Effects of 830 nm Light-Emitting Diode Therapy on Delayed-Onset Muscle Soreness

Objectives. Our study investigated the effects of 830 nm light-emitting diode therapy (LEDT) for postexercise delayed-onset muscle soreness (DOMS). Methods. In this randomized control study, healthy participants were randomized into LEDT and placebo groups. LEDT (output frequency = 10 Hz; wavelength = 830 nm; total output power = 210 mW; and dose = 315 J/cm(2)) was applied to six sites in the damaged quadriceps for 10 min. The placebo group received sham LEDT with no energy output. The nondominant leg was chosen for DOMS induction, using an eccentric exercise. Visual analog scale (VAS) scores for muscle soreness, pressure pain threshold (PPT), thigh circumference, joint range of motion, and muscle strength were assessed before and immediately after exercise and at 24, 48, 72, and 96 h postexercise. Results. Forty participants were divided into the LEDT group (n = 20) and the placebo group (n = 20). Compared with the placebo group, the LEDT group exhibited significant increases in PPT values at 48, 72, and 96 h postexercise (p<0.05). The joint range of motion was significantly different between the LEDT and placebo groups at 72 and 96 h postexercise (p<0.05). No significant intergroup differences were noted in thigh circumference and muscle strength (p<0.05). Conclusion. The application of 830 nm LEDT on postexercise DOMS pain exerted an analgesic effect but did not affect the muscle repair process. Future studies should elucidate the beneficial effects of 830 nm LEDT on muscle recovery or performance.