Vastus medialis obliquus and vastus lateralis activity in open and closed kinetic chain exercises in patients with patellofemoral pain syndrome: an electromyographic study

Arch Phys Med Rehabil. 2001 Oct;82(10):1441-5. doi: 10.1053/apmr.2001.26252.


Objectives: 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).

Design: Case-controlled study.

Setting: Rehabilitation science center in a tertiary medical center.

Participants: Ten patients with bilateral knee pain diagnosed with PFPS and 10 healthy volunteers.

Interventions: 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.

Main outcome measures: 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.

Conclusion: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Arthralgia / physiopathology*
  • Case-Control Studies
  • Electromyography
  • Exercise / physiology*
  • Female
  • Femur
  • Humans
  • Kinetics
  • Knee Joint*
  • Male
  • Muscle, Skeletal / physiopathology*
  • Patella
  • Syndrome