IRCT201207194203N5 IRCT 2012-08-16 Deputy of Research, Semnan University of Medical Sciences Hamstring muscle stretching and Whole body vibration Comparative study of the effect of whole body vibration and subjects' position on hamstring flexibility in subjects with hamstring shortness. 2012-07-22 anticipated 72 Complete https://irct.ir/trial/4430 interventional Randomization: Randomized, Blinding: Single blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment. N/A Muscle contracture. Intervention 1: Control (1): Stretching of both hamstrings simultaneously, without WBV. Stretch will be perform in 5 sets of 30 seconds with 20 s rest interval. Stretches will be done 3 times per week for 4 weeks. Intervention 2: Intervention (1): Stretching of both hamstrings simultaneously, on WBV platform when it is on. Stretch will be perform in 5 sets of 30 seconds with 20 s rest interval. The parameters of WBV are as follows: High amplitude and frequency of 30 Htz. Stretches will be done 3 times per week for 4 weeks. Intervention 3: Intervention (2): Stretching of hamstrings individually on WBV platform when it is on. Stretch will be perform in 5 sets of 30 seconds with 20 s rest interval, separately. The parameters of WBV are as follows: High amplitude and frequency of 30 Htz. Stretches will be done 3 times per week for 4 weeks. Intervention 4: Intervention (3): The subject firstly will receive WBV for 5 sets of 30 seconds with 20 s rest interval in squat position. After receiving WBV, stretch will be perform for both hamstrings simultaneously, for 5 sets of 30 seconds with 20 s rest interval. Stretches will be done 3 times per week for 4 weeks. Intervention 5: Intervention (4): The subject firstly will receive WBV for 5 sets of 30 seconds with 20 s rest interval in squat position. After receiving WBV, stretch will be perform for individual hamstrings separately, for 5 sets of 30 seconds with 20 s rest interval. Stretches will be done 3 times per week for 4 weeks. Intervention 6: Control (2): Stretching of hamstrings individually without WBV. Stretch will be perform in 5 sets of 30 seconds with 20 s rest interval, separately Stretches will be done 3 times per week for 4 weeks.