Effects of skim milk and isotonic drink consumption before exercise on fluid homeostasis and time-trial performance in cyclists: a randomized cross-over study.

BACKGROUND: Hydration status affects endurance performance. Pre-exercise hydration recommendations target the consumption of high carbohydrate and sodium beverages. Milk, due to its carbohydrate and sodium content, may be considered an effective pre-exercise hydration beverage. PURPOSE: In a randomized cross-over trial, we compared the effects of an isotonic sport drink (SPD) with skim milk (SM) consumption before a race, on fluid homeostasis and time-trial performance in road cyclists. METHODS: Male road cyclists (n = 9; age, 26.8 ± 4.78 years) with 10.8 ± 8.56 years of experience in national competitions, consumed either SPD or SM in doses of 350 mL at 3 h and 350 mL at 1.5 h before a 18.6 km time-trial race. Measurements of body mass, urine specific gravity (USG), urine color and time-trial were compared between drinks (group; g) before and after the race (time; t). RESULTS: The two-way ANOVA showed no differences between SPD and SM in body mass (t, p < 0.0001; g, p = 0.89; t × g, p = 0.54), USG (t, p = 0.01; g, p = 0.63; t × g, p = 0.29) and urine color (t, p = 0.01; g, p = 0.54; t × g, p = 0.28) before or after race. Furthermore, no differences on water consumption during the race (p = 0.55) or time-trial performance (p = 0.84) were observed between trials. CONCLUSION: Current results may help athletes with different beverages preferences to increase their options of hydration strategies.

Drinking to thirst influences fluid replacement in adolescents judokas

AIM: The aim of this study was to examine the influence of the type of beverage and the use of thirst sensation to guide fluid replacement in the adolescent judokas. METHODS: Nine male judokas aged 10-16 (average age 11,8 ± 4,0 years old) were submitted to a standardized training of 90 minutes. In the first phase of the study, the athletes completed the training with ingestion ad libitum of different beverages: day 1 (water) and after 48 hours, day 2 (sports drink). In the second phase, after 7 days of first stage, the athletes completed the training with ingestion of water or sports drink, guided by thirst sensation. The total volume of liquids ingested (VI) during the training was quantified and the level of dehydration was determined by variation of body weight before and after training (∆W). At the end of each training, the athletes were asked about the training intensity to determine perceived exertion (PE). RESULTS: No differences were observed in weight loss (∆W) (range: -0,04 ± 0,4 to -0,69 ± 1,1 %) and perceived exertion (range: 3,2 to 5,0). The use of thirst sensation to guide fluid replacement reduced the total fluid intake when the beverage offered was the sports drink (no thirst vs. thirst sensation, 521,1 ± 290 vs 152,2 ± 187 mL - p=0,006). CONCLUSION: The results suggest that fluid replacement guided by thirst sensation can be influenced by the type of beverage offered.(AU)

Efeitos metabólicos de uma bebida esportiva cafeinada consumida durante uma partida de futebol / Efectos metabólicos de una bebida deportiva con cafeína consumida durante un partido de fútbol / Metabolic effects of a caffeinated sports drink consumed during a soccer match

The purpose of this study was to verify the effect of the intake of a caffeinated sport drink (CAFD) compared to a commercial carbohydrate drink (CHOD) on biochemical parameters and rate of perception exertion in youth soccer players. The experiment was setup in a double-blind crossover design where athletes consumed 5mL.Kg-1 body weight (BW) before the game and 3mL.Kg-1 BW every 15 minutes during the game. Intake of the CAFD resulted in increased blood glucose (BG) and blood lactate (BL) levels and average of maximum heart rate compared to consumption of the CHOD (p = 0.01). No difference was observed in the other variables. CAFD promoted greater plasmatic concentration of BG and BL compared with the CHOD. The CAFD did not increase the mobilization of free fatty acids, did not alter the plasma potassium concentration and was not able to reduce subjective perceived exertion.

O objetivo deste estudo foi verificar o efeito da ingestão de uma bebida esportiva cafeinada (CAFD) em comparação a uma bebida carboidratada comercial (CHOD) sobre parâmetros bioquímicos e a taxa de percepção de esforço em jogadores de futebol categoria juvenil. O desenho experimental foi duplo-cego cruzado, onde os atletas consumiram 5mL.Kg-1 de peso corporal (PC) antes do jogo e 3mL.Kg-1 PC a cada 15 minutos durante o jogo. A ingestão de CAFD resultou no aumento da glicemia (GS) e do lactato sanguíneo (LS) e do valor médio da frequência cardíaca máxima em relação ao consumo do CHOD (p = 0,01). Nenhuma diferença foi observada nas outras variáveis. CAFD promoveu maior concentração plasmática de GS e LS em comparação com o CHOD. A CAFD não aumentou a mobilização dos ácidos graxos livres, não alterou a concentração de potássio plasmático e não foi capaz de reduzir a percepção subjetiva do esforço.

El objetivo fue verificar el efecto del consumo de una bebida deportiva con cafeína (CAFD) frente a una bebida carbohidratada comercial (CHOD) sobre parámetros bioquímicos y el índice de percepción de esfuerzo percibido en jugadores de fútbol de la categoría juvenil. El diseño experimental utilizado fue de tipo doble-ciego cruzado, donde los deportistas ingieren 5mL.Kg-1 del peso corporal (PC) antes del partido y 3mL.Kg-1 PC a cada 15 minutos durante el partido. El consumo de CAFD produjo un aumento en la glucemia (GS) y del lactato sanguíneo (LS) y del valor medio de frecuencia cardiaca máxima frente al consumo de CHOD (p = 0,01). No hubo diferencias en las demás variables. CAFD produjo mayor concentración plasmática de GS y LS en comparación con la CHOD. La CAFD no aumento la movilización de ácidos grasos libres, no hubo alteración en la concentración de potasio plasmático y no fue capaz de reducir el índice de percepción de esfuerzo.