Effects of Hip Internal Rotation on Knee Extensor and Hip Abductor Electromyographic Activity During Stair Up and Down

계단 오르고 내리기시 엉덩관절 내회전이 무릎관절 폄근과 엉덩관절 벌림근 근활성도에 미치는 영향

  • Oh, Jae-Seap (Dept. of Rehabilitation Therapy, The Graduate School, Yonsei University) ;
  • Kwan, Oh-Yun (Dept. of Physical Therapy, College of Health Science, Yonsei University, Dept. of Ergonomic Therapy, The Graduate School of Health and Environment, Yonsei University) ;
  • Yi, Chung-Hwi (Dept. of Physical Therapy, College of Health Science, Yonsei University, Dept. of Ergonomic Therapy, The Graduate School of Health and Environment, Yonsei University) ;
  • Jean, Hye-Sean (Dept. of Physical Therapy, College of Health Science, Yonsei University, Dept. of Ergonomic Therapy, The Graduate School of Health and Environment, Yonsei University)
  • 오재섭 (연세대학교 대학원 재활학과) ;
  • 권오윤 (연세대학교 보건과학대학 물리치료학과, 보건환경대학원 인간공학치료학과) ;
  • 이충휘 (연세대학교 보건과학대학 물리치료학과, 보건환경대학원 인간공학치료학과) ;
  • 전혜선 (연세대학교 보건과학대학 물리치료학과, 보건환경대학원 인간공학치료학과)
  • Received : 2008.02.19
  • Accepted : 2008.04.20
  • Published : 2008.05.21

Abstract

The purpose of this study was to examine the effect of the hip internal rotation on knee extensor and hip abductor electromyographic (EMG) activity during stair up and stair down mobility. Eighteen healthy subjects were recruited. All subjects performed stair up and down movements on a step of 30cm height while maintaining the hip in neutral (condition 1) and hip in internal rotation (condition 2). Surface EMG activity was recorded from five muscles (gluteus maximus, vastus lateralis (VL), vastus medialis oblique (VMO), posterior gluteus medius (Gmed), and tensor fascia latae (TFU)) and hip internal rotation angle was measured using a three dimensional motion analysis system The time period for stair up and down was normalized using the MatLab 6.5 program, and EMG activity was normalized to the value of maximal voluntary isometric contraction (%MVIC). The EMG activities according to the hip rotation (neutral or internal rotation) during the entire time period of stair up and down in each phase were compared using a paired t-test. During the entire period of stair up, the EMG activities of VL and TFL in condition 2 were significantly greater than in condition 1 (p<.05). During the entire period of stair down, the EMG activities of VL and TFL in condition 2 were significantly greater than in condition 1 (p<.05). However, the EMG activities of the other muscles were not significantly different between the conditions (p>.05). These results suggest that the stair up and down maintaining hip internal rotation was could be a contributing factor on patellar lateral tracking.