Effects of Instrument-assisted Soft-tissue Mobilization at Three Different Application Angles on Hamstring Surface Thermal Responses

[Purpose] This study aimed to examine the thermal skin responses (thermal buildup and retention rate) to instrument-assisted soft tissue mobilization (IASTM) procedures applied on hamstrings at different angles. [Participants and Methods] Thirty university students (age: 20 ± 4 years, weight: 70.61 ± 9.11 kg, height: 168.5 ± 7.5 cm) received three sessions of 10-min Ergon IASTM treatment on their dominant limbs' hamstrings at 20°, 60°, and 90° application angles, respectively. The skin temperature was measured with a thermometer immediately before and after treatment, and every minute thereafter until it returned to the baseline value. [Results] IASTM resulted in a significant increase in skin temperature irrespective of the application angle. The thermal retention rate produced by the treatment at a 90° angle was significantly higher than that produced by the 20° application angle (78.9 vs. 64.53 min). No significant differences were observed between the 60° and 90° angle applications (72.5 vs. 78.9 min). [Conclusion] IASTM application at 60° and 90° angles can increase and retain the hamstring's skin temperature for more than an hour, creating the conditions for potential positive adaptations to local metabolism and muscle tone.