II. Morphological Adaptations of Human Skeletal Muscle to Chronic Hypoxia* (original) (raw)

Int J Sports Med 1990; 11: S3-S9
DOI: 10.1055/s-2007-1024846

H. Hoppeler1 , E. Kleinert1 , C. Schlegel2 , H. Claassen1 , H. Howald2 , S. R. Kayar1 , P. Cerretelli3

1Department of Anatomy, University of Berne, Berne, Switzerland
2Research Institute of the Swiss School for Physical Education and Sports, Magglingen, Switzerland
3Department of Physiology, University of Geneva, CMU, 1 rue Michel Servet, Genève, Switzerland

* This work was supported by grant 3.036.084 from Swiss National Science Foundation

Further Information

Publication History

Publication Date:
14 March 2008 (online)

Abstract

Muscle structural changes during typical mountaineering expeditions to the Himalayas were assessed by taking muscle biopsies from 14 mountaineers before and after their sojourn at high altitude (> 5000 m for over 8 weeks). M. vastus lateralis samples were analyzed morphometrically from electron micrographs. A significant reduction (-10%) of muscle cross-sectional area was found on CT scans of the thigh. Morphologically this loss in muscle mass appeared as a decrease in muscle fiber size mainly due to a loss of myofibrillar proteins. A loss of muscle oxidative capacity was also evident, as indicated by a decrease in the volume of muscle mitochondria (-25 %). In contrast, the capillary network was mostly spared from catabolism. It is therefore concluded that oxygen availability to muscle mitochondria after prolonged high-altitude exposure in humans is improved due to an unchanged capillary network, supplying a reduced muscle oxidative capacity.

Key words

high altitude - hypoxia - stereology - mitochondria - myofibrils - computed tomography - capillaries - fiber size