Postexercise rehydration: potassium-rich drinks versus water and a sports drink
Alexandra Pérez-Idárraga, Luis Fernando Aragón-Vargas
Applied Physiology, Nutrition, and Metabolism, 10.1139/apnm-2013-0434
Fluid retention, thirst quenching, tolerance, and palatability of different drinks were assessed. On 4 different days, 12 healthy, physically active volunteers (24.4 ± 3.2 years old, 74.75 ± 11.36 kg body mass (mean ± S.D)), were dehydrated to 2.10% ± 0.24% body mass by exercising in an environmental chamber (32.0 ± 0.4 °C dry bulb, 53.8 ± 5.2% relative humidity). Each day they drank 1 of 4 beverages in random order: fresh coconut water (FCW), bottled water (W), sports drink (SD), or potassium-rich drink (NEW); volume was 120% of weight loss. Urine was collected and perceptions self-reported for 3 h. Urine output was higher (p < 0.05) for W (894 ± 178 mL) than SD (605 ± 297 mL) and NEW (599 ± 254 mL). FCW (686 ± 250 mL) was not different from any other drink (p > 0.05). Fluid retention was higher for SD than W (68.2% ± 13.0% vs. 51.3% ± 12.6%, p = 0.013), but not for FCW and NEW (62.5% ± 15.4% and 65.9% ± 15.4%, p > 0.05). All beverages were palatable and well tolerated; none maintained a positive net fluid balance after 3 h, but deficit was greater in W versus SD (p = 0.001). FCW scored higher for sweetness (p = 0.03). Thirst increased immediately after exercise but returned to baseline after drinking a small volume (p < 0.0005). In conclusion, additional potassium in FCW and NEW did not result in additional rehydration benefits over those already found in a conventional sports drink with sodium.
–> Sacana esta conclusão, né? Deveria ser o contrário: Bebidas esportivas não são melhores que água de coco natural…
Effect of milk consumption on rehydration in youth following exercise in the heat
Kimberly A. Volterman, Joyce Obeid, Boguslaw Wilk PhD, Brian W. Timmons
Applied Physiology, Nutrition, and Metabolism, 10.1139/apnm-2014-0047
Low-fat milk is thought to be an effective post-exercise rehydration beverage in adults; however, little is known about milk’s rehydration ability in children after exercising in the heat. This study tested the hypothesis that due to its electrolyte and protein content, skim milk (SM) would be more effective than both water and a carbohydrate/electrolyte solution (CES) in replacing body fluid losses in children following exercise in the heat. Thirty-eight (19 females) heat-acclimated pre- to early-pubertal (PEP, 7-11yrs) and mid- to late-pubertal (MLP, 14-17yrs) children performed three sessions in 34.5°C, 47.3% relative humidity consisting of 2 × 20-min cycling bouts at 60% VO2peak followed by consumption of either W, CES, or SM. Each beverage was consumed immediately after exercise in a volume equal to 100% of their body mass loss during exercise. Urine samples were collected before, during, and after exercise, as well as the 2h period following beverage consumption. On average, children dehydrated 1.3 ± 0.4%. Children ingested 0.40 ± 0.11 L (PEP) and 0.74 ± 0.20 L (MLP) of fluid. The fraction of the ingested beverage retained at 2h of recovery was greater with SM (74 ± 18%) than W (47 ± 26%) and CES (59 ± 20%, p<0.001 for both); and greater in CES than W (p<0.001). All participants were in a hypohydrated state after 2h of recovery, following the pattern SM<CES<W. In both PEP and MLP children, SM is more effective than W and CES at replacing fluid losses occurred during exercise in the heat.