| Aging blunts hyperventilation-induced hypocapnia and reduction in cerebral blood flow velocity during maximal exercise. | |
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MedLine Citation:
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PMID: 21559869 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Cerebral blood flow (CBF) increases from rest to ∼60% of peak oxygen uptake (VO(2peak)) and thereafter decreases towards baseline due to hyperventilation-induced hypocapnia and subsequent cerebral vasoconstriction. It is unknown what happens to CBF in older adults (OA), who experience a decline in CBF at rest coupled with a blunted ventilatory response during VO(2peak). In 14 OA (71 ± 10 year) and 21 young controls (YA; 23 ± 4 years), we hypothesized that OA would experience less hyperventilation-induced cerebral vasoconstriction and therefore an attenuated reduction in CBF at VO(2peak). Incremental exercise was performed on a cycle ergometer, whilst bilateral middle cerebral artery blood flow velocity (MCA V (mean); transcranial Doppler ultrasound), heart rate (HR; ECG) and end-tidal PCO(2) (P(ET)CO(2)) were monitored continuously. Blood pressure (BP) was monitored intermittently. From rest to 50% of VO(2peak), despite greater elevations in BP in OA, the change in MCA V (mean) was greater in YA compared to OA (28% vs. 15%, respectively; P < 0.0005). In the YA, at intensities >70% of VO(2peak), the hyperventilation-induced declines in both P(ET)CO(2) (14 mmHg (YA) vs. 4 mmHg (OA); P < 0.05) and MCA V (mean) (-21% (YA) vs. -7% (OA); P < 0.0005) were greater in YA compared to OA. Our findings show (1), from rest-to-mild intensity exercise (50% VO(2peak)), elevations in CBF are reduced in OA and (2) age-related declines in hyperventilation during maximal exercise result in less hypocapnic-induced cerebral vasoconstriction. |
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Authors:
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K R Marsden; M J Haykowsky; J D Smirl; H Jones; M D Nelson; Luis A Altamirano-Diaz; J C Gelinas; Y C Tzeng; K J Smith; C K Willie; D M Bailey; P N Ainslie |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-5-11 |
Journal Detail:
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Title: Age (Dordrecht, Netherlands) Volume: - ISSN: 1574-4647 ISO Abbreviation: - Publication Date: 2011 May |
Date Detail:
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Created Date: 2011-5-11 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101250497 Medline TA: Age (Dordr) Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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Department of Human Kinetics, University of British Columbia Okanagan, Kelowna, BC, Canada, V1V 2Y5. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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