Protein Added to a Sports Drink Improves Fluid Retention

Abstract

The purpose of this study was to compare fluid retention of carbohydrate plus protein, a carbohydrate-only, and water following 2.5% body weight (BW) loss. Thirteen subjects dehydrated to 2.5% of BW, then ingested a CHO (6%) plus protein drink (1.5%; CP), a 6% CHO drink, or water (WA) at a volume equal to BW loss during a 3-h recovery. Fluid retention was significantly greater for CP (88 +/- 4.7%) than CHO (75 +/- 14.6%), which was greater than WA (53 +/- 16.1%). Serum and urine osmolalities were greater for CP (284.7 +/- 5.0; 569.4 +/- 291.4 mOsm/kg) than CHO (282.6 +/- 5.2; 472.9 +/- 291.5 mOsm/kg) which were greater than WA (280.6 +/- 5.9, 303.7 +/- 251.5 mOsm/kg). Results indicate that fluid retention for CP was 15% greater than CHO and 40% greater than WA. Water ingestion led to a dilution of the serum and resulted in only 53% fluid retention.

Effect of whey protein isolate on rehydration after exercise

“…There The difference in findings between the studies of Seifert et al (2006) and James et al (2012) might be explained by the difference in rehydration drink volume ingested (100% vs. 150%) or the fact that the energy density of the rehydration drinks was either matched (James et al 2012) or unmatched (Seifert et al 2006). In the present study, the rehydration drinks were not matched for energy density and were ingested in a volume equivalent to 150% of subjects sweat losses, which is in line with current recommendations (Sawka et al 2007).…”

“…Using G*Power 3.1.6 (Faul et al, 2009) and the data of Seifert et al (2006), an α of 0.05 and statistical power of 0.8, it was determined that nine subjects would be required to reject the null hypothesis.…”

“…Milk protein is comprised of ~80% casein proteins and ~20% whey proteins and whilst the post-exercise rehydration effects of casein are presently unknown, two studies have examined the effects of whey protein (Seifert et al 2006;James et al 2012). Seifert et al (2006) reported that after exercise in the heat, a greater proportion of a commercially available 60 g·L -1 carbohydrate, 15 g·L -1 whey protein drink was retained compared to a commercially available 60 g·L -1 carbohydrate drink or bottled water.…”

“…Seifert et al (2006) reported that after exercise in the heat, a greater proportion of a commercially available 60 g·L -1 carbohydrate, 15 g·L -1 whey protein drink was retained compared to a commercially available 60 g·L -1 carbohydrate drink or bottled water. In contrast, James et al (2012) reported no difference in drink retention between a 65 g·L -1 carbohydrate drink and a 50 g·L -1 carbohydrate, 15 g·L -1 whey protein isolate drink, when drinks were ingested in a volume equivalent to 150% of sweat lost during exercise and matched for energy density and electrolyte concentrations.…”

Effect of whey protein isolate on rehydration after exercise

“…We recently reported that when added in an energy matched fashion and when drinks are ingested in a volume equivalent to 150 % sweat loss, addition of milk protein (1) to a carbohydrate-electrolyte drink enhances rehydration, whilst the addition of whey protein isolate does not (2) . In contrast, Seifert et al (3) reported that when a volume of 100% sweat loss is ingested, the addition of whey protein to a carbohydrate-electrolyte drink in a non-energy matched fashion enhances rehydration. These studies have only examined the effect of protein addition to carbohydrate-electrolyte drinks and thus the purpose of the present study was to determine if whey protein effects rehydration in isolation with a rehydration volume sufficient to fully restore fluid balance after exercise (150 % sweat loss).…”