The goal of post-exercise rehydration is to regain fluid balance after water and electrolyte losses in sweat. Ingested fluid should favor a large fluid retention; coconut water has been used as a reasonably good option for this purpose.
PURPOSE: To evaluate fluid retention and sensory perceptions of natural and conventional drinks.
METHODS: On three different days, one week apart, 11 healthy people, female (5) and male (6), physically active, young (22±2 y.o.) students were dehydrated to 1.84%±0,6 body mass (mean ± standard deviation) by exercising in a climate-controlled laboratory (32SymbolC dry bulb, 60% RH). Each day they were rehydrated with one of three beverages, in random order: fresh coconut water (CW), plain water (PW) and a sports drink (SD), using a volume equivalent to 120% of weight lost during exercise, distributed in 4 equal aliquots, one every 15 minutes. Before drinking each volume, participants were asked about perception of thirst, nausea, fullness, stomach ache, and urge to defecate; after completing each volume, they reported ratings of flavor, sweetness, and general acceptability of the drink. Participants were then monitored for three hours, collecting urine every 30 minutes. Comparisons were made with repeated-measures ANOVAs for fluid retention, total urine, and partial times subjective measures and urine production.
RESULTS: Urine volumes were higher (p<0.01) for PW (624±183 mL) than for the other two drinks, but CW and SD were not significantly different (390±73 vs. 416±200 mL, respectively; p>0.05). Accordingly, CW was as effective as SD in terms of fluid retention (71.05±7.9 vs 71.29±14.26% of ingested fluid, p>0.05); both were better (p=0.001) than PW (55.95% of ingested fluid). There was no interaction between beverage and perceived tolerance measures during rehydration (p>0.05), but the overall acceptability was greater for SD compared with CW and PW (4±0.1, 3.0±0.3 and 3.2±0.2, p=0.007).
CONCLUSIONS: Coconut water showed fluid retention similar to a sports drink and is well tolerated, but the sports drink received higher acceptance ratings. Coconut water may be recommended for post-exercise rehydration provided it is well accepted and available.
