Muscle pre-activation using photobiomodulation attenuates slow component amplitude during running in heavy domain

Photobiomodulation (PBM) using light emitting diode (LED) or laser sources has been associated with physical exercise, affecting positively the uptake, transportation, and use of oxygen (O ₂ ). Therefore, the objective of the present study was to verify the effect of PBM with application of LED on the response of the fundamental and slow components of the oxygen uptake (V̇O ₂ ) kinetics during the rest-to-work running exercise transition in heavy domain. Twenty-six healthy, physically active, young men, aged between 20 and 30 years volunteered to take part in this study. Participants performed a maximal incremental running tests on a motorized treadmill to determine the gas exchange threshold and maximal oxygen uptake (V̇O _2max ) and using these data they went through two running conditions on square wave transitions in a heavy intensity domain: placebo (PLA) and LED. For each square wave test, heart rate (HR), rating of perceived exertion (RPE) and gas exchanges were monitored. PLA and LED conditions were compared using the dependent Student t-test, using the statistical significance was set at P  < 0.05. The main results showed an increase in V̇O ₂ , reduction in RPE and HR during heavy intensity constant exercise performed after the application of LED, when compared to the placebo condition. Furthermore, the analysis of V̇O ₂ kinetics also showed the reduction in the contribution of the V̇O ₂ slow component in response to the intervention with LED. In conclusion, LED induced ergogenic effect for the aerobic performance on the heavy domain.