Effects of instrument assisted and functional soft tissue mobilization on hamstring flexibility and skinfold thickness in sedentary adults

Hamstring muscle tightness is common among sedentary individuals and can adversely affect muscle performance and overall function. This randomized controlled study aimed to compare the effects of static stretching, Instrument-Assisted Soft Tissue Mobilization (IASTM), and functional IASTM techniques on hamstring muscle tightness and skinfold thickness in sedentary adults. This randomized controlled study enrolled 51 sedentary adults aged 18 to 45 years into one of three intervention groups: IASTM (group 1), functional IASTM (group 2), and static stretching (control). Each intervention was administered three times weekly for four weeks. Knee extension was measured at 90 degrees hip flexion to assess hamstring tightness, and skinfold thickness was evaluated at baseline (T₀), immediately after the intervention (T₁), and at two (T₂) and four (T₃) weeks postintervention. All three interventions led to significant improvements in hamstring flexibility, with no statistically significant differences among the groups (p > 0.05). Notably, both group 1 and group 2 presented significantly greater reductions in skinfold thickness than did the control group (p < 0.05). These results highlight the importance of incorporating IASTM-based methods into rehabilitation and prevention strategies for sedentary individuals with tight hamstrings. Practitioners may consider focusing on IASTM or functional IASTM to decrease soft tissue thickness, although static stretching continues to be effective for enhancing flexibility. A combined approach involving both stretching and soft tissue mobilization could provide the best overall benefits for musculoskeletal health in the inactive group.