摘要：This study evaluated the immediate effects of photobiomodulation (PBM) on neuromuscular performance of the elbow flexor muscles. This is a randomized, clinical trial. Eighty volunteers of both genders (age, 23.3 ± 2.7 yrs; height, 1.68 ± 0.08 cm; weight, 67.8 ± 14.3 kg; BMI, 23.6 ± 3.6 kg•m ~(-2) ) participated in this study. The subjects were randomly allocated into 4 groups: G1 control group; G2 placebo; G3 laser applied before fatigue protocol; and G4 laser immediately after fatigue protocol. The subjects were submitted to an evaluation of the isokinetic performance and electromyographic activity of the elbow flexor muscles. A laser device (808 nm) was used for applying PBM with a power of 100 mW and total energy of 20 J. Muscular fatigue protocol consisted of 30 maximal concentric isokinetic contractions at 120°•sec~(-1) of the elbow flexor muscles. A reduction in the peak torque normalized by body weight (P<0.001) and average power (P=0.03) was only observed for the control group, between the initial and final evaluations. A significant difference was also observed between the control group and the other groups in relation to the same variables (P<0.001 and P=0.02), but with no difference between the groups that had laser applied or the placebo. There was no difference in electromyographic variables. PBM showed similar results to the placebo group, suggesting that this resource does not modify the isokinetic performance after induced muscle fatigue.
