Data calculations and statistical analysis
All the participants achieved a positive net fluid balance of 1000(g) following the fixed volume of the fluid ingested (1L). Net fluid balance each hour was then calculated from the total mass of urine (cumulative urine output) that had been collected to that point. Electrolyte balance on each trial was determined by subtracting the amount of sodium or potassium excreted through urine from the total sodium or potassium ingested within the test beverage.Urine creatinine was used to estimate GFR (Levey et al. Cumulative urine outputs, by beverage and between groups, were compared using repeated measures ANOVA. Participant characteristics were analysed by paired t-tests. Data for net fluid balance, and electrolytes were analysed by 3-way ANOVA (beverage x time point x age group) to identify within and between group differences. All statistical analyses were completed using a statistical software package (IBM SPSS Statistics, V.23). Statistical significance was accepted at 