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Chronic intermittent hypoxia and incremental cycling exercise independently depress muscle in vitro maximal Na+-K+-ATPase activity in well-trained athletes

Aughey, R. J., Gore, Christopher, Hahn, A. G., Garnham, Andrew, Clark, S. A., Petersen, Aaron, Roberts, A. D. and McKenna, Michael 2005, Chronic intermittent hypoxia and incremental cycling exercise independently depress muscle in vitro maximal Na+-K+-ATPase activity in well-trained athletes, Journal of applied physiology, vol. 98, no. 1, pp. 186-192.

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Title Chronic intermittent hypoxia and incremental cycling exercise independently depress muscle in vitro maximal Na+-K+-ATPase activity in well-trained athletes
Formatted title Chronic intermittent hypoxia and incremental cycling exercise independently depress muscle in vitro maximal Na+-K+-ATPase activity in well-trained athletes
Author(s) Aughey, R. J.
Gore, Christopher
Hahn, A. G.
Garnham, Andrew
Clark, S. A.
Petersen, Aaron
Roberts, A. D.
McKenna, Michael
Journal name Journal of applied physiology
Volume number 98
Issue number 1
Start page 186
End page 192
Publisher American Physiological Society
Place of publication Bethesda, Md.
Publication date 2005-01
ISSN 8750-7587
1522-1601
Keyword(s) sodium-potassium pump
potassium
muscle fatigue
altitude
Summary Athletes commonly attempt to enhance performance by training in normoxia but sleeping in hypoxia [live high and train low (LHTL)]. However, chronic hypoxia reduces muscle Na+-K+-ATPase content, whereas fatiguing contractions reduce Na+-K+-ATPase activity, which each may impair performance. We examined whether LHTL and intense exercise would decrease muscle Na+-K+-ATPase activity and whether these effects would be additive and sufficient to impair performance or plasma K+ regulation. Thirteen subjects were randomly assigned to two fitness-matched groups, LHTL (n = 6) or control (Con, n = 7). LHTL slept at simulated moderate altitude (3,000 m, inspired O2 fraction = 15.48%) for 23 nights and lived and trained by day under normoxic conditions in Canberra (altitude ~600 m). Con lived, trained, and slept in normoxia. A standardized incremental exercise test was conducted before and after LHTL. A vastus lateralis muscle biopsy was taken at rest and after exercise, before and after LHTL or Con, and analyzed for maximal Na+-K+-ATPase activity [K+-stimulated 3-O-methylfluorescein phosphatase (3-O-MFPase)] and Na+-K+-ATPase content ([3H]ouabain binding sites). 3-O-MFPase activity was decreased by –2.9 ± 2.6% in LHTL (P < 0.05) and was depressed immediately after exercise (P < 0.05) similarly in Con and LHTL (–13.0 ± 3.2 and –11.8 ± 1.5%, respectively). Plasma K+ concentration during exercise was unchanged by LHTL; [3H]ouabain binding was unchanged with LHTL or exercise. Peak oxygen consumption was reduced in LHTL (P < 0.05) but not in Con, whereas exercise work was unchanged in either group. Thus LHTL had a minor effect on, and incremental exercise reduced, Na+-K+-ATPase activity. However, the small LHTL-induced depression of 3-O-MFPase activity was insufficient to adversely affect either K+ regulation or total work performed.
Language eng
Field of Research 110602 Exercise Physiology
HERDC Research category C1 Refereed article in a scholarly journal
ERA Research output type C Journal article
Copyright notice ©2005, the American Physiological Society
Persistent URL http://hdl.handle.net/10536/DRO/DU:30008819

Document type: Journal Article
Collection: School of Exercise and Nutrition Sciences
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