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

Bandy WB, Irion JM, Briggler M (Department of Physical Therapy, University of Central Arkansas, Conway, Ark; Department of Physical Therapy, John L McClellan Memorial Veterans Hospital, Little Rock, Ark), J Orthop Sports Phys Ther. 1998;27:295-300.

The investigators compared the effects of static stretching and a new stretching technique, dynamic range of motion (DROM), on hamstring flexibility. Fifty-eight subjects with tight hamstrings met the inclusion criteria. The term tight hamstring muscles was defined as a loss of greater than 30 degrees of knee extension when the femur was held in 90 degrees of hip flexion. A pilot study, using a test-retest design, established the reliability of measurements.

The subjects were randomly assigned to 1 of 3 groups. While standing, the first group of subjects performed 1 repetition of a 30-second passive, static stretch to the right hamstrings. Subjects in the second group performed a DROM stretch while lying supine with the right femur maintained in 90 degrees of hip flexion. The DROM stretch was active extension for the right knee (5 seconds) that was then held at end-range extension for 5 seconds and then slowly lowered into the start position (5 seconds). This movement was performed 6 times per session fin' a total actual stretching time of 30 seconds. The third group of subjects, a control group, did not stretch. Measurements of right hamstring flexibility were recorded for all subjects before and after a program of stretching sessions held 3 days a week for 6 weeks.

The means for the pretest and posttest measurements were calculated fin' each group. A 2 x 3 (test vs group) 2-way ANOVA was performed and found to be statistically significant. The test x group interaction was further analyzed by (1) dependent t testing on pretest and posttest change for each group and (2) a 1-way ANOVA on the pretest and posttest scores.

Significant differences were found in pretest and posttest means for both stretching groups but not for the control group. No differences existed in the pretest means across the 3 groups. Differences were seen in the posttest scores between the control group (gain=0.70 [degrees]) and both stretching groups and between the static stretch group (gain= 11.42 [degrees]) and the DROM group (gain=4.26 [degrees]).

The researchers concluded that, although both static stretch and DROM increased hamstring flexibility, a 30-second static stretch was more effective than DROM.

Debra Branin Coglianese, PT Beth Israel Deaconess and Children's Hospital Medical Care Center Lexingtonton, Mass