Phototherapy Improves Muscle Recovery and Does Not Impair Repeated Bout Effect in Plyometric Exercise.

ABSTRACT: Padoin, S, Zeffa, AC, Molina Corrêa, JC, de Angelis, TR, Moreira, TB, Barazetti, LK, and de Paula Ramos, S. Phototherapy improves muscle recovery and does not impair repeated bout effect in plyometric exercise. J Strength Cond Res 36(12): 3301-3310, 2022-The effects of photobiomodulation with red (630 nm) and near-infrared (940 nm) light wavelengths were investigated on the inhibition of exercise-induced muscle damage (EIMD) and adaptation to the repeated bout effect (RBE). Twenty-eight healthy men were randomized to receive light-emitting diode therapy (LEDT) at 630 nm (4.6 J·cm -2 , 97 J energy), LEDT at 940 nm (4.6 J·cm -2 , 114 J), or placebo. After LEDT or placebo treatment, subjects performed 100 drop-jumps (5 sets of 20 repetitions). Creatine kinase, delayed-onset muscle soreness (DOMS), countermovement jump (CMJ), and squat jump (SJ) were assessed before, immediately after, and 24, 48, and 72 hours after the bout. After 14 days, the subjects were submitted to the same plyometric exercise, without LEDT, and were evaluated again. Creatine kinase levels increased significantly 72 hours after the first bout in the placebo group in relation to the LEDT 940-nm group ( P < 0.01). The LEDT 630-nm group showed a significant increase in SJ at 24 hours ( P < 0.05), whereas, at 48 hours, the LEDT 940 nm showed a significant increase compared with the placebo group ( P < 0.05). The 2-way analysis of variance revealed an effect for treatment in the SJ ( F = 7.12; P = 0.001). No differences were found between groups for DOMS and CMJ after the first bout. After the second bout of exercise, there was no effect of treatment. The results suggest that treatment with LEDT 630 nm and LEDT 940 nm before eccentric exercise attenuates EIMD without impairing RBE.