RESUMO
A good hydration status is important to the exercise performance and cognitive function of exercisers.The effective restoration of fluid balance after exercise is helpful to prevent dehydration,maintain body fluid balance,accelerate fatigue recovery,and enhance exercise performance.As the most effective sports nutrition supplement,sports beverage has different ingredients and formulas,and also has various effects.To provide clues for the development of sports beverage,this article reviews the types,components,effects,and mechanisms of sports beverage currently used in post-exercise fluid restoration.
Assuntos
Humanos , Bebidas , Desidratação , Exercício Físico , Hidratação , Esportes , Equilíbrio HidroeletrolíticoRESUMO
The effect of ingestion of a chilled carbohydrate and electrolyte solution on metabolic and hormonal responses and water-electrolyte balance was studied after two 5-km runs in hot outdoor conditions (Temp, 30.6-30.9°C ; humidity, 61.3-62.4%) . Eight healthy females (mean age 21.8 years) participated in : 1) a control experiment (Copt) with no fluid intake, 2) an experiment with 500 ml of tap water (WI), and 3) an experiment with 500 ml of sports beverage (SB) containing carbohydrate and electrolytes each of which were given after the 1st 5-km run, followed by a second 5-km run with an equivalent to 68.7-72.3% of VO<SUB>2</SUB>max. In the Cont, decreases in %ΔPV and blood glucose (BS) and increases in serum osmolality (Sosm), free fatty acid (sFFA) and plasma hormone concentrations related to regulation of the water-electrolyte balance in the body persisted after the 2 nd run. The intake of the sports beverage prevented hypoglycemia and ketoacidosis, as shown by an increase in sFFA and positive results for qualitative analysis of ketone body in the urine, and quick recovery of plasma volume following an endurance run under a hot environment. This study suggests that fluid replacement with a sports beverage containing carbohydrate and electrolytes was superior to plain water or no fluid ingestion in terms of metabolic and hormonal responses and the recovery of plasma volume and elevated rectal temperature following an endurance run under hot conditions.
RESUMO
The purpose of the present study was to assess the effect of commercial sports beverage intake after a thermal exposure on water-electrolytes balance.<BR>Nine healthy male volunteers with a mean age of 26.4 years, not heat acclimated, participated in a control experiment where no fluid was given (C experiment) . Five of them were given 500ml isotonic sports beverage containing Na<SUP>+</SUP>, K<SUP>+</SUP>, Cl<SUP>-</SUP>and glucose (S. B experiment) and/or 500 ml tap water (Wa experiment) immediately after sauna exposure. The nude subjects were exposed to a sauna with 65 to 70°C (r. h. 50 to 60%) for 30 min.<BR>Serum protein, electrolytes (Na<SUP>+</SUP>, K<SUP>+</SUP>, Cl<SUP>-</SUP>), creatinine, plasma aldosterone (Ald), and catecholamines concentrations and excretions of electrolytes and aldosterone into urine were measured before, and 3, 30, 60, and 120 min after the sauna. Serum and urinary osmolalities, blood pressure, rectal temperature (Tr), heart rate, oxygen consumption and weight loss were also measured.<BR>Body weight loss ranged from 50 to 750g. Serum protein, electrolytes and Ald concentrations increased significantly after the sauna. The enhanced levels of these variables and the depression of urine volume, urinary Na<SUP>+</SUP>excretion were maintained throughout the 2h recovery period in C experiment. Hydration associated with a reduced concentration of serum protein and electrolytes was observed at 30 min in S. B, at 60 min in Wa, and a dehydration occured again at 120 min both in S. B and Wa. A peak of urine volume was observed at 60 min in S. B and at 120 min in Wa during recovery. Free water clearance (C<SUB>H2O</SUB>) was -0.98 ml/min/100 ml GFR (Ccr) prior to the exposure. With no fluid administration after the sauna, an excess in negative water balance remained throughout the 2 h recovery. But C<SUB>H2O</SUB>changed from negative to positive at 60 and 120 min after sports beverage and/or water loadings.<BR>A significant elevation of % TRNa (0.33 to 1.14%) was maintained after the sauna in both C and Wa experiment. Plasma Aid concentration and excretion of Aid in urine after the exposure were higher in both C and Wa than in S. B experiment. The increased Tr did not return to the initial level throughout the recovery. No significant differences were observed among the three experiments in heart rate and blood pressure as well as Tr.<BR>The data indicate that salt deficit due to the sauna exposure was attenuated, but not prevented, by sports beverage intake, although the Aid secretion was alleviated. It is suggested that an over loading of sports beverage or water (i. e. 500 ml VS 50 to 750 g weight loss) leads to a marked and prompt water-diuresis, and to another dehydration. The increase of Tr as well as a partly salt deficit can be related to the rises in Ald secretion still observed at 2 h recovery.