title: Vastus medialis obliquus and vastus lateralis activity in open and closed kinetic chain exercises in patients with patellofemoral pain syndrome: an electromyographic study.
abstract: OBJECTIVE
  To evaluate the electromyographic activities of vastus medialis obliquus (VMO) and vastus lateralis (VL) muscles in open and closed kinetic chain exercises in subjects with patellofemoral pain syndrome (PFPS).
  
  
  METHODS
  Case-controlled study.
  
  
  METHODS
  Rehabilitation science center in a tertiary medical center.
  
  
  METHODS
  Ten patients with bilateral knee pain diagnosed with PFPS and 10 healthy volunteers.
  
  
  METHODS
  Subjects performed open kinetic chain exercise on an isokinetic dynamometer and closed kinetic chain exercise by squat-to-stand and stand-to-squat tasks. Surface electromyography was done for the VMO and VL muscles.
  
  
  METHODS
  VMO/VL ratios were calculated after normalization of muscle activities.
  
  
  RESULTS
  The VMO/VL ratios of PFPS subjects were significantly lower than were those of unimpaired subjects during knee isokinetic closed kinetic chain exercises (p = .047). However, there was no statistical difference in VMO/VL ratio between subjects with and without PFPS during closed kinetic chain exercises (p = .623). Maximum VMO/VL ratio was obtained at 60 degrees knee flexion in closed kinetic chain exercise.
  
  
  CONCLUSIONS
  In closed kinetic chain exercises, more selective VMO activation can be obtained at 60 degrees knee flexion. Maximal VMO/VL ratio was observed at this knee flexion angle, and muscle contraction intensity was also greatest.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital, Kwei-Shan, Tao-Yuan, Taiwan. fttang@adm.cgmh.org.tw
authors.forename: S F
authors.initials: SF
authors.lastname: Tang
authors.forename: C K
authors.initials: CK
authors.lastname: Chen
authors.forename: R
authors.initials: R
authors.lastname: Hsu
authors.forename: S W
authors.initials: SW
authors.lastname: Chou
authors.forename: W H
authors.initials: WH
authors.lastname: Hong
authors.forename: H L
authors.initials: HL
authors.lastname: Lew
mesh_terms: D000328:Adult; D018771:Arthralgia / Q000503:physiopathology*; D016022:Case-Control Studies; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005260:Female; D005269:Femur; D006801:Humans; D007700:Kinetics; D007719:Knee Joint; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010329:Patella; D013577:Syndrome