Efeito da suplementação aguda de tirosina sobre o desempenho e respostas termorregulatórias de corredores durante um teste contrarrelógio de 10km outdoor em ambiente quente e seco

Abstract

The purpose of the present study was to investigate whether acute Tyrosine supplementation affects thermoregulatory responses and performance of runners during a 10 km outdoor time trial in a hot and dry environment. Twelve male volunteers participated in this study, age (24.7 ± 5.5 years), height (176.8 ± 3.6 cm) and body mass (69.2 ± 5.9). Before being submited to the experimental tests, volunteers performed a rehearsal with the protocol and equipments used in the research and anthropometric evaluation. Approximately 48 hours later, they returned and underwent 02 time trial tests of 10 km, in which tyrosine (150 mg/kg ± water 250 mL + lemon pulp 50 mL) or placebo (water 250 mL ± lemon pulp) were administered. 50 ml). The situations were balanced, crossed and double-veiled. The interval between the two tests was of at least seven days. Volunteers were instructed to repeat the same meal at breakfast on the experimental days, and to consume 500 mL of water 2 hours before the start of the tests. They also performed 03 cognitive tests: 1st before supplementation, 2nd 60 minutes after tyrosine/placebo ingestion and 3rd after the time trial test. During the tests, blood and urine samples were collected, internal temperature and skin temperature, PSE and thermal sensation were recorded. It was found that runners who had increased Tyrosine intake were able to reduce total exercise time (47.37 ± 6.10 min) with advantage in comparisson to placebo recipients (48.03 ± 5.94 min); p = 0,02. Results demonstrate that the increase in the TIRO concentration altered central factors, allowing the volunteers to increase the intensity of the race in the last 2 km without this influencing the thermoregulatory, cardiovascular and perceptual variables during the exercise. No beneficial effect of tyrosine on cognitive performance was found.