| Summary: | 碩士 === 中國文化大學 === 運動教練研究所 === 88 === The purpose of this study was to investigate the kinematics, dynamic and neuromuscular innervation characteristics of counter movement jump(CMJ)in order to understand the effects of jump performance ,biomech parameters and EMG activities among different weight load(with no weight ,25% body weight ,50% body weight).
The subjects with the ability of squat weighting two and half of their bw were tested by athletes of Chinese Culture University(male 8) ,mean age 22.13A1.69 ,mean ht. 173.63A 3.77,mean wt. 73.35A 8.40. AMTI force platform, penny electrical goniometer and Biovision Electromyographic system were used to record the ground reaction force, knee angular displacement and the EMG-singals of Soleus, Rectus Femoris and Gastrocnemius lateral head. The result of this study show that:
1.The parameters of time and velocity:
By increasing weight load, the time of eccentric and concentric phase increase significantly; flying time(indicate sport performance), the eccentric and concentric knee angular velocity decrease significantly(p<.05).
2.The parameters of strength:
By increasing weight load, the eccentric average force, concentric average force, the maximum force, concentric impulse increase significantly. This shows that CMJ with weight load have significant change on lower extremity.
3.The parameters of power:
The maximum and average power increase by increasing weight load, then they decrease. That is: power vs. weight load curve shows the relationship of reverse U. this demonstrates that different weight load have great influence on power.
4.The parameters of power:
On the eccentric phase, the mean EMG amplitude of Soleus and Gastrocnemius lateral head don’t differ significantly except Rectus Femoris, this show that there are obvious effects on Reutus Femoris; on the concentric phase, the mean EMG amplitude of Soleus , Rectus Femoris ,Gastrocnemius lateral head don’t differ significantly.
The eccentric and concentric IEMG increase by increasing weight load because of recruiting more motor units.
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