This study will examine whether a technique called instrument-assisted soft tissue mobilization (IASTM) can reduce stiffness in the calf muscle (gastrocnemius) and improve ankle mobility. Muscle stiffness will be measured using a specialized ultrasound method called shear-wave elastography, while ankle range of motion will be assessed using the weight-bearing lunge test. Healthy volunteers will participate in this study, and measurements will be taken before and after a single IASTM treatment. The aim is to determine if this manual therapy technique can produce immediate changes in muscle properties and joint flexibility.

This interventional study aims to evaluate the acute effects of instrument-assisted soft tissue mobilization (IASTM) on the stiffness of the gastrocnemius muscle and ankle dorsiflexion range of motion. Muscle stiffness will be quantified using shear-wave elastography (SWE), a non-invasive ultrasound technique that measures tissue mechanical properties in real time. Ankle dorsiflexion range of motion will be assessed using the weight-bearing lunge test with the knee extended, a reliable functional measure of ankle mobility.

Participants will undergo baseline measurements followed by a standardized IASTM intervention targeting the gastrocnemius muscle. Post-treatment assessments will be conducted immediately afterward to capture acute changes. The study is designed to improve understanding of how IASTM influences muscle mechanical properties and functional joint mobility. Findings may have implications for the clinical use of IASTM in both rehabilitation and performance contexts.

Inclusion Criteria:

• Age between 18 and 45 years
• Healthy individuals without current lower limb injury
• No history of surgery to the ankle, knee, or calf
• Able to perform the weight-bearing lunge test without assistance
• Willing to refrain from intense lower-limb exercise 24 hours before testing

Exclusion Criteria:

• Current or recent (past 3 months) lower limb musculoskeletal pain or injury
• Known neuromuscular or vascular disorders affecting the lower extremity
• Use of medications affecting muscle tone or flexibility within 48 hours prior to testing
• Previous adverse reactions to manual therapy or IASTM
• Skin lesions, bruising, or conditions over the gastrocnemius that contraindicate IASTM
• Pregnancy