Context: Skeletal muscle fatigue and exercise performance are novel areas of research and clinical application in the photobiomodulation field, and positive outcomes have been reported in several studies; however, the optimal measures have not been fully established.Objective: To assess the acute effect of photobiomodulation therapy (PBMT) combining superpulsed lasers (low-level laser therapy) and light-emitting diodes (LEDs) on muscle performance during a progressive cardiopulmonary treadmill exercise test.Design: Crossover study. Setting: Laboratory. Patients or Other Participants: Twenty untrained male volunteers (age ¼ 26.0 6 6.0 years, height ¼ 175.0 6 10.0 cm, mass ¼ 74.8 6 10.9 kg).Intervention(s): Participants received PBMT with either combined superpulsed lasers and LED (active PBMT) or placebo at session 1 and the other treatment at session 2. All participants completed a cardiopulmonary test on a treadmill after each treatment. For active PBMT, we performed the irradiation at 17 sites on each lower limb (9 on the quadriceps, 6 on the hamstrings, and 2 on the gastrocnemius muscles), using a cluster with 12 diodes (four 905-nm superpulsed laser diodes with an average power of 0.3125 mW, peak power of 12.5 W for each diode, and frequency of 250 Hz; four 875-nm infrared LED diodes with an average power of 17.5 mW; and four 640-nm red LED diodes with an average power of 15 mW) and delivering a dose of 30 J per site.Main Outcome Measure(s): Distance covered, time until exhaustion, pulmonary ventilation, and dyspnea score.Results: The distance covered (1.96 6 0.30 versus 1.84 6 0.40 km, t 19 ¼ 2.119, P , .001) and time until exhaustion on the cardiopulmonary test (780.2 6 91.0 versus 742.1 6 94.0 seconds, t 19 ¼ 3.028, P , .001) was greater after active PBMT than after placebo. Pulmonary ventilation was greater (76.4 6 21.9 versus 74.3 6 19.8 L/min, t 19 ¼ 0.180, P ¼ .004) and the score for dyspnea was lower (3.0 [interquartile range ¼ 0.5-9.0] versus 4.0 [0.0-9.0], U ¼ 184.000, P , .001) after active PBMT than after placebo.Conclusions: The combination of lasers and LEDs increased the time, distance, and pulmonary ventilation and decreased the score of dyspnea during a cardiopulmonary test. Key Words: low-level laser therapy, light-emitting diode therapy, fatigue, progressive-intensity exercise
Key PointsPhotobiomodulation therapy combines the use of superpulsed lasers and light-emitting diodes. When applied before a progressive cardiopulmonary exercise test on a treadmill, photobiomodulation therapy increased distance covered, time to exhaustion, and pulmonary ventilation and decreased dyspnea sensation in healthy volunteers.
