Morphological adaptations of human skeletal muscle to chronic hypoxia

Int J Sports Med. 1990 Feb;11 Suppl 1:S3-9. doi: 10.1055/s-2007-1024846.


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 (greater than 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acclimatization* / physiology
  • Adult
  • Altitude*
  • Body Composition
  • Capillaries / anatomy & histology
  • Chronic Disease
  • Humans
  • Hypoxia / pathology*
  • Hypoxia / physiopathology
  • Male
  • Mountaineering
  • Muscles / blood supply
  • Muscles / physiopathology
  • Muscles / ultrastructure*