Comparative Study of Static Stretching and Instrument-Assisted Myofascial Release on Soleus Muscle Stiffness in Sedentary Females

Abstract

Background: Static Stretching (SS) and Instrument-Assisted Myofascial Release (IA-MFR) are commonly used to address restricted ankle mobility and soft-tissue limitations. However, comparative evidence regarding their effects on soleus muscle stiffness, ankle dorsiflexion, and pain in sedentary females remains limited. Objective: To compare the effects of four weeks of static stretching and IA-MFR on soleus muscle stiffness, ankle dorsiflexion range of motion, weight-bearing lunge test (WBLT) performance, and pain intensity in sedentary female university students. Methodology: This randomized controlled trial included 30 sedentary females aged 18-25 years who demonstrated soleus tightness or stiffness and restricted ankle dorsiflexion. Participants were randomly allocated equally to the SS group (n=15) or the IA-MFR group (n=15). Both interventions were administered three times weekly for four weeks under physiotherapist supervision. Pre- and post-intervention assessments included WBLT, bilateral ankle dorsiflexion range of motion, the study-specific soleus stiffness measure, and Numeric Pain Rating Scale (NPRS) scores. Within-group changes were analyzed using paired-samples t-tests and between-group differences using independent-samples t-tests. Results: Both groups demonstrated significant improvements in WBLT, bilateral ankle dorsiflexion, soleus stiffness, and pain (p<0.05). WBLT increased by 4.76 cm in the SS group and 6.00 cm in the IA-MFR group. Right and left ankle dorsiflexion increased by 4.66° and 4.54° with SS and by 6.20° and 6.07° with IA-MFR, respectively. Soleus stiffness decreased by 8.34 and 8.26 kPa with SS and by 12.26 and 12.27 kPa with IA-MFR for the right and left sides, respectively. IA-MFR showed significantly greater post-intervention improvements in mobility and stiffness, with greater pain reductions at rest, during walking, and during stretching. Conclusion: Both interventions improved ankle mobility, the study-specific soleus stiffness measure, and pain after four weeks, with larger post-intervention changes observed following IA-MFR.