comparative study of static stretch and hold relax on increasing the motion range of knee extension and flexibility of shortened hamstring muscles of male students in semnan

background hamstring muscles play an important role in functional activities and relaxation and most people around the world suffer from the shortened muscles. different methods of repairing were suggested and there were disagreements with regard to determination of one technique with high efficiency. objectives this study aimed to introduce more effective method, either a static stretch or hold relax technique. patients and methods in this study, 60 male students of semnan university of medical sciences (age range, 18- 25 years) who had shortened hamstring muscles were randomly categorized into three groups. one group was under test for hold relax and the other group was tested for static stretch during 4 weeks and three times a week. the third control group received no intervention. to assess these three groups, the motion range of knee extension was measured by a goniometer before and after the sessions. conclusions the results of this study suggest that both techniques (static stretch and hold relax) have a significant effect on flexibility and increasing the motion range of knee. but neither is superior regarding their effect. results results of this study showed that both methods have a significant effect on increasing the motion range of knee (p < 0.001). but no significant difference was observed between the static stretch and hold-relax techniques regarding increasing the motion range of knee (p=0.246).