In Brief:

The performance-depleting effects of dehydration on sports performance have long been known. But what’s the best kind of drink to take to prevent dehydration, maintain proper hydration during exercise and thereby maintain sports performance? That’s the question US scientists set out to investigate in a double-blind, randomised study on basketball players at Pennsylvania State University.

Fifteen basketballers (aged 12 to 15 years) underwent three separate two-hour exercise sessions in hot conditions with different drinking strategies:

• No drinks consumed leading to 2% dehydration (loss of fluid equivalent to 2% of body mass);
• Consumption of a 6% carbohydrate/electrolyte drink to maintain hydration levels (ie 0% dehydration);
• Consumption of a flavoured water placebo drink to maintain hydration levels, but with no added carbohydrate/electrolyte.

After each exercise session, there followed a recovery period after which the subjects performed an orchestrated sequence of continuous basketball drills designed to simulate a game (12-minute quarters with a 10-minute half-time). The researchers looked at a number of performance measures and component drills required during basketball; these included various individual and combined shooting percentages (3-point, 15-foot, free-throw shots), sprints (suicides, court widths), lateral movements (zigzags, lane slides), and defensive drills (combining lateral and front-to-back movement) times.

The results showed that, compared with the flavoured water drinking strategy, dehydration significantly impaired shooting ability (as expected), but that consuming the carbohydrate/electrolyte drink improved shooting compared with flavoured water. The same results were found with sprinting performance – ie drinking carbohydrate/electrolyte produced the quickest sprint times, plain water slightly slower times and dehydration markedly lower times (76 vs. 78 vs. 83 seconds, respectively). Moreover, the carbohydrate/electrolyte drinking strategy significantly improved total defensive drill times compared to no drinking.

This study provides persuasive evidence that using carbohydrate/electrolyte drinks to maintain hydration or rehydrate at half-time yields superior physical and skills performance to using just plain or flavoured water.

Med Sci Sports Exerc 2006 Sep; 38(9):1650-8