PNF training (C-R method) has a safe and better effect on hamstring muscle's flexibility, strength and endurance. To achieve the best combination and time in contracting and stretching process in PNF training for increment of several factors that can make simultaneously and effectively physical fitness, is controversial. The aimed of this semi-experimental study was determine of the effect of 15 seconds of maximal voluntary isometric contraction and 10 seconds of passive stretching on strength, endurance and flexibility of hamstring muscle in non-athletes men. This study performed with comparing method and designed in training and control groups with pre-test and post test. 20 non-athletes eligible male's subjects (20-25 yrs) were randomly divided in two groups. Independent variable was the implementation of six-week PNF training includes combination of 15-sec of maximal voluntary isometric contraction and 10-sec of passive stretching phases and 5 seconds rest in hamstring muscle. Dependent variables were the strength, endurance and flexibility of the hamstring muscle. Data compared with paired and independent t test (p≤0.05). Means differences of stretching, strength and endurance in comparison of pre and post test of training group and post test of two groups were significant. These results indicate that implementation of six-weeks of PNF training (C-R method) based on the overload principle with the combination of 15-sec of maximal voluntary isometric contraction and 10- sec of passive stretching, can increase flexibility, strength and endurance of hamstring muscle in non-athletes male.
