Effects of suboccipital or thoracolumbar self-myofascial release added to hamstring stretching on flexibility, spinal mobility, and balance in recreational athletes with hamstring tightness: a three-arm randomized controlled trial

Hamstring stretching and self-myofascial release are commonly used in sports physiotherapy, exercise preparation, and rehabilitation to acutely improve range of motion. However, whether self-myofascial release applied to anatomically remote regions provides additional benefits remains uncertain. This trial investigated whether adding suboccipital or thoracolumbar self-myofascial release to hamstring stretching improves immediate hamstring flexibility, spinal mobility, and balance compared with stretching alone in recreational athletes with hamstring tightness. In this assessor-blinded, three-arm randomized controlled trial, 103 university students who were recreational athletes and had hamstring tightness were randomly allocated to suboccipital self-myofascial release plus hamstring stretching (SO-SMFR; n = 35), thoracolumbar self-myofascial release plus hamstring stretching (TL-SMFR; n = 34), or hamstring stretching alone ( n = 34). The primary outcome was the bilateral mean Active Knee Extension Test (AKET) angle measured immediately after the intervention. Secondary outcomes included the sit-and-reach test, finger-to-floor distance, cervical and lumbar range of motion, and static and dynamic balance. Outcomes were analyzed using analysis of covariance (ANCOVA) adjusted for baseline values, followed by Holm-adjusted pairwise comparisons. Baseline-adjusted bilateral mean AKET differed among groups (F(2,99) = 4.04, p = 0.021, partial η²=0.075). TL-SMFR produced a lower adjusted AKET angle than stretching (mean difference − 3.87°, 95% CI − 6.60 to − 1.14°; Holm-adjusted p = 0.018), whereas SO-SMFR did not differ significantly from stretching (− 2.39°, 95% CI − 5.09 to 0.32°; p = 0.166). Both differences were below the prespecified 8° minimal detectable difference. No significant group effects were found for sit-and-reach, finger-to-floor, cervical mobility, or balance. A nominal lumbar-flexion effect favouring TL-SMFR did not remain significant after false-discovery-rate adjustment. TL-SMFR added to hamstring stretching produced a small immediate improvement in active knee extension compared with stretching alone; however, the magnitude of this effect was below the measurement-based MDD and did not generalize to other flexibility, spinal-mobility, or balance outcomes. The additional effect of SO-SMFR was inconclusive. Thus, the practical and clinical relevance of the observed AKET improvement remains uncertain. Repeated-session studies in sport-specific populations are needed to determine whether this effect is sustained and clinically relevant. The trial protocol was prospectively registered at ClinicalTrials.gov (NCT07096076 on March 25, 2025).