The first major line of sports drinks in the United States was pioneered in 1965 by a coach and a team of physicians from the University of Florida who formulated a carbohydrate-electrolyte beverage to help players who were being affected by heat and heat-related illnesses. Known as “Gatorade,” the drink, and others like it, has become quite popular among athletes.
As we sweat, our bodies lose fluid, which leads to dehydration, and eventually fatigue. This can be especially bad during the summer and in warmer climates. The electrolytes in sports drinks are supposed to promote rehydration. As for carbohydrates, they are utilized by our muscles to provide fuel, so replacing them during and after exercise may help maintain performance.
There have been plenty of claims made about the benefits of carbohydrate-electrolyte sports drinks, and plenty of marketing and celebrity endorsements to sell the stuff. But is it hype, or are sports drinks really better at hydrating you?
Researchers in Hong Kong completed a study that compared the rehydration achieved by drinking a carbohydrate-electrolyte beverage during a short-term recovery period after exercise-induced dehydration compared with drinking distilled water or sweetened lemon tea.
Now lemon tea after exercise may sound like an odd choice, but the authors say that it is one of the most popular commercial drinks in the Hong Kong market, and their goal was to differentiate this study from similar ones in the past by attempting to observe what occurs in the real world. However, they do mention that a limitation of this study is that the energy density, carbohydrate content, caffeine content and electrolyte composition are not completely comparable in the drinks. (The lemon drink contained caffeine and had carbohydrate content similar to high-sugar soft drinks.)
Thirteen well-trained male runners were involved in the study. On three separate occasions (separated by at least seven days), the subjects ran on a treadmill for 60 minutes at a speed required to elicit 70% of their maximal aerobic capacity. Prior to the run, they were required to fast overnight (10 to 12 hours) and consumed 500 ml of water before going to bed. On the morning of the study, they were weighed and blood samples were taken. Blood samples, expired-air samples and ratings of perceived exertion were also collected during the run.
Immediately after the run, the four-hour rehydration recovery period began. Subjects cooled down until they stopped sweating and were weighed again to determine their dehydrated weight, and more blood and air samples were taken.
During the recovery period, the subjects drank either a carbohydrate-electrolyte beverage, distilled water or lemon tea. Their total fluid intake was equivalent to 150% of the body weight lost during the run. The drink was consumed in six equal volumes at 30, 60, 90, 120, 150 and 180 minutes of the recovery period. The volume of urine produced by subjects was measured, and they were asked about their sensations of thirst, abdominal discomfort and stomach fullness at each of the intervals.
Finally, when the four-hour recovery period was over, they were weighed again, and the percentage of body weight loss that had been regained was used as an index of whole-body rehydration.
Sports Drinks Take First Place
When it came to the degree of rehydration produced after exercise, researchers found that the sports drink won.
After the run, the men had lost approximately 2 percent of their pre-exercise body weight. When the recovery period was finished, those who had drank the carbohydrate-electrolyte beverage regained, on average, 77.4 percent of the body weight lost versus 53.7 percent with the lemon tea and 45.5 percent with the distilled water.
The sports drink also had the least diuretic effect, i.e., the men produced less urine. Authors said the improved fluid retention was likely due to the carbohydrates stimulating greater intestinal water absorption and the sodium content in the drinks minimizing reductions in plasma osmolality, because while plasma volume was restored with the water group, the sports drink was shown to significantly expand the fluid content of the vascular space.
When it came to abdominal discomfort, both the water and sports drink groups reported less discomfort in the last two hours of the recovery period, but the lemon tea group reported higher stomach fullness, and some of the men said they felt bloated.
Are Sports Drinks Right for You?
Before you start slamming back the sports drinks, assess your exercise level. If you’re a truly active person looking to improve your performance and stay hydrated when you’re exercising intensely, a sports drink may be a good choice.
However, be aware that in addition to carbohydrates and electrolytes, these drinks contain sugar, sodium and calories. So they’re likely not a good substitute for water for low-impact or moderate-intensity exercisers. In those cases, such a drink is probably not needed and the additional calories are a clear downside. If you’re determined to get those electrolytes, though, most brands make a low-calorie version and there are some brands of water than contain electrolytes.
 Heung-Sang Wong, S. Chen, Y. (2011). Effect of a Carbohydrate-Electrolyte Beverage, Lemon Tea, or Water on Rehydration During Short-Term Recovery From Exercise. International Journal of Sport Nutrition and Exercise Metabolism. 21, 300-310.