The activities of flexibility on the effects of strength development

03. Summary The aim of this study was to determine the activities of flexibility on the effects of strength development. For this aim, forty boy students -the ages between 12 and 14- were choosen as the subjects of experiment. The subjects of the experiment were divided into two different groups: control group and experimental group; each group had twenty boys. The control group did not join in any physical activities during ten weeks; however, the experimental group participated into a program of the flexibility for ten weeks. The subjects in the experiment group were only included a flexibility activity which was limited with extantion of hand-wrist. For ten weeks, the flexibility activities were applied by the technique of Contract Relax which was one of PNF stretching methods. Each one of the activities was planned as three sets formating five repetitions. The experiment subjects' strength of hand-wrist extantion and paw was measured both at the beginning and at the end of the activity. The results of study indicated that there were no any differences in the level of a=0.05 among age, length, and weight of experimental and control groups (P<0.05). On the other hand, there were not statisticly meaningful differences between the results of strength measuring and flexibility of control and experiment groups in the first test (P<0.05). The most important finding of the study is that the experimental group statisticly is more flexible than control group according to the results of the last test in the flexibility development (P<0.05). On the other hand, the last test measurings of strength and flexibility of the experimental group are more positive than the last measurings of strength and flexibility of the control group. As a result, it has been reached that the flexibility activities have a positive effect on strength development, and this effect is statisticly meaningful (P<0.05). VII