Photobiomodulation therapy with light-emitting diode does not improve lower-body muscle performance and delayed-onset muscle soreness in resistance-trained women: A randomized, controlled, crossover trial

Objectives. - Photobiomodulation (PBM) with light-emitting diode therapy (LEDT) are among the most common strategy for improving performance and recovery from physical exercise in young adults. However, its effectiveness in resistance-trained women remains contradictory. The purpose of this study was to investigate the effects of light-emitting diode therapy (LEDT) at 940 nm on lower-body muscle performance, rating of perceived exertion (RPE), and delayed-onset muscle soreness (DOMS) in resistance-trained women. Methods. - Ten young women (20.4 +/- 3.3 years) participated in a crossover study in which they received, in a counterbalanced manner, active and placebo LEDT on two occasions (T1 and T2), separated by a 7-day washout period. LEDT (130 mW output power, power density of 45 mW.cm(-2), and total energy of 48 J per leg) was applied on the quadriceps muscle immediately before the repetitions-to-failure test (6 sets at 80% of 1RM until failure) for leg press exercise. Maximum number of repetitions and RPE over the 6 sets, and DOMS at 24 and 48 hours after fatigue test were recorded. Results. - There was a significant (time P < 0.05) reduction in the maximum number of repetitions and a reciprocal increase in RPE over the 6 sets, with no statistical differences (treatment x time P > 0.05) between placebo and active LEDT conditions. DOMS increased from 24 to 48 hours after fatigue test in both conditions (time P < 0.05; treatment x time P > 0.05). Conclusion. - Our results indicate that acute LEDT at 940 nm does not improve lower-body muscle performance, RPE, and DOMS in resistance-trained women. (C) 2022 Elsevier Masson SAS. All rights reserved.