Efeito da adição de proteína a uma bebida com hidratos de carbono ingerida antes do exercício em parâmetros fisiológicos e bioquímicos: Um estudo randomizado duplo-cego em atletas de meio-fundo

Abstract

The present study aimed to analyze whether the pre-exercise intake of CHO+PRO (0.75+0.25g/kg BW) vs. CHO alone (1.0g/kg BW) distinctly influences physiological parameters, blood metabolic biomarkers and performance during a stepwise running exercise comprising different intensities until exhaustion in middle distance runners. Ten athletes (7 males and 3 females - age 24.7±5.7 e 24.3±1.5 years; BW 63.6±6.8 e 54.4±3.1 kg, respectively) were tested in three occasions with 2-3 days of interval, in a randomized and double-blind design and with the inclusion of placebo. Participants arrived at the laboratory in the morning with at least 10 hours of fasting and, after resting for 15 minutes, they ingested the beverage (CHO+PRO; CHO or PLA) 30 minutes before starting the trial. This consisted in at least seven 4 min running stages with 1 min rest between each exercise period, with the increase of 1 km/h. The subsequent stage could be completed until the end or finished with exhaustion. Venous blood samples were collected in four moments (fasting, 30 minutes after the ingestion of the beverage and after the 4th and 7th stages) and capillary blood at rest and at the end of each stage. The GID and the RPE were registered after each stage. The addition of PRO had no influence in the analyzed physiological parameters (VO2máx, LAn, RER, HR), [La-], GID and RPE. Time until exhaustion was higher in PLA>CHO>CHO+PRO although not significant (1895, 1865 and 1860 seconds, respectively). The analyzed blood metabolic biomarkers (glucose, insulin, FFAs and glycine) were not different between the studied conditions. With the ingestion of PRO, non-significant decrease of glicemia and increase of insulinemia were observed when compared with ingestion of CHO only. In conclusion, the addition of PRO to a smaller amount of CHO, ingested 30 minutes before the described exercise, had no impact on the performance, physiological and biochemical indicators associated to metabolism when compared to the ingestion of CHO only.