Effects of Static Stretching on Hamstring Flexibility and Sprint Times

Background/Purpose:  Research regarding the effects of flexibility training and stretching on athletic performance has produced conflicting results. A common method researchers have used to better understand the effects of static stretching is sprint performance. Even though studies have shown static stretching to have negative effects on sprint performance, many coaches, trainers, and therapists still recommend static stretching for their athletes. The purpose of this study was to compare the flexibility of the hamstring muscle (H), and its effect on sprinting times (ST) in recreational athletes. It was hypothesized that a static H stretch prior to sprinting would increase H flexibility and decrease ST.

Method:  Thirteen males (age = 20.85 ± 1.57 yrs.; ht. = 180.89 ± 6.14 cm; wt. = 78.99 ± 10.96 kg) and eleven females (age = 20.55 ± 0.69 yrs.; ht. = 170.14 cm; wt. = 63.14 ± 8.73 kg) from a private university participated in a two-day experiment. The first day participants performed a controlled dynamic warm- up of repeated exercises over the width of a basketball court. A Saunders Digital Inclinometer measured H flexibility prior to the Brower Timing measured 200 meter sprint. Day two, the same dynamic warm-up was completed followed by a 30-second static H stretch performed with the ankle dorsiflexed and heel placed on a waist-high surface. Again, H flexibility was measured prior to the 200 meter sprint. Four paired t-tests were run at the 0.05 level using Minitab 16.

Analysis/Results:  The two-paired t-test resulted in statistical significance for male pre-stretch H flexibility vs. post-stretch H flexibility (86.92 ± 14.01 vs. 97.98 ± 10.32, p = 0.001) and female pre-stretch H flexibility vs. post-stretch H flexibility (101.18 ± 15.09 vs. 106.64 ± 13.28, p = 0.039). There was no statistical significance for the male pre-stretch ST vs. post- stretch ST (28.045 ± 2.126 vs. 28.235 ± 2.376, p = 0.702) and female pre-stretch ST vs. post-stretch ST (36.85 ± 4.5 vs. 36.08 ± 4.04, p = 0.103).

Conclusions: Statistical analysis indicated a significant increase in H flexibility when a static stretch was implemented prior to a 200 meter sprint for both males and females. No statistically significant decrease in 200 meter ST occurred in both males and females. This research is of value to coaches, trainers and therapists in their recommendations to athletes regarding performance. Emphasis does not need to be placed on static H stretches when attempting to decrease ST.