| Association Between Knee Extensor Strength and EMG Activities During Squat Movement. | |
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MedLine Citation:
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PMID: 21552158 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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PURPOSE:: The present study aimed to clarify how the force-generating capability of quadriceps femoris (QF) is associated to its surface EMG activity during a body mass-based squat movement. METHODS:: Isometric knee extension torque (KET) during maximal voluntary contraction (MVC) and EMG activities of the rectus femoris and vastus lateralis muscles during a body mass-based squat movement were determined in 53 men and 48 women aged 19 to 90 years, including 18 frail elderly persons who used the long-term care insurance system. The rectified EMG signals during the squat movement were averaged and normalized as the relative value (%EMGmax) to that during MVC. The %EMGmax values for RF and VL were averaged and used as an index representing the level of muscular activities of QF during the squat movement (QF %EMGmax). RESULTS:: QF %EMGmax was nonlinearly related to KET relative to body mass (KET/BM). Linear piecewise continuous regression analysis showed that there was a breakpoint of 1.9 N·m/kg in the relationship between the two variables. In individuals with KET/BM less than 1.9 N·m/kg, QF %EMGmax rapidly increased as KET/BM decreased. CONCLUSIONS:: The current results indicate that the activity level of QF during a body mass-based squat movement is influenced by its force generation capability. For individuals with a KET/BM less than 1.9 N·m/kg, body mass-based squat movement is considered to be a fairly high-intensity exercise. The breakpoint of 1.9 N·m/kg may be assumed to be a threshold level of knee extensor strength, which should be maintained for performing the activities of daily living without great difficulty. |
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Authors:
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Eiji Fujita; Hiroaki Kanehisa; Yasuhide Yoshitake; Tetsuo Fukunaga; Hidetsugu Nishizono |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-5-4 |
Journal Detail:
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Title: Medicine and science in sports and exercise Volume: - ISSN: 1530-0315 ISO Abbreviation: - Publication Date: 2011 May |
Date Detail:
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Created Date: 2011-5-9 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8005433 Medline TA: Med Sci Sports Exerc Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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