VII. Maximal muscular power before and after exposure to chronic hypoxia

The maximal muscular power (both instantaneous, and average, and the cross-sectional area of the left thigh (CSA) were measured on six subjects before (B) and after (A) prolonged exposure to high altitude (above 5000 m asl). Instantaneous maximal muscular power and average maximal muscular power were determined during a standing high jump off both feet on a force platform, and CSA by computed tomography. It was observed that: (1) in B, body weight (BW) = 74.1 ± 5.8 kg, instantaneous maximal muscular power = 3330 ± 460 W (44.8 ± 3.4 W·kg-1). Average maximal muscular power = 1795 ± 395 W (24.6 ± 4.3 W·kg-1), and CSA = 184.5 ± 23.1 cm2; 2) in A, BW = 70.4 + 6.6 kg, instantaneous maximal muscular power = 3005 ± 472 W (42.5 ± 3.6 W·kg-1), (w) = 1531 ± 267 W (21.9 ± 3.1 W·kg-1), and CSA = 163.5 ± 23.1 cm2. Thus, instantaneous maximal muscular power and average maximal muscular power were decreased both in absolute terms (-9.8% and -14.7%, respectively) and per unit BW (-5.1% and -11.0%). However, because of the concomitant decrease in CSA, when expressed per unit cross-sectional area of the muscle, instantaneous maximal muscular power (9.04 ± 0.71 and 9.20 ± 0.72 W ± cm2) and average maximal muscular power (4.87 ± 0.81 and 4.70 ± 0.67 W/cm2) were unchanged. The intrinsic capacity of the muscle to generate explosive power is therefore preserved in A. It is concluded that the decrease in instantaneous maximal muscular power and average maximal muscular power after high-altitude exposure depends only on a net loss of muscle mass.