Biomechanical Characteristics and EMG Activities of Weighted Countermovement Jump

  • Feng-Jen Tsai
  • Yu Liu
  • Shau-Hua Chen
  • Yun-Ching Huang
Keywords: Biomechanics, EMG, weight training, plyometrics, counter-movement jump


The purpose of this study was to investigate the biomechanical characteristics and EMG activities during a weighted countermovement jump (WCMJ) with 0%, 25% and 50% of body weight. Eight male college students participated this study. An AMTI force platform, Penny&Giles goniometer and Biovision EMG system were used synchronously to record the related parameters while subjects performed WCMJs. The results indicate that by increasing load, the eccentric mean force, the maximum force and concentric impulse increases significantly. With the load increase, the EMG activities of soleus and gastrocnemius did not changed significantly, while the eccentric mean EMG amplitude of rectus femoris got greater. This reveals that WCMJ has a marked influence on the lower extremity, especially on the rectus femoris.