Treinamento de corrida de endurance associado à aplicação de LED: efeitos em variáveis de desempenho, marcadores de estresse oxidativo e dor muscular em homens jovens não treinados

Abstract

With the purpose of optimizing the adaptations obtained from the running endurance training, the LED application has been used in order to accelerate the muscle recovery and as an ergogenic resource for the oxidative metabolism. However, little is known about the longitudinal effect of LED application associated with endurance training on performance parameters, oxidative stress responses and muscle soreness. Therefore, the aim of this study was to examine the effects of eight weeks of running training, prescribed by the peak velocity (Vpeak) and its respective time limit (tlim) associated with LED application on performance variables, oxidative stress markers and muscle soreness in untrained young men. Thirty young and untrained men participated in this study, who were divided into a control group (CG) and LED group (LEDG) with 15 participants each group. Both groups perfomed a training protocol during eight weeks, wherein the LEDG had the LED application and CG no. The LED was applied immediately before all training sessions in both legs, respecting the absence or presence of light emission for each group. Participants perfomed evaluations on three moments: at week 1 (W1), after the first four weeks of training (weeks 2-5) at 6th week (W6) and after the last four weeks of training (weeks 7-10) at 11th week (W11). Performance evaluations were: tests to determine Vpeak and tlim and 5-km time trial. It was collectect, in the morning, 6 ml of venous blood to analyze the oxidative stress markers: malondialdehyde (MDA) in plasma, antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) in erythrocytes, the total glutathione concentrations, reduced (GSH) and oxidized (GSSG); it was also evaluated muscle soreness through the visual analogic scale before and after all training sessions. The comparisons between groups and the moments W1, W6 and W11 was made by mixed ANOVA for repeated measures followed by Bonferroni as a post hoc test for multiple comparisons; it was calculated the percentage (%) of change and the effect sizes (ES) to express the magnitudes of changes during the trainining period. Statistical significance was set at P < 0.05. The results showed that the Vpeak increased significantly in both groups (CG: W1 = 13.4 ± 1.1, W11 = 14.4 ± 1.0 km∙h-1; LEDG: W1 = 13.4 ± 1.2, W11 = 14.6 ± 1.0 km∙h-1); the 5-km test duraiton (T5-km) decreased significantly in both groups, but this decrease was more expressive in the LEDG (W1 = 27.6 ± 3.0, W11 = 23.9 ± 2.2; -13.1 ± 5.2%) compared to CG (W1 = 27.0 ± 3.3, W11 = 24.1 ± 2.5; -10.3 ± 4.2%). After the training period the MDA concentrations remained similar in both groups (CG: W1 = 0.409 ± 0.464, W11 = 0.411 ± 0.357 nmol/MDA ml; LEDG: W1 = 0.307 ± 0.224, W11 = 0.310 ± 0.241 nmol/MDA ml) but with greater magnitude of increase in the CG compared to LEDG (274.3 ± 556.3% vs 66.7 ± 205.4%). In the LEDG it was observed an increase in the activities of enzymes CAT (W1 = 49.62 ± 25.35, W11 = 53.83 ± 29.94 U/mg Hb) and SOD (W1 = 1.06 ± 0.58, W11 = 1.33 ± 1.00 U/mg Hb), while in the CG these enzymes decreased (CAT: W1 = 63.51 ± 29.83, W11 = 45.00 ± 25.43 U/mg Hb; SOD: W1 = 1.18 ± 0.51, W11 = 1.04 ± 0.57 U/mg Hb), however, without significant differences in the comparison W1 vs W11. For GSSG there was a decrease in LEDG (W1 = 56.3 ± 83.4, W11 = 9.81 ± 4.76 μmol/g Hb) and an increase in the CG (W1 = 8.48 ± 2.94, W11 = 12.42 ± 7.90 μmol/g Hb), with significant difference between the % change values (W1 vs W11) of the groups (-13.5 ± 30.3% vs 56.3 ± 83.4%); furthermore, it was demonstrated a greater magnitude of increase in the GSH/GSSG ratio in the LEDG (W1 = 1.20 ± 0.44, W11 = 1.53 ± 0.40, 39.4 ± 55.7%, moderate ES) compared to CG (W1 = 1.26 ± 0.44, W11 = 1.36 ± 0.45; 24.9 ± 62.6%; small ES) after the training period. In the last three weeks of running training there was a tendency of lower increases in the post-session muscle soreness scores (i.e, absolute difference pre vs post-session) in the LEDG (values between 2.0 ± 2.1 and 2.1 ± 2.1 cm) compared to CG (values between 2.7 ± 2.3 and 3.1 ± 2.6 cm), with small ES in the comparison between groups for these scores. We concluded that the running endurance training associated with LED application had positive effects on improving the 5-km performance, decrease oxidative stress, increase the antioxidant defense and attenuate muscle soreness in untrained young men.