EFFECT OF ALTITUDE TRAINING ON RUNNER'S SKELETAL MUSCLE

Abstract

811 "Altitude training" has been linked to increases in muscle buffering capacity, oxidative enzymes and capillary density, although most studies have used either animal models, very few subjects, or high altitude. However, athletes rarely exceed elevations of 3000m during "altitude training". Therefore, we investigated the effect of 4 weeks training in low (1000-2000m) or moderate (2000-3000m) altitude on histologic and biochemical factors in the m. vastus lateralis of trained runners. Methods: Training was monitored. Base and interval pace running were characterized by velocity and VO2. VO2max, 5,000m time and O2 deficit were recorded. Three muscle biopsies were taken on each runner (12 women, 27 men, age 18-31, VO2 max 64±2 ml·kg−1·min−1, anaerobic capacity 56±4 ml·kg−1): 1) before 4 weeks sea level control training (0-200m, n=39); 2) before; and 3) after 4 weeks training at sea level (0-200m, n=13), low altitude (1250-1600m, n=13), or moderate altitude (2200-3000m, n=13, altitude groups lived at 2500m). Biopsies were analysed for fiber type and area, capillary density, activities of citrate synthase (CS), phosphofrucktokinase (PFK), 3,4 hydroxyacyl-CoA dehydrogenase (HAD), and buffer capacity. Results were analysed by ANOVA (p≤0.10). Results: There were no initial differences between groups. Training volume and relative intensity were not different between periods. Interval VO2 and velocity were lower at moderate altitude. VO2max improved in both altitude groups. 5,000m time improved only in the low altitude group. Although both fiber type areas were less during sea level training, and higher during experimental periods (in all groups), percent fiber type and capillary density did not change. There were no changes in the enzymes studied except for increased PFK activity in the sea level group during the experimental period. Tissue buffer capacity decreased in the group training at moderate altitude. Conclusions: Low altitude training is similar to sea level training. In contrast to previous work, moderate altitude training is associated with reduced tissue buffering capacity, no improvement in enzyme activities or capillary density, and may impair sea level performance.