| Muscle energetics during prolonged cycling after exercise hypervolemia. | |
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MedLine Citation:
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PMID: 2708193 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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This study examined the question of whether increases in plasma volume (hypervolemia) induced through exercise affect muscle substrate utilization and muscle bioenergetics during prolonged heavy effort. Six untrained males (19-24 yr) were studied before and after 3 consecutive days of cycling (2 h/day at 65% of peak O2 consumption) performed in a cool environment (22-23 degrees C, 25-35% relative humidity). This protocol resulted in a 21.2% increase in plasma volume (P less than 0.05). During exercise no difference was found in the blood concentrations of glucose, lactate, and plasma free fatty acids at either 30, 60, 90, or 120 min of exercise before and after the hypervolemia. In contrast, blood alanine was higher (P less than 0.05) during both rest and exercise with hypervolemia. Measurement of muscle samples extracted by biopsy from the vastus lateralis muscle at rest and at 60 and 120 min of exercise indicated no effect of training on high-energy phosphate metabolism (ATP, ADP, creatine phosphate, creatine) or on selected glycolytic intermediate concentrations (glucose 1-phosphate, glucose 6-phosphate, fructose 6-phosphate, lactate). In contrast, training resulted in higher (P less than 0.05) muscle glucose and muscle glycogen concentrations. These changes were accompanied by blunting of the exercise-induced increase (P less than 0.05) in both blood epinephrine and norepinephrine concentrations. Plasma glucagon and serum insulin were not affected by the training. The results indicate that exercise-induced hypervolemia did not alter muscle energy homeostasis. The reduction in muscle glycogen utilization appears to be an early adaptive response to training mediated either by an increase in blood glucose utilization or a decrease in anaerobic glycolysis. |
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Authors:
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H J Green; L L Jones; M E Houston; M E Ball-Burnett; B W Farrance |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 66 ISSN: 8750-7587 ISO Abbreviation: J. Appl. Physiol. Publication Date: 1989 Feb |
Date Detail:
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Created Date: 1989-06-02 Completed Date: 1989-06-02 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 622-31 Citation Subset: IM; S |
Affiliation:
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Department of Kinesiology, University of 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 Blood Glucose / metabolism Blood Volume* Energy Metabolism Glycogen / metabolism Glycolysis Homeostasis Hormones / blood Humans Lactates / blood Lactic Acid Male Muscles / metabolism* Phosphates / metabolism Physical Exertion* |
| Chemical | |
Reg. No./Substance:
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0/Blood Glucose; 0/Hormones; 0/Lactates; 0/Phosphates; 50-21-5/Lactic Acid; 9005-79-2/Glycogen |
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