Abstract
BACKGROUND/OBJECTIVES We previously demonstrated that acute exposure to hypoxia (3 h at 3000 m) increased oxidative stress markers. Thus, by using the 'living high-training low' (LHTL) method, we further hypothesized that intermittent hypoxia associated with endurance training alters the prooxidant/antioxidant balance. SUBJECTS/METHODS Twelve elite athletes from the Athletic French Federation were subjected to 18-day endurance training. They were divided into two groups: one group (control group) trained at 1200 m and lived in hypoxia (2500-3000 m simulated altitude) and the second group trained and lived at 1200 m. The subjects performed an acute hypoxic test (10 min at 4800 m) before and immediately after the training. Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA), ferric-reducing antioxidant power (FRAP), lipid-soluble antioxidants normalized for triacylglycerols, and cholesterol and retinol were measured before and after the 4800 m tests. RESULTS After the training, MDA and AOPP concentrations were decreased in response to the 4800 m test only for the control group. Eighteen days of LHTL induced a significant decrease of all antioxidant markers (FRAP, P=0.01; alpha-tocopherol, P=0.04; beta-carotene, P=0.01 and lycopene, P=0.02) for the runners. This imbalance between antioxidant and prooxidant might result from insufficient intakes in vitamins A and E. CONCLUSIONS The LHTL model characterized by the association of aerobic exercises and intermittent resting hypoxia exposures decreased the antioxidant status whereas the normoxic endurance training induced preconditioning mechanisms in response to the 4800 m test.
