LONDON: From eight glasses of water a day to protein shakes, we’re bombarded with messages about what we should drink and when, especially during exercise. But these drinking dogmas are relatively new.
In the 1970s, marathon runners were discouraged from drinking fluids for fear that they would slow them down. Now we’re obsessed with staying hydrated when we exercise; not just with water but with specialist drinks that claim to do a better job of preventing dehydration and even improve athletic performance. Yet, the evidence for these drinks’ benefits is actually quite limited. They might even be bad for your health.
Much of the focus on hydration can be traced back to the boom in road running, which began with the New York Marathon in the 70s. Sports and drinks manufacturers spotted a growing market and launched specialist products for would-be athletes.
The first experimental batch of Gatorade sports drink cost £28 to produce but has spawned an industry with sales of around £260 million (R4.3 billion) a year in the UK alone.
The key behind this huge rise in sports drinks lies in the coupling of science with creative marketing. One of the industry’s greatest successes was to pass off the idea that the body’s natural thirst system is not a perfect mechanism for detecting and responding to dehydration.
As a result, health-care organisations routinely give advice to ignore your natural thirst mechanism. Diabetes UK advises: “Drink small amounts frequently, even if you are not thirsty – about 150ml of fluid every 15 minutes.”
A British Medical Journal review screened 1 035 web pages on sports drinks and identified 431 claims they enhanced athletic performance for a total of 104 different products. More than half the sites did not provide any references – and of the references that were given, they were unable to systematically identify strengths and weaknesses. Of the remaining half, 84% referred to studies judged to be at high risk of bias, only three were judged high quality and none referred to systematic reviews, which give the strongest form of evidence.
One of the key problems with many of the studies is that they recruit highly trained volunteers who sustain exercise at high intensity for long periods. But the vast majority of users train for very few hours per week, or exercise at a relatively low intensity (for example, walking instead of running during a race). Importantly, as sports drinks rise in popularity among children, they may be contributing to obesity levels.
But endorsements by elite athletes and claims of hydration benefits have meant sports drinks have shrugged off unhealthy associations in many people’s eyes. What we can be almost sure about is that the drinks are not helping turn casual runners into Olympic athletes. In fact, if they avoided these sugar-laden drinks, they would be probably be slimmer and so faster. – The Independent