Fast Rehydration Rate Helps To Keep Positive Body Fluid Balance Longer Time

Abstract

PURPOSE: To compare the effects of three different post exercise rehydration rates after exercise derived dehydration on body fluid balance and subjective feelings of thirstiness and bloating. METHODS: We evaluated five male college soccer players. They were weighted before performing a treadmill run to induce a ≈2% body weight loss by sweating. After the dehydration, subjects were rehydrated with 150% of their body weight loss with a carbohydrate electrolyte solution (5% CHO, 30 Na mEq/L). Subjects were assigned to one of three postexercise rehydration rates in a randomized, counterbalanced and crossover design. The postexercise rehydration rates consisted on drinking the whole fluid volume the first 30 minutes in 3 equal doses (H30), or the first 60 minutes in 5 equal doses (H60), or the first 120 minutes in 9 equal doses (H120) after dehydration. Subjects were weighted without clothes (after voiding their bladders and drying the skin with towels) each 30 minutes during a 240 minutes lapse. At the same time they answered a visual analogue scale to answer how thirsty and how bloated they felt at that moment. Results are presented as mean. A two-way repeated measures ANOVA was performed. RESULTS: Positive fluid balance in H30 was significantly higher than H60 and H120 at minute 30. H30 and H60 were higher than H120 at minute 60. H60 was higher than H120 at minute 90, but H30 was not different vs H60 nor H120. H30 kept a positive fluid balance for 2 hours, H60 for 1 hour, and H120 for 0.5 hours. Thirstiness was significantly lower in H30 than H120, but not to H60 at minute 30, no other difference was found. Bloating was significantly higher in H30 than H120, but not to H60 at minute 30, no other significant difference was found (Table 1). CONCLUSIONS: The H30 rehydration rate was effective to keep positive fluid balance for a longer period and to rapidly achieve positive fluid balance and decrease thirstiness acutely, however bloating may be a concern employing this rehydration rate.Table 1: Body fluid balance and subjective feelings of thirstiness and bloating by rehydration rateDifferent lowercase letters denotes significant differences (p<0.05) between rehydration rates at the same minute