The influence of photobiomodulation on the temperature of the brachial biceps during muscle fatigue protocol.

Physical activity raises body temperature. However, the literature does not contain studies about whether the employment of hotobiomodulation (PMB) could significantly influence body temperature during a muscle fatigue (MF) protocol. Thus, the aim of this study was to evaluate the effects of PMB on the temperature of the biceps brachii muscle during the performance of a muscle fatigue protocol. The study consisted of 14 volunteers who were divided into two groups (placebo group and laser group) and all individuals rotated into all groups (crossover study). To induce muscle fatigue, three maximum voluntary isometric contractions (MVIC) were performed for 50 s with a 50-s interval. During the MVIC, the muscle strength was assessed using surface electromyography and infrared temperature at 0, 5, 10, and 15 min after the tests. The laser group presented a less accentuated decrease in muscle strength, evidencing a lower rate of muscle fatigue (p > 0.05) in relation to the other groups. In the temperature analysis, the control group exhibited the highest average temperature, with a significant difference only for the placebo. The results indicate that the control displayed the greatest physical degeneration and the PMB group had a positive effect on MF attenuation and body thermoregulation.