Physiological Effects of Static Stretching on Muscle Force Output

Abstract

Static stretching is a common part of modern pre-exercise warm-up routines, usually as a method to reduce cramping and prevent injury. Static stretching involves the sustained stretching of a muscle, and by extension its muscle fibers and their sarcomeres, for a set period of time. This has the effect of temporarily increasing the muscle’s length. In this study, we explored the possibility that static stretching would affect muscular activity via the length-tension relationship. Thirty participants were instructed to clench a hand dynamometer while their maximum clench force, electromyography, and blood pressure (before and after the clench) were recorded. Participants first performed the maximum clench test without stretching beforehand, and then, after a waiting period of 7 minutes, they performed the clench force test again after static stretching. It was hypothesized that if static stretching was performed prior to muscle exertion, a change in the three physiological variables could be detected in reference to the participant’s baseline trial. A paired two-tailed T-Test was used to determine whether there was a statistically significant difference between the pre- and post-static stretching conditions for each of the three physiological variables tested where p<0.05 was significant. The maximum clench force data and the change in systolic blood pressure data were both found to vary significantly between pre-stretching and post-stretching trials. The electromyography data did not show a significant difference between the pre- and post-stretching conditions. Based on these results, the null hypothesis can be accepted for the electromyography data, while the null hypothesis cannot be accepted for the clench force and the change in blood pressure. This research along with future studies can be utilized to further understand the effects of static stretching on muscle activity and performance.