The Effect of Static Stretch and Dynamic Range of Motion Training on the Flexibility of the Hamstring Muscles

William D. Bandy, Jean M. Irion, Michelle Briggler

To date, limited information exists describing a relatively new stretching technique, dynamic range of motion (DROM). The purpose of this study was to compare the effects of DROM with static stretch on hamstring flexibility. Fifty-eight subjects, ranging in age from 21 to 41 years and with limited hamstring flexibility (defined as 30° loss of knee extension measured with the femur held at 90° of hip flexion), were randomly assigned to 1 of 3 groups. One group performed DROM 5 days a week by lying supine with the hip held in 90° of flexion. The subject then actively moved the leg into knee extension (5 seconds), held the leg in end range knee extension for 5 seconds, and then slowly lowered the leg to the initial position (5 seconds). These movements were performed 6 times per session (30 seconds of total actual stretching time). The second group performed 1 30-second static stretch, 5 days per week. The third group served as a control group and did not stretch. Before and after 6 weeks of training, flexibility of the hamstring muscles was determined in all 3 groups by measuring knee extension range of motion (ROM) with the femur maintained in 90° of hip flexion. Data were analyzed with a 2 X 3 (test X group) 2-way analysis of variance (ANOVA) with repeated measures on 1 variable (test) and appropriate post hoc analyses. The results of the 2-way ANOVA revealed a significant interaction. Further statistical post hoc analysis of data to interpret the interaction revealed significant differences between the control group (gain = 0.70°) and both stretching groups, as well as a significant difference between the static stretch group (gain = 11.42°) and the DROM group (gain = 4.26°). The results of this study suggest that, although both static stretch and DROM will increase hamstring flexibility, a 30-second static stretch was more effective than the newer technique, DROM, for enhancing flexibility. Given the fact that a 30-second static stretch increased ROM more than 2 times that of DROM, the use of DROM to increase flexibility of muscle must be questioned.

J Orthop Sports Phys Ther. 1998;27(4):295-300.

Key Words: muscle performance, exercise, flexibility, lower extremity

View Full Article