title: Analyses of isokinetic and closed chain movements for hamstring reciprocal coactivation.
abstract: BACKGROUND
  Researchers have postulated that coactivation of the hamstrings during active knee extension assists the anterior cruciate ligament in maintaining knee joint stability by exerting an opposing force to anterior tibial translation.
  
  
  OBJECTIVE
  To compare the reciprocal coactivation of the hamstrings while performing low and high velocity isokinetic movements and two closed chain movements.
  
  
  METHODS
  Within subject's comparison of isokinetic and closed chain exercises.
  
  
  METHODS
  Biomechanics laboratory utilizing a Cybex norm isokinetic dynamometer and Biopac Data Collection system.
  
  
  METHODS
  12 healthy women.
  
  
  METHODS
  The root mean square of the Electromyogram (rmsEMG) was used as a measure of overall muscle activity.
  
  
  RESULTS
  The rmsEMG for hamstring coactivation during knee extension showed significant differences between the isokinetic movements and the closed chain exercises with greater coactivation when performing the isokinetic movements. In addition, greater activity was seen at the higher isokinetic velocity and during the one legged squat.
  
  
  CONCLUSIONS
  These results suggest isokinetic movements, particularly at high speed, can more effectively increase the coactivation activity of the hamstrings when compared to two closed chain activities.
authors.affiliation: Department of Kinesiology, University of New Hampshire, Durham, USA. jm@cisunix.unh.edu
authors.forename: John P
authors.initials: JP
authors.lastname: Miller
authors.forename: Ronald V
authors.initials: RV
authors.lastname: Croce
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016118:Anterior Cruciate Ligament / Q000294:innervation / Q000502:physiology; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D007700:Kinetics; D007719:Knee Joint / Q000502:physiology*; D007866:Leg / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000502:physiology; D013710:Tendons / Q000502:physiology; D016896:Treatment Outcome