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Int J Sports Med 1990; 11: S10-S14
DOI: 10.1055/s-2007-1024847
© Georg Thieme Verlag Stuttgart · New York

III. Effects of Chronic Hypoxia on Muscle Enzyme Activities*

H. Howald1 , D. Pette2 , J.-A. Simoneau2 , A. Uber2 , H. Hoppeler3 , P. Cerretelli4
  • 1Research Institute of the Swiss School for Physical Education and Sports, Magglingen, Switzerland
  • 2Faculty of Biology, University of Konstanz, Konstanz, Federal Republic of Germany
  • 3Department of Anatomy, University of Berne, Berne, Switzerland
  • 4Department of Physiology, University of Geneva, Genève 4, Switzerland
* This study was supported by grant 3.036.084 from the Swiss national Science Foundation. J.-A. Simoneau was a post doctoral fellow of Fonds de la Recherche en Santé du Québec, Canada
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Publication Date:
14 March 2008 (online)

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Abstract

Biopsies from the vastus lateralis muscle of seven participants in the Swiss expedition to Mt. Everest and Lhotse in 1986 were taken before departure to and after return from high altitude, and used for measurements of maximal activities of 12 reference enzymes of anaerobic and aerobic-oxidative metabolic pathways. The results indicated that strenuous exercise at high altitude induced increases in enzyme activities of glycolysis and decreases in enzyme activities of terminal substrate oxidation (the citric acid cycle, fatty acid oxidation, ketone body utilization, respiratory chain). The decreases in enzyme activities of aerobic-oxidative metabolism were related to similar decrements in mitochondrial volume density, which suggests that the enzymic changes resulted from a loss of mitochondrial structure rather than from qualitative changes of the mitochondrial population. These changes indicated that strenuous exercise may intensify the stress of high-altitude exposure and, thus, induce an aerobic to anaerobic shift of muscle energy metabolism.

Key words

aerobic-oxidative metabolism - enzyme activities - glycolysis - high altitude - hypoxia - mitochondria - skeletal muscle

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