The purpose of the research is to measure the isokinetic strength of three parts(knee, ankle and shoulder) by each load speed from high speed to low speed utilizing the uniform velocity machine, Cybex- II system The subject of the study are current Korean national representative anthletes, Kim Ki-Hum and Lee Young-Sun. In the Knee joint of the first subject, the left extensor strength is -26.9% lower than the right extensive strength. The right flexor strength is -20.2% lower than the left extensor strength. Relative strength : The right extensor flexor strength is 117% and 52%, respectively : the left extensor and flexor strength is 85% and 65%, separately : which results in injury danger followed by his low strength and imbalance. In his ankle joint, the right PF strength is -23.4% lower than the left PF strength. The right DF strength is -7.9% lower than the left DF strength. Relative strength : the right PF and DF strength is 58% and 13%, respectively : the left PF and DF strength is 68% and 14%, separately, which results in injury danger followed by his low strength and disproportion. In his shoulder joint, the left extensor is -6.4% lower than the right extensor and the left flexor strength also is -24.8% lower than the right flexor strength. Therefore, he needs to reinforce the left extensor and flexor strength. Relative strength : The right extensor and flexor strength is 64% and 56%, respectively : the left extensor and flexor strength is 60% and 30%, separately. That is, other strength shows very excellent conditions except the left flexor strength. In the knee of the second subject, the left and right strength is that a loss is within -2.3%, which is equal and ideal. Relative strength : The right extensor and flexor strength is 123% and 56%, relatively : the left extensor and flexor strength is 119% and 58%, separately. That is, the left and right strength is relatively lower, but the strength shows very excellent conditions. In her ankle joint, the right PF strength is -3.7% lower than the right PF strength, which is more or less balanced, but the right DF strength is -20.0% lower than the left DF strength. Relative strength : The right extensor and flexor strength is 41% and 23%, respectively : the left extensor and flexor strength is 39% and 20%, separately, which results in injury danger followed by the low strength and unbalance. Therefore, to improve athletic performance and injury protection caused by strength unbalance, strength complement training should nessarily be requined.