Changes in total body and limb composition and muscle strength after a 6-8 weeks sojourn at extreme altitude (5000-8000 m)

AIM: Weight loss at extreme altitudes affects quantitative changes in fat-free mass (FFM), muscle mass and fat mass. No studies to date have focused on regional body composition and physical performance using reference methods after stays at extreme altitudes. The aim of this study was to investigate the changes in total and regional body composition, and muscle strength induced by the extreme altitudes. METHODS: Eight men aged 38.8±5.8 who took part in two different Italian expeditions on Mt. Everest (group A) and on Gasherbrum II (group B). Before and after the expedition all participants underwent anthropometric measurements, total and regional body composition assessment by DEXA, and handgrip and knee extensor strength measurements by dynamometry. RESULTS: The variations in body composition mainly involved FFM, with a similar loss in group A (-2.4±1.9 kg; P<0.05) and group B (-2.4±1.2 kg; P<0.05). Most of the FFM loss involved the limbs (-2.1±1.4 kg; P<0.01), and especially the upper limbs (-1.6±1.1 kg; P<0.01). The isotonic knee extensor strength declined in 6 of the 8 study participants, with a mean drop of -4.4±6.1 kg. CONCLUSIONS: In conclusion, our study evidence that extreme altitudes induce weight loss due mainly to a loss of fat-free mass in the limb.