| O2 uptake and blood pressure regulation at the onset of exercise: interaction of circadian rhythm and priming exercise. | |
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MedLine Citation:
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PMID: 20889841 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Circadian rhythm has an influence on several physiological functions that contribute to athletic performance. We tested the hypothesis that circadian rhythm would affect blood pressure (BP) responses but not O(2) uptake (Vo(2)) kinetics during the transitions to moderate and heavy cycling exercises. Nine male athletes (peak Vo(2): 60.5 ± 3.2 ml·kg(-1)·min(-1)) performed multiple rides of two different cycling protocols involving sequences of 6-min bouts at moderate or heavy intensities interspersed by a 20-W baseline in the morning (7 AM) and evening (5 PM). Breath-by-breath Vo(2) and beat-by-beat BP estimated by finger cuff plethysmography were measured simultaneously throughout the protocols. Circadian rhythm did not affect Vo(2) onset kinetics determined from the phase II time constant (τ(2)) during either moderate or heavy exercise bouts with no prior priming exercise (τ(2) moderate exercise: morning 22.5 ± 4.6 s vs. evening 22.2 ± 4.6 s and τ(2) heavy exercise: morning 26.0 ± 2.7 s vs. evening 26.2 ± 2.6 s, P > 0.05). Priming exercise induced the same robust acceleration in Vo(2) kinetics during subsequent moderate and heavy exercise in the morning and evening. A novel finding was an overshoot in BP (estimated from finger cuff plethysmography) in the first minutes of each moderate and heavy exercise bout. After the initial overshoot, BP declined in association with increased skin blood flow between the third and sixth minute of the exercise bout. Priming exercise showed a greater effect in modulating the BP responses in the evening. These findings suggest that circadian rhythm interacts with priming exercise to lower BP during exercise after an initial overshoot with a greater influence in the evening associated with increased skin blood flow. |
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Authors:
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Azmy Faisal; Keith R Beavers; Richard L Hughson |
Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't Date: 2010-10-01 |
Journal Detail:
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Title: American journal of physiology. Heart and circulatory physiology Volume: 299 ISSN: 1522-1539 ISO Abbreviation: Am. J. Physiol. Heart Circ. Physiol. Publication Date: 2010 Dec |
Date Detail:
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Created Date: 2010-12-03 Completed Date: 2011-01-13 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100901228 Medline TA: Am J Physiol Heart Circ Physiol Country: United States |
Other Details:
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Languages: eng Pagination: H1832-42 Citation Subset: IM |
Affiliation:
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Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Bicycling Blood Pressure* Cardiac Output Circadian Rhythm* Exercise* Humans Hypotension / etiology, metabolism, physiopathology Kinetics Male Muscle Contraction* Muscle, Skeletal / metabolism* Oxygen / blood* Oxygen Consumption* Plethysmography Regional Blood Flow Skin / blood supply* Vascular Resistance Young Adult |
| Grant Support | |
ID/Acronym/Agency:
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//Canadian Institutes of Health Research |
| Chemical | |
Reg. No./Substance:
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7782-44-7/Oxygen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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