Effectiveness of Transcutaneous Xenon Light Irradiation of Skeletal Muscle as a Pretreatment of Muscle Stretching

[Purpose] The purpose of this study was to investigate the effectiveness of transcutaneous xenon (Xe) light irradiation of skeletal muscle as a pretreatment of muscle stretching. [Subjects and Methods] Thirteen healthy volunteers participated in this study. They received two 10-minute interventions as follows: 1) Xe light irradiation of the bilateral triceps surae (TS) muscles (Xe-LITS) at prone rest, and 2) prone rest without Xe-LITS (control). Passive range of motion of ankle dorsiflexion (passive D/F ROM) and TS muscle hardness, which were measured at prone rest, were examined before and after the Xe-LITS and control treatments. [Result] Although a significant decrease in TS muscle hardness was observed after in the Xe-LITS and the control, groups, a significant increase in passive D/F ROM was observed only after Xe-LITS. [Conclusion] These results suggest that Xe light irradiation of skeletal muscle can serve as a pretreatment of muscle stretching.