Acute Effect of Pre-stretching Foam Rolling on Hamstring Flexibility in University Students with Hamstring Muscle Shortness: A Randomized Controlled Clinical Trial

Purpose: The current study aims to compare the acute effects of pre-stretching foam rolling with static stretching alone in university students with hamstring shortness.Methods:The study included volunteers aged 18–25 years with hamstring shortness greater than 20° on the knee joint extension test. Using randomization, participants were assigned to either a static stretching-only group or pre-stretching foam rolling group. Foam rolling was performed in 2 sets of 3 minutes each, with a 20-second rest between sets. Hamstring flexibility was assessed before and 5 minutes after the interventions using the active knee extension (AKE), sit-and-reach, and Fingertips-to-Floor Distance (FFD) tests. Post-treatment between-group comparisons were performed using ANCOVA, with the baseline value included as a covariate.Results: Of the 65 individuals evaluated, 54 participants with hamstring shortness were included (n = 27 control; n = 27 foam rolling). After adjustment for baseline values, no statistically significant between-group differences were observed in right or left AKE scores (F(1, 51) = 0.73, p = 0.39, ηp² = 0.01), although the the effect size was small and favored the foam rolling group. Similarly no statistically significant between-group differences were found in the sit-and-reach test (F(1, 51) = 0.624, p = 0.343, ηp² = 0.01), although the effect size was small and favored the control group.. No statistically significant between-group difference was observed in the FFD test (F(1, 51) = 1.09, p = 0.43, ηp² = 0.01).Conclusion: Pre-stretching foam rolling did not provide an additional benefit for hamstring flexibility, as assessed by the AKE, sit-and-reach, and FFD tests. These findings indicate that, in terms of acute effects, incorporating foam rolling prior to stretching does not confer a significant advantage over static stretching alone.