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.

中文翻译：

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运动前饮用脱脂牛奶和等渗饮料对骑自行车者的体液稳态和计时表现的影响：一项随机交叉研究

背景水合状态影响耐力表现。运动前补水建议针对的是高碳水化合物和高钠饮料的消费。牛奶，由于其碳水化合物和钠含量，可被认为是一种有效的运动前补水饮料。目的在一项随机交叉试验中，我们比较了等渗运动饮料 (SPD) 与赛前饮用脱脂牛奶 (SM) 对公路自行车手的体液稳态和计时赛表现的影响。方法 男性公路自行车手（n = 9；年龄，26.8 ± 4.78 岁）在全国比赛中拥有 10.8 ± 8.56 年的经验，在 18.6 公里前服用 SPD 或 SM，3 小时 350 毫升，1.5 小时 350 毫升计时赛。比较不同饮料之间的体重、尿液比重 (USG)、尿液颜色和计时的测量值（组；g) 赛前和赛后（时间；t）。结果 双向方差分析显示 SPD 和 SM 在体重 (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) 和尿液颜色 (t, p = 0.01; g, p = 0.54; t × g, p = 0.28) 赛前或赛后。此外，在比赛期间（p = 0.55）或计时赛表现（p = 0.84）在试验之间没有观察到差异。结论 目前的结果可以帮助具有不同饮料偏好的运动员增加他们的补水策略选择。此外，在比赛期间（p = 0.55）或计时赛表现（p = 0.84）在试验之间没有观察到差异。结论 目前的结果可以帮助具有不同饮料偏好的运动员增加他们的补水策略选择。此外，在试验之间没有观察到比赛期间的用水量 (p = 0.55) 或计时赛表现 (p = 0.84) 存在差异。结论 目前的结果可以帮助具有不同饮料偏好的运动员增加他们的补水策略选择。