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The question

What kind of sports drink do I need to stay fuelled and hydrated in hot weather?

The answer

If you're an old-school type who thinks plain water is all you need, consider this puzzling fact: Rinsing your mouth with a drink containing carbohydrates will boost your athletic performance, even if you don't swallow and can't taste the carbs.

Of course, it's not just carbohydrates that you find in sports drinks these days. The latest offerings feature a bewildering array of formulations aimed at different sports and levels of activity, along with high-tech additives that purport to improve everything from alertness to metabolism.

But you should be wary of the hype surrounding these magic ingredients. The core of any sports drink remains simple, says University of Guelph researcher Lawrence Spriet. Here are the three key ingredients, in order of importance:


The first point is simple: "If you're engaging in physical activity you're going to lose fluids," says Dr. Spriet, who also serves as chair of the Canadian Gatorade Sports Science Institute's advisory council. If you lose 2 per cent of your body weight in the form of sweat, your performance will be noticeably impaired.

How much you sweat depends on the conditions, your exertion level and how heavy a sweater you are. The best way to check is to weigh yourself carefully before and after a session (remember to remove your sweat-soaked clothes). If you're losing too much weight, aim to drink a litre of fluid for each kilogram lost the next time you work out.


The second element is carbohydrates, which are typically found in sports drinks in the form of glucose or other easily digested sugars. The goal is to maintain blood-sugar levels and replace glycogen stores in hard-working muscles, which is essential in bouts of exercise lasting longer than an hour.

Scientists have long been puzzled about why carb-filled drinks also seem to help in shorter bouts of exercise, when energy stores shouldn't be an issue. A recent series of rinse-and-spit studies suggests that we have receptors in the mouth that send signals directly to the regions of the brain that regulate perception of fatigue.

Sports drinks traditionally contain about 6-per-cent carbohydrates, about half the level of a typical juice or soft drink. Any more than that slows down the rate at which the body can absorb fluid, according to a recent study by University of Birmingham researcher Asker Jeukendrup in the journal Nutrition & Metabolism.

Newer formulations such as Gatorade's G2 have cut the carb level to 3 per cent, which Dr. Spriet says is more appropriate for people exercising at moderate levels, who don't need the extra calories and sweetness.


Electrolytes, which replace the salts lost in sweat, help you retain the fluid you drink. In reality, though, these do more to help with post-exercise recovery than with performance during exercise.

"You have to be working really, really hard for the salt to matter," Dr. Spriet says.

In fact, Gatorade makes a little-known product called GatorLytes, which is essentially a sachet of salts that you add to regular Gatorade to up its electrolyte content - but it's only available to high-level sports teams, since typical athletes simply don't need it.

Beyond these three ingredients, the science gets a lot weaker. In fact, Gatorade's recent relaunch of its product line in the United States coincided with the decision to disband its U.S. scientific advisory panel. The new line boasts specialized formulations such as vitamin C to perk you up in the morning, B vitamins to help you metabolize energy, theanine to improve focus, antioxidants to "protect your body" and so on.

So far, Gatorade Canada has elected not to bring the full line of new products to this country - a decision that pleases Dr. Spriet.

"Everyone wants to make things more complicated, but there's a reason the basic formulation hasn't changed in years," he says. "It's fluid, sugar and salt. That's all it is - and it works!"

Alex Hutchinson blogs about research on exercise and athletic performance at