| Evidence of neuromuscular fatigue after prolonged cycling exercise. | |
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MedLine Citation:
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PMID: 11079517 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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PURPOSE: The purpose of this study was to analyze the effects of prolonged cycling exercise on metabolic, neuromuscular, and biomechanical parameters. METHODS: Eight well-trained male cyclists or triathletes performed a 2-h cycling exercise at a power output corresponding to 65% of their maximal aerobic power. Maximal concentric (CON; 60, 120, 240 degrees x s(-1)), isometric (ISO; 0 degrees s(-1)), and eccentric (ECC; -120, -60 degrees x s(-1)) contractions, electromyographic (EMG) activity of vastus lateralis (VL) and vastus medialis (VM) muscles were recorded before and after the exercise. Neural (M-wave) and contractile (isometric muscular twitch) parameters of quadriceps muscle were also analyzed using electrical stimulation techniques. RESULTS: Oxygen uptake (VO2), minute ventilation (VE), and heart rate (HR) significantly increased (P < 0.01) during the 2-h by, respectively, 9.6%, 17.7%, and 12.7%, whereas pedaling rate significantly decreased (P < 0.01) by 21% (from 87 to 69 rpm). Reductions in muscular peak torque were quite similar during CON, ISO, and ECC contractions, ranging from 11 to 15%. M-wave duration significantly increased (P < 0.05) postexercise in both VL and VM, whereas maximal amplitude and total area decreased (VM: P < 0.05, VL: NS). Significant decreases in maximal twitch tension (P < 0.01), total area of mechanical response (P < 0.01), and maximal rate of twitch tension development (P < 0.05) were found postexercise. CONCLUSIONS: A reduction in leg muscular capacity after prolonged cycling exercise resulted from both reduced neural input to the muscles and a failure of peripheral contractile mechanisms. Several hypothesis are proposed to explain a decrease in pedaling rate during the 2-h cycling with a constancy of power output and an increase in energy cost. |
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Authors:
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R Lepers; C Hausswirth; N Maffiuletti; J Brisswalter; J van Hoecke |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Medicine and science in sports and exercise Volume: 32 ISSN: 0195-9131 ISO Abbreviation: Med Sci Sports Exerc Publication Date: 2000 Nov |
Date Detail:
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Created Date: 2001-03-06 Completed Date: 2001-05-31 Revised Date: 2008-11-21 |
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: 1880-6 Citation Subset: IM; S |
Affiliation:
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Groupe Analyse du Mouvement, UFR STAPS, Université de Bourgogne, Dijon, France. romuald.lepers@u-bourgogne.fr |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Bicycling / physiology* Biomechanics Electrocardiography Electromyography Heart Rate / physiology Humans Male Muscle Contraction / physiology Muscle Fatigue / physiology* Neuromuscular Junction / physiology* Oxygen Consumption / physiology Respiratory Physiological Phenomena Time Factors |
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