Bolus Ingestion of Whey Protein Immediately Post-Exercise Does Not Influence Rehydration Compared to Energy-Matched Carbohydrate Ingestion

Nutrients. 2018 Jun 14;10(6):769. doi: 10.3390/nu10060769.


Whey protein is a commonly ingested nutritional supplement amongst athletes and regular exercisers; however, its role in post-exercise rehydration remains unclear. Eight healthy male and female participants completed two experimental trials involving the ingestion of 35 g of whey protein (WP) or maltodextrin (MD) at the onset of a rehydration period, followed by ingestion of water to a volume equivalent to 150% of the amount of body mass lost during exercise in the heat. The gastric emptying rates of the solutions were measured using 13C breath tests. Recovery was monitored for a further 3 h by the collection of blood and urine samples. The time taken to empty half of the initial solution (T1/2) was different between the trials (WP = 65.5 ± 11.4 min; MD = 56.7 ± 6.3 min; p = 0.05); however, there was no difference in cumulative urine volume throughout the recovery period (WP = 1306 ± 306 mL; MD = 1428 ± 443 mL; p = 0.314). Participants returned to net negative fluid balance 2 h after the recovery period with MD and 3 h with WP. The results of this study suggest that whey protein empties from the stomach at a slower rate than MD; however, this does not seem to exert any positive or negative effects on the maintenance of fluid balance in the post-exercise period.

Keywords: albumin; exercise; fluid balance; gastric emptying; maltodextrin; recovery; rehydration; whey protein.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Cross-Over Studies
  • Dehydration
  • Dietary Carbohydrates / administration & dosage*
  • Dietary Carbohydrates / pharmacology*
  • Exercise
  • Female
  • Fluid Therapy*
  • Humans
  • Male
  • Water / administration & dosage*
  • Water-Electrolyte Balance
  • Whey Proteins / administration & dosage*
  • Whey Proteins / pharmacology*
  • Young Adult


  • Dietary Carbohydrates
  • Whey Proteins
  • Water