The purpose of this investigation was to determine which stretching technique, static or ballistic, is most effective for increasing hamstring muscle length when delivered at the same stretching dose over a 4-week training program. A single-blind, randomized controlled trial design was used in this investigation. Thirty-two participants (16 women and 16 men) between the ages of 18 and 27 years participated in the study. All participants who had a pre-training knee extension angle of less than 20 degrees were excluded from the study. Subjects were randomly assigned to one of 3 groups: ballistic stretching, static stretching, or control group. Participants in the experimental stretching groups (ballistic and static stretching) performed one 30-second stretch 3 times per week for a period of 4 weeks. Statistical analysis consisted of a 2-way analysis of variance (group x sex) with an a priori alpha level of 0.05. No interaction between group and sex was identified (p = 0.4217). The main effect of sex was not statistically significant (p = 0.2099). The main effect for group was statistically significant at p < 0.0001.
Post hoc analysis revealed that both static and ballistic stretching group produced greater increases in hamstring length than the control group. The static stretching group demonstrated a statistically greater increase in hamstring muscle length than the ballistic stretching group. No injuries or complications were attributed to either stretching program.