Efeitos da aplicação do laser de baixa intensidade (830nm) no desempenho muscular antes e após protocolo de fadiga induzida pelo exercício em atletas de futebol

Abstract

Recent studies have investigated whether low-level laser therapy (LLLT) can optimize muscle performance during exercise. A randomized, double-blind, placebocontrolled study that investigate the effect of LLLT before and after exercise on quadriceps muscle performance and evaluate the changes in serum lactate and creatine kinase (CK) levels. A sample of 27 healthy volunteers (male soccer players) were divided into 3 groups: placebo, pre-fatigue laser, and post-fatigue laser. Subjects performed 2 sessions of stretching followed by blood collection (for measurement of lactate and CK) at baseline and after fatigue of the quadriceps by leg extension. We measured the time to fatigue and the number and maximum load (ML) of repetitions tolerated. Serum lactate levels were measured before and 5, 10, and 15 minutes after exercise and CK levels before and 5 minutes after exercise. The number of repetitions (p = 0.8965), ML (p = 0.9915), and duration of fatigue (p = 0.8424) were similar among the groups. Post-fatigue laser treatment significantly decreased the serum lactate concentration relative to placebo treatment (p < 0.01) and also within the group over time (after 5 min vs. after 10 and 15 minutes, p < 0.05 both). The CK level was lower in the post-fatigue laser group (p < 0.01). Laser application either before or after fatigue reduced the post-fatigue concentrations of serum lactate and CK, improving the performance of the quadriceps. The results were more pronounced in the post-fatigue laser group.