Our participants will include 40 patients within one month of stroke, 43 patients who received total hip replacement or total knee replacement two to four weeks before. The participants will be randomly assigned to isokinetic, isotonic or isometric training groups. Outcome measures including isometric peak torque of hip/knee at 90 degree of flexion, peak torque of hip/knee at angular velocity of 60 degree/s and 120 degree/s, Short Form 36 (SF-36), the Timed Up and Go test, the Oxford Hip/knee Score, the plasma concentration of hsCRP, and the level of substance P in saliva will be collected at the beginning and 4 weeks after the training program. Statistical significant differences will be determined between the improvement of outcome measures of the isokinetic and the isotonic training groups.