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KMID : 0357220140260010009
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Journal of Korean Society Physical Therapy
2014 Volume.26 No. 1 p.9 ~ p.14
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Differences of Onset Timing Between Vastus Medialis and Lateralis during Knee Isometric Contraction on Individuals with Genu Varum or Valgum
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Park Seol
Lee Woo-Jin
Park Ji-Won
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Abstract
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Purpose: The purpose of this study was to investigate how different knee alignments (genu varum and genu valgum) affected activations of quadriceps muscles with measurements of onset-time differences between vastus medialis and vastus lateralis during isometric contractions at both 30 and 60 degree knee flexion.
Methods: Fifty-two adults (20 genu varum, 12 genu valgum, and 20 control) were enrolled in this study. Subjects with over 4cm distance between knee medial epicondyles were assigned to Genu varum, while subjects with over 4cm distance between ankles medial malleolus were considered as genu valgum group. Surface EMG was used to measure onset time of both vastus medialis and vastus lateralis during isometric contraction at 30 and 60 degree knee flexion.
Results: The onset time of vastus lateralis was delayed in genu varum group, and that of vastus medialis was delayed in genu valgum group at both 30 and 60 degree knee flexions. Moreover, onset time difference at 30° knee flexion between muscles was larger in genu valgum group than genu varum group.
Conclusion: Subjects with genu varum or valgum activated quadriceps muscles with different orders pending on flexion degrees. Therefore, when quadriceps training program were planned to prevent pain or deformities, the findings that quadriceps were activated with different orders affected by knee alignments and joint degree at which trainings were performed, must be considered. If the selective training programs of quadriceps femoris are planned to prevent pain or deformities due to poor knee alignments, these should consider the subject’s knee alignment condition.
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KEYWORD
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Isometric Contraction, Quadriceps Muscle, Electromyography
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