Estudo pré-clínico do efeito da terapia por fotobiomodulação associada ao uso de L-arginina sobre a fadiga muscular, em modelo experimental de treinamento aeróbico

Abstract

Muscle fatigue is a decline in muscle performance and its directly linked to the decreasing of muscle strength, triggering a series of biochemical reactions with the release of reactive oxygen species (ROS) and decreasing of muscle functionality. The practice of physical exercise induces structural and metabolic changes to the muscle and corroborates to its adaptation, with improvement of strength and endurance. In order to prevent deleterious effects of muscle fatigue many resources are used, such as photobiomodulation therapy (PBMT), which attenuates possible damage linked to oxidative stress, and supplementation with L-Arginine, an amino acid that is a precursor of nitric oxide (NO) which has muscle vasodilator action and can delay or prevent the occurrence of muscle fatigue. The aim of this study was to evaluate the effects of PBMT associated or not with L-Arginine supplementation on markers of oxidative stress, muscle injury and muscle fatigue in an experimental model of aerobic training. Twenty-four Wistar rats were divided into 4 groups, all of them practiced aerobic exercise on treadmill for 30 minutes daily, 5 times a week for 4 weeks and had a period of adaptation of the exercise in 2 previous weeks. The SHAM group was composed of animals that did not receive any type of supplementation or treatment, L-ARG that received L-Arginine 100 mg/kg/day before exercise, PBMT that obtained previous treatment with PBMT on the anterior tibial muscle and L-ARG associated with PBMT which received supplementation with L-Arginine 100mg/kg/day and PBMT in the tibial muscle prior to exercise. After the exercise protocol, all groups were submitted to electrically induced muscle fatigue, each animal underwent 4 tetanic contractions, then the blood and muscle were collected, the animals were euthanized after and biochemical markers CK, LDH, MDA, SOD and GPx were evaluated; maximum strength obtained (Fmax), basal contraction (BC) and force decay time in 50% of the peak in the induced tetanic contraction assays and histological analysis of the anterior tibial muscle of the animals was performed. CK and LDH levels were reduced in the PBMT group, MDA was elevated in the PBMT and L-Arginine association group, demonstrating that its association did not prevent lipid peroxidation, being lower in the PBMT, L- Arginine and SHAM groups, SOD groups PBMT and association of PBMT and L-Arginine obtained higher levels demonstrating better antioxidant action and GPx obtained higher levels in the SHAM and PBMT + L-Arginine groups than the L-Arginine group. The Fmax, BC and the decay time of the force in 50% demonstrated that the use of PBMT and L-Arginine optimized muscle strength and endurance. Histological analysis did not present hypertrophy or muscular atrophy. Conclusion: the application of PBMT and association between PBMT and L-Arginine were effective in attenuating muscle fatigue and preventing muscle injury induced by aerobic exercise.