Low-level laser therapy (LLLT) as a possible resource to attenuate muscle damage in delayed onset muscle soreness (DOMS)

The aim of this study was to investigate if the infrared laser irradiation can prevent or minimize delayed onset muscle soreness (DOMS). Eight healthy male were divided in two groups: laser group and sham laser group. All volunteers were submitted to an Eccentric Exercise Protocol (EEP) for biceps brachii to induce muscle damage. Active laser (780 nm; 50 mW; 500 mW/cm 2 ; 12 J/cm 2 ; energy of 5 J per point applied for 20 s on four points) or sham were applied two times, before and after EEP. Maximal voluntary contraction, range of motion, muscle soreness, creatine kinase activity, lactate, C-reactive problem, IL-6, IL-8, Ferric Reducing Capacity of Plasma and total bilirubin were analyzed before, 8, 24, 48, 72, 120 and 168 h after EEP. LLLT decreased IL-6 levels after 8 h of eccentric exercise in laser group. No significant differences were observed in other systemic markers of inflammation, antioxidant status or in muscle performance between groups. The results suggest a partial attenuation of muscle damage, as laser therapy was able to reduce IL-6 levels.