Effects of training at simulated high altitude on exercise at sea level

Abstract

Nine healthy men trained one leg under normobaric (N) conditions (N‐leg), the other leg under hypobaric (H; 572 mmHg) conditions (H‐leg) each one 30 min, 3–4 times per week for 4 weeks at 65% of the one‐legged maximal work load that could be performed for 2 min (Wmax). They performed one‐legged exercise tests to fatigue before and after the training period under N conditions at a load corresponding to 80% of one‐legged Wmax. Muscle biopsies were taken before training from one leg and after training both from the N‐leg and the H‐leg at rest and after 15‐min exercise and analysed for high‐energy phosphates and glycogen and their degradation products. Training under N as well as under H conditions improved local energy balance in the leg (less lactate and inosine monophosphate accumulation). However, a discrepancy was found between the previously demonstrated greater increase in local oxidative potential in the H‐leg than in the N‐leg and the local energy balance during submaximal exercise, which improved less in the H‐leg than in the N‐leg (lower energy charge and higher adenosine monophosphate content). Despite less improved local energy balance after 15 min of exercise, the time to fatigue was somewhat longer in the H‐leg.