SPORT STRETCHING - EFFECT ON PASSIVE MUSCLE-STIFFNESS OF SHORT HAMSTRINGS

Objective: To evaluate the effects of one 10-minute stretch on muscle stiffness in subjects with short hamstrings. Design: Randomized contro l trial. Setting: Laboratory for human movement sciences in the depart ment of rehabilitation of a university hospital. Subjects: Sixteen stu dents from the Department of Human Movement Sciences participated with informed consent in the experiment. Subjects were limited to men and women without a history of neurological and orthopedic disorders. To s elect subjects with short hamstrings, the finger-ground distance had t o be greater than Ocm (unable to touch the floor when bending forward) and the manual leg lifting was not to exceed 80 degrees. One group of 10 subjects performed static stretching exercises during 10 minutes i nterspersed with relaxing, whereas the untreated group of 6 subjects w as used as a control. Main Outcome Measures: The instrumental straight -leg-raising set-up enables the measurement of the force needed to lif t the leg, range of motion (ROM), pelvic-femoral angle, and the electr omyogram of the hamstrings. These variables provide information about the stiffness, elongation, and state of activity of the hamstring musc les. Results: One 10-minute sport: stretch resulted in a significant i ncrease in passive muscle moment, ROM, and elongation of the hamstring s. There was no significant change in the course of the passive muscle stiffness curve with respect to the prestretch stiffness curve. Concl usions: One session of static stretching does not influence the course of the passive muscle stiffness curve. The increased ROM, ie, the ext ensibility of the hamstrings, results from an increase in the stretch tolerance. (C) 1996 by the American Congress of Rehabilitation Medicin e and the American Academy of Physical Medicine and Rehabilitation