Carboidrato no exercício: consumo alimentar e parâmetros de desempenho em corredores amadores de 5 km

Abstract

Carbohydrate (CHO) is the main nutrient responsible for energy supply to muscle contraction. For this reason, previous consumption of the nutrient contributes to the glycemic homeostasis maintenance and minimizes muscular and hepatic glycogen stores reduction. With glycogen depletion, energy production decreases which coincide with the onset of fatigue and performance decline. Despite CHO importance, there is a gap in the literature about your recommendation to improve performance in amateur athletes in long-distance running. Therefore, it is relevant to conduct studies that mimic real-life situations and evaluate the CHO intake protocols (30%, 60%, and 80%) effectiveness on the performance in amateur athletes. The purpose of this study was to analyze the effect of norm caloric diet with three CHO percentages (30%, 60%, and 80%) on physiological and biomechanical yield in 5 Km amateur runners. The sample consisted of 10 volunteers (18 to 59 years of age), male, amateur runners at Top Runners Gym in Perdões city, MG. Running test was carried out in a track race of 5000 meters at the Federal University of Lavras by up to 25 minutes. To evaluate food consumption 24-hour Recall was applied. Before and after exercise on the pre-test and 30%, 60%, and 80% CHO diets were assessed food intake, body mass, blood glucose, systolic (SBP) and diastolic blood pressure (DBP). Rating of Perceived Exertion (RPE), pacing, time, and average velocity were measured for each kilometer in the four phases of the study. To analyze the data was used Shapiro- Wilk test to verify the sample distribution and Levene test for the homogeneity of variance. Two-way ANOVA and corresponding non-parametric tests were employed to analyze running performance parameters. Pearson coefficient was used to evaluate the correlation among some variables. In all analyses, the statistical significance was p < 0.05. The results showed no significant difference among CHO diets. Besides, post-exercise glycemia increased in all dietary protocols, which means that energy demand at the end of the running was probably supplied by hepatic glucose production. The correlation between RPE and time was low in the 30% (r: 0.58) and strong in the 80% diet (r: 0.83). More CHO on diet (80%) showed a shorter time (0.66%) than the pre-test phase. Velocity increased (2.5%) and the test time reduced (2.3%) in the 80% protocol in comparison to 30%. The pre-exercise DBP in 30% (p < 0.05) and 80% diets (p < 0.05) was significantly higher compared to the pre-test phase. In post-exercise, there was a reduction in SBP and a significant increase in DBP in the 30% (p < 0.01, p = 0.01), 60% (p < 0.01, p < 0.01) and 80% diet (p < 0.01, p < 0.01), compared with the pre-test values. To conclude, changing dietary CHO suggests not improve athletic performance than the usual intake.