title: Effects of lumbar stabilization using a pressure biofeedback unit on muscle activity and lateral pelvic tilt during hip abduction in sidelying.
abstract: OBJECTIVE
  To assess the effects of lumbar spine stabilization using a pressure biofeedback unit on the electromyographic activity and angle of lateral pelvic tilt during hip abduction in a sidelying position.
  
  
  METHODS
  Comparative, repeated-measures study.
  
  
  METHODS
  University research laboratory.
  
  
  METHODS
  Eighteen able-bodied volunteers (9 men, 9 women) with no history of pathology.
  
  
  METHODS
  Subjects were instructed to perform hip abduction in a sidelying position in both the preferred hip abduction (PHA) and hip abduction with lumbar stabilization (HALS). A pressure biofeedback unit was used for lumbar stabilization.
  
  
  METHODS
  Surface electromyography was recorded from the quadratus lumborum, gluteus medius, internal oblique, external oblique, rectus abdominis, and multifidus muscles. Kinematic data for lateral pelvic tilt angle were measured using a motion analysis system. Dependent variables were examined with 2 (PHA vs HALS) x 2 (men vs women) analysis of variance.
  
  
  RESULTS
  Significantly decreased electromyographic activity in the quadratus lumborum (PHA, 60.39% +/- 15.62% of maximum voluntary isometric contraction [MVIC]; HALS, 27.90% +/- 13.03% of MVIC) and significantly increased electromyographic activity in the gluteus medius (PHA, 25.03% +/- 10.25% of MVIC; HALS, 46.06% +/- 21.20% of MVIC) and internal oblique (PHA, 24.25% +/- 18.10% of MVIC; HALS, 44.22% +/- 20.89% of MVIC) were found when the lumbar spine was stabilized. Lateral pelvic tilt angle (PHA, 13.86 degrees +/- 4.66 degrees; HALS, 5.55 degrees +/- 4.16 degrees) was decreased significantly when the lumbar spine was stabilized. In women the electromyographic activity (percentage of MVIC) in gluteus medius, external oblique, and rectus abdominis was significantly higher than that observed in men.
  
  
  CONCLUSIONS
  With lumbar stabilization, the gluteus medius and internal oblique activity was increased significantly, and the quadratus lumborum activity was decreased significantly, causing reduced lateral pelvic tilt in a sidelying position. These results suggest that hip abduction with lumbar stabilization is useful in excluding substitution by the quadratus lumborum.
authors.affiliation: Department of Rehabilitation Therapy, Graduate School, Yonsei University, Wonju, South Korea.
authors.forename: Heon-Seock
authors.initials: HS
authors.lastname: Cynn
authors.forename: Jae-Seop
authors.initials: JS
authors.lastname: Oh
authors.forename: Oh-Yun
authors.initials: OY
authors.lastname: Kwon
authors.forename: Chung-Hwi
authors.initials: CH
authors.lastname: Yi
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D005246:Feedback; D005260:Female; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction; D008159:Lumbar Vertebrae / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010388:Pelvis / Q000502:physiology*; D013131:Spine / Q000502:physiology*