As for the physically handicapped person due to spastic type cerebral palsy, the difference of detraining period was verified for the impact on the lower extremity muscle strength. The obtained results are as follows. 1．The knee joint muscular strength was significantly enhanced by the detraining of three months. 2．The hip joint muscular strength was not significantly enhanced by the detraining of three months. 3．The muscular strength of the knee joint and the hip joint was weakened by the detraining of six months. From these results, it is suggested that the detraining period may effect on the lower limb muscle strength. It is also suggested that the effect of detraining may depend on muscle contraction style. These findings are not necessarily corresponded to the results of the previous study that were conducted to healthy people as a subject of the research. Therefore, further study is expected
