| Human muscle net K(+) release during exercise is unaffected by elevated anaerobic metabolism, but reduced after prolonged acclimatization to 4,100 m. | |
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MedLine Citation:
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PMID: 20410475 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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It was investigated whether skeletal muscle K(+) release is linked to the degree of anaerobic energy production. Six subjects performed an incremental bicycle exercise test in normoxic and hypoxic conditions prior to and after 2 and 8 wk of acclimatization to 4,100 m. The highest workload completed by all subjects in all trials was 260 W. With acute hypoxic exposure prior to acclimatization, venous plasma [K(+)] was lower (P < 0.05) in normoxia (4.9 +/- 0.1 mM) than hypoxia (5.2 +/- 0.2 mM) at 260 W, but similar at exhaustion, which occurred at 400 +/- 9 W and 307 +/- 7 W (P < 0.05), respectively. At the same absolute exercise intensity, leg net K(+) release was unaffected by hypoxic exposure independent of acclimatization. After 8 wk of acclimatization, no difference existed in venous plasma [K(+)] between the normoxic and hypoxic trial, either at submaximal intensities or at exhaustion (360 +/- 14 W vs. 313 +/- 8 W; P < 0.05). At the same absolute exercise intensity, leg net K(+) release was less (P < 0.001) than prior to acclimatization and reached negative values in both hypoxic and normoxic conditions after acclimatization. Moreover, the reduction in plasma volume during exercise relative to rest was less (P < 0.01) in normoxic than hypoxic conditions, irrespective of the degree of acclimatization (at 260 W prior to acclimatization: -4.9 +/- 0.8% in normoxia and -10.0 +/- 0.4% in hypoxia). It is concluded that leg net K(+) release is unrelated to anaerobic energy production and that acclimatization reduces leg net K(+) release during exercise. |
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Authors:
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Nikolai B Nordsborg; José A L Calbet; Mikael Sander; Gerrit van Hall; Carsten Juel; Bengt Saltin; Carsten Lundby |
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Publication Detail:
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Type: Journal Article Date: 2010-04-21 |
Journal Detail:
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Title: American journal of physiology. Regulatory, integrative and comparative physiology Volume: 299 ISSN: 1522-1490 ISO Abbreviation: Am. J. Physiol. Regul. Integr. Comp. Physiol. Publication Date: 2010 Jul |
Date Detail:
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Created Date: 2010-06-25 Completed Date: 2010-07-08 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100901230 Medline TA: Am J Physiol Regul Integr Comp Physiol Country: United States |
Other Details:
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Languages: eng Pagination: R306-13 Citation Subset: IM |
Affiliation:
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Copenhagen Muscle Research Center, Rigshospitalet Section, Copenhagen Ø, Denmark. nnordsborg@ifi.ku.dk |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Acclimatization
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physiology* Adult Anoxia / metabolism* Blood Volume Exercise / physiology* Exercise Test Fatigue / metabolism Humans Leg Male Muscle, Skeletal / metabolism* Muscles / metabolism Plasma Volume Rest |
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