It sounds simple. When doing exercise, you sweat. When doing intense or prolonged exercise, you sweat a lot. Sweat is made of water and electrolytes, such as salt, so exercise gradually depletes your body’s supply of them, as well as consuming energy. Therefore a sports drink made of water, electrolytes and sugar (for energy) must be good for you, and improve performance. Is there anything left to say?
There’s plenty. For one thing, people sweat at different rates, so some might not need to replace anything for a long time. For another, the science on electrolyte loss is hazy. “There’s some suggestion that it may lead to cramping,” says Dr Jo Corbett, a sports scientist at the University of Portsmouth, “although the actual mechanisms behind cramping possibly aren’t related to electrolytes. It depends who you speak to.”
Nor is the science of dehydration any clearer. Clearly, we need to drink, which is why we feel thirsty, but there is no consensus over when this reaches an unhealthy – or even unhelpful – level. Professor Tim Noakes at the University of Cape Town argues that over-hydration is the real problem, partly driven by the drinks industry. And last week, the Times reported that some research promoting the value of rehydration had been paid for by that internationally famous rehydrater, Coca-Cola.
As for the sugar, well, that’s a still-larger can of worms. People exercising for a very long time – say, at least an hour – will often benefit from a boost of carbohydrate. But these people only make up a small fraction of those targeted by the sports drinks market. “Most people probably aren’t going to become carbohydrate depleted in a short moderate-intensity gym session,” Corbett says. “If you haven’t had time to get a meal then a sports drink will give you a quick boost of energy but there are possibly better ways of doing that.” Moreover, if you’re exercising to lose weight, a sports drink may even be counterproductive. “Negative calorie balance is what you want if you want to lose weight,” Corbett says. “I see it myself. People at the gym walking while consuming these high-energy drinks. Potentially, they could be consuming more calories than they’re burning off!”
Jackie Newton, a former international marathon runner and now an athletics coach, has her own solution. Literally. “You can make your own drinks up,” she says. “If it’s a recovery drink, I recommend milk for the athletes I work with. It has the right amount of carbohydrate and protein. If you are looking for something to take during a long run, then some cordials, such as high juice, with maybe a little bit of salt in, if it’s a hot day.”
