| Hyperventilation before resistance exercise: cerebral hemodynamics and orthostasis. | |
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MedLine Citation:
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PMID: 17762363 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Hyperventilation performed by athletes during preparation for resistance exercise might contribute to reports of postexercise orthostatic instability. PURPOSE: To test the hypothesis that post-resistance exercise orthostatic instability is associated with exaggerated reductions of cerebral blood-flow velocity after hyperventilation. METHODS: We recorded the ECG, end-tidal CO2, beat-by-beat finger arterial pressure, and cerebral blood-flow velocity in 10 healthy subjects. Subjects performed 10 repetitions of recumbent leg press using resistance equivalent to 80% of their six-repetition maximum during three separate trials (randomized): 1) no prior hyperventilation (NOHV); 2) after hyperventilation to an end-tidal CO2 of 3% (HV3%); and 3) after hyperventilation to an end-tidal CO2 of 2% (HV2%). After exercise, subjects stood upright for 10 s and rated symptoms of lightheadedness on a scale of 1 (none) to 5 (faint). RESULTS: Mean cerebral blood-flow velocity (CBFV(MEAN)) increased by 12% during exercise after NOHV and decreased by 14 and 25% during exercise after HV3% and HV2% (all P < 0.0001). During standing, mean arterial pressure (MAP) decreased by 96 mm Hg and CBFV(MEAN) decreased by 41 cm.s(-1) (pooled across conditions; all P < 0.0001). Absolute reductions of CBFV(MEAN) during standing were greater after HV2% compared with both NOHV and HV3% (P = 0.003). Ratings of perceived lightheadedness during standing increased with prior hyperventilation (P = 0.02) and correlated to the magnitude of reductions in MAP (r = 0.51; P = 0.003) and CBFV(MEAN) (r = 0.37; P = 0.04). CONCLUSIONS: Hyperventilation before lower-body resistance exercise exacerbates CBFV(MEAN) reductions during standing. Increased symptoms of orthostatic instability are associated with the magnitude of reductions in both MAP and CBFV(MEAN). |
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Authors:
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Steven A Romero; William H Cooke |
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Publication Detail:
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Type: Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. |
Journal Detail:
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Title: Medicine and science in sports and exercise Volume: 39 ISSN: 0195-9131 ISO Abbreviation: Med Sci Sports Exerc Publication Date: 2007 Aug |
Date Detail:
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Created Date: 2007-08-31 Completed Date: 2007-10-30 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8005433 Medline TA: Med Sci Sports Exerc Country: United States |
Other Details:
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Languages: eng Pagination: 1302-7 Citation Subset: IM; S |
Affiliation:
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Laboratory for Applied Autonomic Neurophysiology, The University of Texas at San Antonio, San Antonio, TX, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Blood Flow Velocity / physiology* Brain / blood supply* Dizziness / blood* Female Humans Hyperventilation / blood* Male Texas Weight Lifting / physiology* |
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