title: Vastus medialis oblique and vastus lateralis activity during a double-leg semisquat with or without hip adduction in patients with patellofemoral pain syndrome.
abstract: BACKGROUND
  The purpose was to investigate the effect of double-leg semisquat with hip adduction on the activation of vastus medialis oblique (VMO) and vastus lateralis (VL) in patients with patellofemoral pain syndrome (PFPS).
  
  
  METHODS
  Thirty patients with PFPS were designated to the study group, while 30 healthy matched subjects were enrolled in the control group. The activation of VL and VMO was recorded with surface electromyography (EMG) during double-leg semisquat (DS) and double-leg semisquat with hip adduction (DS-HA). The time domain and frequency domain indexes of the electromyography data were collected for analysis.
  
  
  RESULTS
  In the study group, the time domain indexes (RMS, IEMG) and frequency domain index (MPF) of VL were significant higher than VMO in the test of DS (P < 0.05); and the time domain of VMO was significantly higher in the test of DS-HA when compared to DS (P < 0.05) while there was no difference in the activation of VL.
  
  
  CONCLUSIONS
  In the study group, an increase in activity of the VMO was observed through the surface EMG signal in the double-leg semisquat exercise with hip adduction compared to the exercise without hip adduction. This finding indicates that VMO activation can be more selectively obtained through the exercise with hip adduction which can help balance the VL and VMO.
authors.affiliation: Department of Rehabilitation Medicine, the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China. mponline@163.com.|Department of Rehabilitation Medicine, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China. mponline@163.com.
authors.forename: Ping
authors.initials: P
authors.lastname: Miao
authors.affiliation: Department of Rehabilitation Medicine, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China. xuyi255@163.com.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Rehabilitation Medicine, the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China. pchrehab@163.com.
authors.forename: Cuihuan
authors.initials: C
authors.lastname: Pan
authors.affiliation: Department of Physical Therapy, University of North Texas, Health Science Center, Fort Worth, Texas, USA. Howe.liu@unthsc.edu.
authors.forename: Hao
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Rehabilitation Medicine, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China. wchrehab@163.com.
authors.forename: Chuhuai
authors.initials: C
authors.lastname: Wang
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D046788:Patellofemoral Pain Syndrome / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000503:physiopathology*; D055815:Young Adult