Sports Drinks
EAS sports drinks are available in the on-line shop:
Comparison of 4 drinks - rehydration in the heat
This study compared the ability of 4 drinks of different composition to rehydrate subjects who voluntarily dehydrated by 1.94% body-mass following an intermittent exercise protocol (Shirreffs et al. (2007) Rehydration After Exercise in the Heat: A Comparison of 4 Commonly Used Drinks. IJSNEM, 17(3), June, 2007.). The subjects consumed a volume equivalent to 150% body-mass loss of either:
- a carbohydrate-electrolyte solution (Gatorade)
- a carbonated apple juice-water solution (4 parts carbonated water:6 parts apple juice)
- a mineral water (either Evian or San Benedetto)
The study period lasted 4 hours post exercise. At the end of this time, the subjects were still in a significantly lower hydration state than pre-trial following consumption of the mineral waters and the apple juice solution. However, the carbohydrate-electrolyte drink trial resulted in subjects being in the same hydration status as before exercising after 4 hours. Subjects remained in negative sodium balance throughout the trial period regardless of the type of drink consumed and only the apple juice solution led to a positive potassium balance at the end of the trial.
The researchers concluded that there is a limited range of commercially available drinks which have a composition suitable to achieve rehydration and replenishment of essential electrolyte levels.
Protein in sports drinks improves fluid retention
A study from 2006 compared fluid retention following consumption of a 6% carbohydrate + 1.5% protein drink (CP), a 6% carbohydrate drink (C) or water (Seifert et al. (2006) Protein Added to a Sports Drink Improved Fluid Retention. IJSNEM, 16(4), Aug, 2006.). 13 subjects dehydrated by 2.5% body weight and then consumed a volume of fluid equal to that of water loss over a 3 hour period.
As expected, fluid retention was worst in the water trial. Interestingly, the CP drink resulted in a 15% greater fluid retention than the C drink suggesting that the addition of protein to a carbohydrate sports drink may aid rehydration.
Chocolate milkshake as post-exercise drink?
Good news for chocolate lovers - it seems that chocolate milkshake may be an effective recovery aid (Karp et al. (2006) Chocolate Milk as a Post-Exercise Recovery Aid. IJSNEM, 16(1), Feb, 2006.). 9 subjects completed 3 testing sessions composed of an interval workout, a 4 hour recovery period and an endurance trial to exhaustion - each session was separated by 1 week. During the 4 hour recovery period, subjects received iso-volumic amounts of either low-fat chocolate milk (CM), a carbohydrate-electrolyte drink (CE) or a carbohydrate replacement drink (CR). Carbohydrate content was 70g in CM and CR but just 30g in CE.
Time to exhaustion and total work during the exhaustion trial were significantly greater for the CM and CE trials as compared to the CR trial. This led researchers to suggest that chocolate milkshake with it's high carbohydrate and protein content may be an effective post-exercise recovery aid and an alternative to commercially available carbohydrate-electrolyte drinks.
Carbohydrate + protein for recovery from running
To determine whether the addition of protein or increasing carbohydrate intake had differing effects on recover, this study used 8 runners as subjects (Warren et al. (2005) Recovery from Run Training: Efficacy of a Carbohydrate-Protein Beverage? IJSNEM, 15(6), Dec, 2005.).
The subjects performed a 21km treadmill run followed by a treadmill run to fatigue after which they consumed either a 6% carbohydrate drink, an 8% carbohydrate + 2% protein drink or a 10% carbohydrate drink. After 2 hours of recovery, the 21km run and run to fatigue were repeated and, 24 hours later, the subjects performed a 5km time trial.
Results showed that creatine kinase (marker of muscle damage) levels were no different between trials but perceived muscle soreness was lower in the protein trial than in the high carbohydrate trial. In summary, the authors concluded that the additional calories from protein or carbohydrate had no effect on subsequent performance but the addition of protein may benefit through lower levels of muscle soreness.
EAS sports drinks are available in the on-line shop: