Bruno Manfredini Baroni

Effect of 830 nm low-level laser therapy in exercise-induced skeletal muscle fatigue in humans

This study aimed to investigate the effect of 830xa0nm low-level laser therapy (LLLT) on skeletal muscle fatigue. Ten healthy male professional volleyball players entered a crossover randomized double-blinded placebo-controlled trial. Active LLLT (830xa0nm wavelength, 100xa0mW output, spot size 0.0028xa0cm2, 200xa0s total irradiation time) or an identical placebo LLLT was delivered to four points on the biceps humeri muscle immediately before exercises. All subjects performed voluntary biceps humeri contractions with a load of 75% of the maximum voluntary contraction (MVC) force until exhaustion. After active LLLT the mean number of repetitions was significantly higher than after placebo irradiation [mean difference 4.5, standard deviation (SD) ±u20096.0, Pu2009=u20090.042], the blood lactate levels increased after exercises, but there was no significant difference between the treatments. We concluded that 830xa0nm LLLT can delay the onset of skeletal muscle fatigue in high-intensity exercises, in spite of increased blood lactate levels.

Effect of Cluster Multi-Diode Light Emitting Diode Therapy (LEDT) on Exercise-Induced Skeletal Muscle Fatigue and Skeletal Muscle Recovery in Humans

There are some indications that low‐level laser therapy (LLLT) may delay the development of skeletal muscle fatigue during high‐intensity exercise. There have also been claims that LED cluster probes may be effective for this application however there are differences between LED and laser sources like spot size, spectral width, power output, etc. In this study we wanted to test if light emitting diode therapy (LEDT) can alter muscle performance, fatigue development and biochemical markers for skeletal muscle recovery in an experimental model of biceps humeri muscle contractions.

Effect of 830 nm low-level laser therapy applied before high-intensity exercises on skeletal muscle recovery in athletes.

Our aim was to investigate the immediate effects of bilateral, 830xa0nm, low-level laser therapy (LLLT) on high-intensity exercise and biochemical markers of skeletal muscle recovery, in a randomised, double-blind, placebo-controlled, crossover trial set in a sports physiotherapy clinic. Twenty male athletes (nine professional volleyball players and eleven adolescent soccer players) participated. Active LLLT (830xa0nm wavelength, 100xa0mW, spot size 0.0028xa0cm2, 3–4 J per point) or an identical placebo LLLT was delivered to five points in the rectus femoris muscle (bilaterally). The main outcome measures were the work performed in the Wingate test: 30xa0s of maximum cycling with a load of 7.5% of body weight, and the measurement of blood lactate (BL) and creatine kinase (CK) levels before and after exercise. There was no significant difference in the work performed during the Wingate test (Pu2009>u20090.05) between subjects given active LLLT and those given placebo LLLT. For volleyball athletes, the change in CK levels from before to after the exercise test was significantly lower (Pu2009=u20090.0133) for those given active LLLT (2.52xa0Uxa0l−1 ± 7.04xa0Uxa0l−1) than for those given placebo LLLT (28.49xa0Uxa0l−1 ± 22.62xa0Uxa0l−1). For the soccer athletes, the change in blood lactate levels from before exercise to 15xa0min after exercise was significantly lower (Pu2009<u20090.01) in the group subjected to active LLLT (8.55xa0mmolxa0l−1 ± 2.14xa0mmolxa0l−1) than in the group subjected to placebo LLLT (10.52xa0mmolxa0l−1 ± 1.82xa0mmolxa0l−1). LLLT irradiation before the Wingate test seemed to inhibit an expected post-exercise increase in CK level and to accelerate post-exercise lactate removal without affecting test performance. These findings suggest that LLLT may be of benefit in accelerating post-exercise recovery.