The effect of endurance exercise at moderate altitude on serum lipid peroxidation and antioxidative functions in humans.

We investigated the effect of training and racing at moderate altitude (MA) on oxidative stress by assessment of serum diene conjugation (DC) and serum antioxidant potential (TRAP). Nine male top level skiers were studied during a national race (20-30 km) at sea level (SL). Thereafter, the athletes trained for 2 weeks at MA, after which they participated in a 20-30 km race at MA. Venous blood samples were taken before and after the race. The DC, indicating early events of lipid peroxidation, did not change during the race at SL (16 850 vs 15 900 delta Absorbance.l-1) or at MA (19 870 vs. 20 630 delta Abs.l-1). At MA serum DC was higher than at SL both before (25%) and after (30%) the race, the postrace difference being statistically significant (P < 0.05). The TRAP increased during the race at MA (from 1387 to 1943 mumol.l-1, P = 0.016), but not at SL (1713 vs 1582 mumol.l-1). These observations would suggest that the level of oxidative stress might be greater during living, training and racing at MA (higher DC levels). Increased TRAP during the race at MA may indicate that the physiological adaptation to extreme acute oxidative stress was altered. The physiological significance of this observation remains to be investigated.