Effects of Low-Volume Static Stretching and Full Range-of-Motion Resistance Training on Flexibility in Physically Active Young Adults: A Randomized Controlled Trial

Background: The purpose of the present study was to compare the effects of a low-volume static stretching protocol and low-volume full range-of-motion resistance training on flexibility in physically active young adults. Methods: A total of 48 participants (18–25 years) were included in the final analyses. Participants were randomly allocated to a static stretching group (SS, n = 16), a resistance training group (RT, n = 16), or a control group (CG, n = 16). The intervention lasted six weeks and consisted of one supervised session per week. The SS group performed two 60 s sets of high-intensity static stretching, whereas the RT group completed full range-of-motion exercise with a total duration equivalent to that of the SS group. Results: Significant improvements in flexibility (pre-to-post change) were observed in both intervention groups compared with the control group. The SS group demonstrated a statistically significant increase in range of motion compared with the control group (3.93 ± 3.45 cm, 95% CI: 2.09–5.77 vs. −0.25 ± 0.93 cm, 95% CI: −0.75–0.25, p < 0.001; Cohen’s d = 1.65), while the RT group also improved significantly compared with the control group (1.81 ± 1.75 cm, 95% CI: 0.88–2.74 vs. −0.25 ± 0.93 cm, 95% CI: −0.75–0.25; p = 0.039; Cohen’s d = 1.47). Conclusions: Both low-volume static stretching and full range-of-motion resistance training performed once weekly for six weeks effectively improved posterior chain flexibility in physically active young adults.