Estudo do equilíbrio hídrico de jogadores de futebol em treinamento e competição

• Autor(a) principal: Silva, Rafael Pires da
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3460
• topic: Hidratação; Futebol; Termorregulação; Desidratação; Exercício; Hydration; Soccer; Thermoregulation; Dehydration; Exercise; CNPQ::CIENCIAS DA SAUDE::EDUCACAO FISICA

The present dissertation is composed of three articles. The objective in the first article was to assess, through literature review, the fluid replacement practices used by individuals who practice physical activities and discuss how the effect of liquid temperature on gastric emptying influences this hydrating behavior. Studies on the theme have found contradicting results, probably due to the different methods used. The studies that investigate liquid temperature in the gastrointestinal tract during exercise are limited. Considering the total gastric emptying time during rest, extreme liquid temperatures have no significant effect on the total gastric emptying time, since the temperature inside the stomach normalizes quickly after ingestion of the liquid. However, there are evidences that the ingestion of ice-cold liquids increases gastric emptying in the first minutes after ingestion. This fact needs to be better investigated when it is associated with other precompetition factors, such as the psychological state of the athlete. However, low temperatures improve the palatability of the drink, implying in greater consumption by the athletes and reducing the risk of dehydration. In summary, the effects of low temperature on gastric emptying are not decisive, since fluid replacement has intervention factors that are more relevant than temperature. In the second article it was investigated the pretraining hydration status, fluid intake and sweat loss of 20 elite male Brazilian adolescent soccer players (mean ± SD age, 17.2 ± 0.5 years; height, 1.76 ± 0.05 m; body mass, 69.9 ± 6.0 kg; body mass index, 21,2 ± 3,5 kg/m2) on three consecutive days of typical training. Urine specific gravity (USG) and body mass changes were evaluated before and after training sessions to estimate hydration status. Water consumption and urine output were also recorded. Players began the days of training mildly hypohydrated (USG > 1.020) and fluid intake hardly matched fluid losses. It was warmer on day 1 (31.5 ± 2.3°C and 43.4 ± 3.2% relative humidity) and total estimated sweat losses (2822 ± 530 mL) and fluid intake (1607 ± 460 mL) were significantly xiv higher than those of days two and three. Data also indicate considerable variability in sweat losses between players and there was a significant correlation between the extent of sweat loss and the volume of fluid consumed (r2 = 0.560 p = 0.010, day 1; r2 = 0.445 p = 0.049, day 2; r2 = 0.743 p = 0.0001, day 3). We conclude that sweat losses can be substantial in young soccer players. It is suggested that enhancing athletes selfperception of sweat loss via training may avoid voluntary dehydration, whilst efforts aimed at educating players about the importance of pre-game hydration must be emphasized. And in the third article it was investigated the pre-game hydration status and fluid balance in players engaged in a Brazilian competitive soccer match played at a temperature of 28°C (relative humidity 45-55%). Intake of water and sports drink and urine output were recorded.Urine specific gravity (USG) and body mass changes were evaluated before and after the game to estimate hydration status. Data were obtained from 15 male players (age: 17 years, height: 178 cm, body mass: 69.4 kg, body mass index, 20,1 ± 2,3 kg/m2, body surface area: 1.86 m2) where 10 players performed the full-time game and 4 substitutes who did not play. Mean ± SD sweat loss of players amounted to 2.24 ± 0.63 L, and mean fluid intake was 1.12 ± 0.39 L (n = 10). Corresponding values for substitutes were 0.61 ± 0.12 L and 0.50 ± 0.10 L (n = 4). Pre-game USG was 1020 ± 0.004 and was statistically different (P < 0.05) from the post-game USG (1016 ± 0.004). The data show a large inter-individual variability in sweat losses and drinking behavior between young soccer players while under competitive match-play conditions. Fluid replacement remains a challenge for certain athletes whilst educating all players about the importance of pre-game hydration is important.