Effects of statically performed toe touch stretches on torque production of the hamstring and quadriceps muscle groups

Abstract

Stretching used as part of a warm up routine for later performance has become not only popular but also recommended by physical educators. Warm up stretches are thought to enhance performance and reduce the incidence of soft tissue injuries occurring in the subsequent performance. However almost no evidence exists as to the effect of these stretches upon the torque production of these muscles in a later performance. It was the purpose of this study to investigate the effects of warm up stretches upon torque production. Between the pre- and post-test conditions on the treatment day, subjects (n=24) performed three 30s static toe touches interspersed with equal rest intervals. On the control day subjects spent the equivalent period of time in a relatively inactive state. They were allowed to stand and walk, but instructed to refrain from stretching. On two consecutive days at approximately the same time, subjects were tested for maximum torque production at four movement speeds (0, 60, 150, & 240 σ/s) using a Cybex II isokinetic exercise device. Five minutes of no load cycling preceded each pre-test. Each test consisted of four maximum knee extension/flexion cycles. All torque and position recordings were made at a chart paper speed of 25mm/s. Peak torque and the amount of time required to attain peak torque were digitized from the chart recordings using a Neumonics digitizer. Torque at 45° were also obtained from the strips. For each subject 0° was determined at full extension prior to the pre-test. Means values obtained from the two middle cycles for all variables were used for analysis. Hamstring/quadriceps ratios (H/Q) were computed for peak torques and torques at 45°. Peak torques for both the hamstring and quadriceps muscles were found to reduce as the speed of movement increased, but H/Q values were unaffected by speed. None were effected by stretch. Torques measured at 45° and their ratio were also unaffected by stretch, but the ratios were speed dependent. No evidence was found to suggest that stretch when used as part of a warm up routine provided any facilitory or inhibitory affect upon torque production in a subsequent performance.