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Int J Sports Med 1990; 11: S3-S9
DOI: 10.1055/s-2007-1024846
© Georg Thieme Verlag Stuttgart · New York

II. Morphological Adaptations of Human Skeletal Muscle to Chronic Hypoxia*

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
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Publication History

Publication Date:
14 March 2008 (online)

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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

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