 0.01; and 14% postexercise, P < 0.05) and GPX (12% postexercise, P < 0.05). However, detraining abolished these adaptations. CONCLUSIONS ET may attenuate basal and exercise-induced lipid peroxidation and increase protection against oxidative stress by increasing TAC and GPX activity. However, training cessation may reverse these training-induced adaptations.