Effect of whey protein isolate on rehydration after exercise

Area of Science:

• Exercise Physiology
• Sports Nutrition
• Human Physiology

Background:

• Limited research exists on the isolated effects of protein on post-exercise rehydration.
• Previous studies focused on combined carbohydrate-electrolyte and protein drinks.

Purpose of the Study:

• To investigate the isolated effect of whey protein isolate on rehydration following exercise-induced dehydration.
• To determine if whey protein isolate impacts fluid retention and balance.

Main Methods:

• Ten subjects underwent two dehydration trials via cycling in heat.
• Rehydration involved ingesting 150% of body mass loss over 1 hour with either mineral water or mineral water plus 20 g/L whey protein isolate.
• Blood and urine samples were collected pre- and post-exercise, post-rehydration, and hourly for 4 hours.

Main Results:

• No significant differences were observed in total urine volume, drink retention, or net fluid balance between water and whey protein isolate trials.
• Plasma volume was maintained longer with whey protein isolate (3-4 hours post-drinking).
• Plasma albumin content increased with whey protein isolate intake.

Conclusions:

• Ingesting 20 g/L whey protein isolate does not impede or improve rehydration when 150% of sweat losses are consumed within 1 hour.
• Post-exercise protein intake, like whey protein isolate, can be incorporated for recovery and adaptation benefits without compromising rehydration status.