This study aims to elucidate what factors take a major role to classify skilled and unskilled performers on power clean(PC) athletic motion. The subjects are twelve healthy males divided into two groups, six skilled and six unskilled with the value of “PC 100% 1RM/body weight” exceeding or not. The joint angle of the subjects' lower limbs during the PC of which intensity is set at 70% are recorded accompanied by measuring the concurrent ground reaction force. The joint torque and power are calculated from the obtained data and analyzed to evaluate a skilled performance. Our results are as follows :
1)In the skilleds' motion, the knee flexion-extension occurs with concurrently decreasing the ground reaction force, which suggests the skilled have acquired “double knee bent (DKB)” that induces so-called stretch-shortening cycle (SSC).
2)Joint angular velocity and joint torque show that skilled's muscles of lower limbs achieve a pre-contraction caused by DKB, which means the stored elastic energy is reused during the SSC. It can be explained by mechanical energy flow between neighboring joints on lower limb. The skilled shows relatively large energy flow than the unskilled.
3) Furthermore, due to transferring the energy effectively, the skilled can exert large joint torque and power. It indicates that elastic energy stored in the DKB motion accompanied by the SSC may be useful for instantaneously generating the large joint torque and joint torque power during PC.
