Effects of radial pressure wave irradiation on triceps surae muscle morphology and function.

Background: Radial pressure wave (RPW) has been introduced to sports sites as an alternative tool to massage, and there have been reports of irradiating muscles. This study aimed to clarify the effects of RPW irradiation on muscles, focusing on muscle morphology and muscle/fascial elasticity.

Methods: The participants were 23 healthy, able-bodied participants. Muscle morphology (muscle thickness, pinnate angle, muscle fascicle length), muscle and fascia elasticity (deep fascia, subfascial, muscle, deep intermuscular fascia) of the gastrocnemius medial head using ultrasound imaging equipment before and after RPW irradiation intervention. The maximum ankle dorsiflexion range of motion and isometric maximum plantarflexion muscle strength were also measured.

Results: Before and after RPW irradiation to the triceps surae muscle, muscle thickness, decreased pinnate angle, and increase in maximum ankle dorsiflexion range of motion were observed. No significant changes were observed in muscle fascicle length and maximal isometric plantarflexion strength. In addition, a significant decrease in elasticity was observed in deep fascia, subfascial, and muscle, and the change was particularly large in deep fascia and deep intermuscular fascia.

Conclusion: It was suggested that RPW irradiation to muscles might improve fascial gliding and reduce muscle elasticity. It was also found to improve joint range of motion while maintaining muscle output. Trial registration number (Japan Registry of Clinical Trials (jRCT)) Current Controlled Trials jRCT1032210104, May 21, 2021.