Immediate Effects of Two IASTM Tools on Lower-Leg Tissue Stiffness and Ankle Mobility

This randomized controlled trial will investigate the immediate effects of instrument-assisted soft tissue mobilization (IASTM) performed with two different commercially available tools on posterior lower-leg tissue stiffness and ankle dorsiflexion range of motion in healthy young adults. Participants will be randomly allocated to one of three parallel groups: IASTM using a higher-cost tool, IASTM using a lower-cost tool, or passive rest without IASTM. Tissue stiffness at predefined posterior lower-leg sites and ankle dorsiflexion range of motion will be assessed before and immediately after the intervention or equivalent rest period. A single lower limb will be assessed in each participant. Participants receiving IASTM will additionally rate the pleasantness of the intervention and their perceived relaxation after the intervention. The study will determine whether IASTM produces immediate changes in tissue stiffness and ankle dorsiflexion compared with passive rest and whether these effects differ between the two IASTM tools.