Estudo do equilíbrio hídrico de jogadores de futebol em treinamento e competição
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2010-06-18
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Universidade Federal de Viçosa
Resumo
Esta dissertação é composta de três artigos. No primeiro artigo o objetivo foi analisar, através de revisão de literatura, os procedimentos de reposição de líquidos adotados por praticantes de atividade física e discutir como o efeito da temperatura do líquido sobre o esvaziamento gástrico influencia esse comportamento de hidratação. Em condições de exercício, são insuficientes os trabalhos que avaliam a temperatura do líquido ingerido no trato gastrintestinal. Durante o repouso, observa-se que os efeitos de temperaturas extremas, considerando o tempo total de esvaziamento gástrico, não são significantes, uma vez que a temperatura intragástrica após a ingestão da bebida normaliza-se rapidamente. Contudo, existem evidências de que o consumo de bebidas geladas aumenta o esvaziamento gástrico nos primeiros minutos após a ingestão. Este fato deve ser melhor estudado, quando associado a outros fatores pré-competição, como o estado psicológico do atleta. Entretanto, baixas temperaturas melhoram a
palatabilidade da solução, implicando em maior ação de hidratação pelos atletas, diminuindo o risco de desidratação. Conclui-se que os efeitos da baixa temperatura sobre o esvaziamento gástrico não são determinantes, tendo a reposição de líquidos fatores de intervenção mais relevantes do que a temperatura. No segundo artigo investigou-se o estado de hidratação prétreino, o consumo de líquidos e a perda de suor de 20 atletas de futebol masculino em três dias consecutivos de treinamento. (Média ± desvio padrão: idade, 17,2 ± 0,5 anos; estatura, 1,76 ± 0,05 m; massa corporal, 69,9 ± 6,0 kg; índice de massa corporal, 21,2 ± 3,5 kg/m2). A gravidade específica da urina (GEU) e a variação da massa corporal foram aferidas
antes e após os treinos para estimar o estado de hidratação dos atletas. Também foram avaliados o volume de água ingerido e a urina produzida. Antes de cada dia de treino, os atletas estavam hipohidratados (GEU > 1.020) e o consumo de água durante os treinos dificilmente era equivalente ao volume de líquido perdido pelo suor. Estava mais quente no primeiro dia de treino (31,5 ± 2,3°C e 43,4 ± 3,2% umidade relativa) e o suor produzido (2822 ± 530 mL) bem como o volume ingerido (1607 ± 460 mL) foram significativamente maiores do que nos outros dias. Os resultados revelaram também uma grande variabilidade na produção de suor entre os jogadores e uma correlação significante entre o suor produzido e o volume de líquido ingerido (r2 = 0.560 p = 0.010, dia 1; r2 = 0.445 p = 0.049, dia 2; r2 = 0.743 p
= 0.0001, dia 3). Conclui-se que a perda de líquidos pelo suor pode ser substancial em adolescentes que treinam futebol regularmente. Sugere-se aprimorar a percepção individual da perda de líquido pelo suor dos atletas a fim de evitar quadros de desidratação voluntária, bem como educar os jogadores a respeito da importância da hidratação antes de treinamento. E no terceiro artigo o objetivo foi avaliar o estado de hidratação pré-competição e o equilíbrio hídrico de jogadores de futebol durante uma partida em temperatura ambiente de 28°C (umidade relativa 45-55%). Foram mensurados o consumo de água e bebida esportiva e o volume de urina produzido. A gravidade específica da urina (GEU) e a variação da massa
corporal foram aferidas antes e após o jogo para estimar o nível de hidratação dos atletas. Os dados foram obtidos de 15 jogadores de futebol masculino (idade, 17 anos; estatura, 178 cm; massa corporal, 69,4 kg; índice de massa corporal, 20,1 ± 2,3 kg/m2; superfície de área corporal, 1,86 m2). Entretanto, como um jogador foi expulso durante a partida, os resultados apresentados são dos 10 jogadores que jogaram toda a partida e de 4 jogadores substitutos que não estiveram presentes em nenhum momento da partida. A média ± desvio padrão da produção de suor dos jogadores correspondeu a 2,24 ± 0,63 L e o volume de líquido ingerido foi de 1,12 ±
0,39 L (n = 10). Os valores correspondentes aos jogadores substitutos foram de 0,61 ± 0,12 L e 0,50 ± 0,10 L (n = 4). A GEU antes da partida (1020 ± 0,004) foi significativamente diferente dos valores pós jogo (1016 ± 0.004). Os dados mostram uma grande variabilidade no suor produzido e na ingestão de líquidos entre os jogadores durante a partida. A hidratação ainda é um desafio para certos atletas e educar todos os jogadores a respeito dos procedimentos de hidratação se revela extremamente importante.
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.
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.
Descrição
Palavras-chave
Hidratação, Futebol, Termorregulação, Desidratação, Exercício, Hydration, Soccer, Thermoregulation, Dehydration, Exercise
Citação
SILVA, Rafael Pires da. Fluid balance of soccer players during training and competition. 2010. 86 f. Dissertação (Mestrado em Aspectos sócio-culturais do movimento humano; Aspectos biodinâmicos do movimento humano) - Universidade Federal de Viçosa, Viçosa, 2010.