title: [Electromyogram analyses of the knee flexors and extensor for squatting jump, counter-movement jump and drop jump].
abstract: OBJECTIVE
  To observe the difference of EMG features between junior athletes and general students of knee flexor and extensor in performing various jumps.
  
  
  METHODS
  30 junior athletes and 30 middle school students took part in the test. EMG signal from knee flexor and extensor were measured, when subjects performed squatting jump, counter-movement jump and drop jump.
  
  
  RESULTS
  The results indicated that the agonists EMG activity related to sex. With the load of leg increasing, there were no significant changes in iEMG and Fmean for male. There was some increasing in iEMG but no change in Fmean for female. The antagonists EMG activity maybe related to training. With the load of leg increasing, the EMG activity of antagonists changed slightly for the junior athletes, however, increased obviously for the common students.
  
  
  CONCLUSIONS
  To improve the performance of jump, male athletes should mostly improve efficiency, however female athletes can increase the recruiting of muscle fiber. Moreover the ability of antagonists coordinating for athlete in the course of jumping is higher than that of general students.
authors.affiliation: Hebei Research Institute of Sports Science, Shijiazhuang 050011, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhou
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Wang
authors.forename: Shao-Yan
authors.initials: SY
authors.lastname: Zhang
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Liu
authors.forename: Jian
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000293:Adolescent; D056352:Athletes; D004576:Electromyography; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture / Q000502:physiology*