Background and Aim: Since many of people in their functional activities mostly place their knee joint in flexed position, the hamstring muscles tend to be shortened. On the other hand, shortness of these muscles affect the knee joint directly and the ankle and hip joints indirectly. It predisposes the individual to musculo-skeletal injuries. Thus, by early diagnosing and treatment of it, the tension may be decreased, the relaxation increased and the development of injuries can be prevented. In order to achieve this goal, various stretching techniques are used. The purpose of this study is to compare the effects of static and PNF stretching on shortness of hamstring muscles in 18-30 years young women.

  Materials and Methods: Thirty 18-30 years old nonathletic women without any history of pathology in hip, knee or back were selected. They were divided into three groups with 10 women in each group(static stretch, PNF stretch and control). The two stretch groups were received stretching program five days every week for three weeks, while the control group was not.

  Results: The range of knee extension of both groups of static and PNF stretching increased (p<0/05). However there was no significant difference between these two groups (p>0/05).

  Conclusion: Employing of both methods (static and PNF stretching) increase the hamstring muscles flexibility. However there was no significant difference between two groups in increasing rang of knee extension.

  Key words: Hamstring muscles, static stretching, PNF stretching

Background and Aim: Acquaintance about different stretching methods and applying of the most effective them is necessary to improve sport skills, prevent sport injuries and accurate treatment. Several techniques of stretching exercises are recommended to improve flexibility and among them static, dynamic and PNF techniques have been widely used. The purpose of present study was to compare immediate 24 and 48 hours effects of static, dynamic and PNF stretching techniques on boy students hamstring flexibility.

Materials and Methods: The study was Quasi Experimental with one pre-test and 3 post test. One hundred and sixty eight high school students (age, 15.7 ± 0.07 years height, 171.2 ± 0.56 cm weight 63.9 ±1.14 kg) participated in this study. Participants randomly assigned into for groups.  Group one performed static, group two dynamic, group three PNF techniques of stretching and fourth group considered as a control group. The groups participated during 3 days on this study. To measure hamstring flexibility sit and reach test was administered pre and post intervention.

Results: ANOVA with repeated measures were used to analyze the data. The finding revealed significant differences between pre and post tests for all three stretching techniques immediately after stretching exercises while no changes was reported for control group (P&le0.05). Tokays fallow up tests indicated that 24 and 48 hours post intervention effects of static and PNF stretching were remained while dynamic stretching effect was disappeared 24 hours post intervention.

Conclusion:  Based on the finding of this study all three stretching techniques improved immediately hamstring flexibility while the effect of static and PNF techniques of stretching remained up to 48 hours post stretching. As a result, static and PNF stretching are more efficient than dynamic stretching.

Keywords: PNF stretching, Static stretching, Dynamic stretching, Flexibility