TOOLBOX: Hydration “Re-Reloaded”
It may not be this scorching hot summer of last year, but it’s still summer and hot in most places! It’s never a bad time to take a refreshing pause and quench our thirst for knowledge in the area of staying hydrated – you know – drinking enough of the right stuff…
This article first ran July 29, 2003
The blazing hot weather of the Le Tour has broken, but it’s still broiling hot over most of North America. And thanks to Lance’s little experience with dehydration during the first time trial, there’s been lots of feedback from our recent series on hydration (read Hydration Part I here) and drink composition (read Hydration Part II here) in this week’s Toolbox. Let’s take yet another dip into the drink…
A sports doctor and cyclist told me he mixes a teaspoon of sugar, a pinch of salt, and squeezes in a couple of drops of fresh orange or lime for taste in a water bottle for rides over an hour. He says this mixture was used for his riders in major stage races like the Giro. This mix is what WHO recommends for rehydrating people with dysentery and the like. I’ve used this numerous times without any stomach upset.
Thanks for the great article on hydration. I was surprised to hear you say that all sports drinks are the same and to make your choice based on what tastes and works best for you. Everything else I’ve read always talks about maltodextrins being best, sucrose, fructose and glucose being worse. Most of this is based on the insulin response with, as I understand it, long chain CHOs not causing the insulin spike and removing glucose from the bloodstream as a result. Could you explain your thinking to me in a bit more detail? Thanks.
In your article you mention that fructose won’t digest easily because it takes longer to break downIsn’t fructose a simple sugar, ie, one from natural sources like oranges, apple, grapes, pinapples, melons, comquats etc? Therefore, won’t it be absorbed more readily than say dextrose, or fructose/dextrose combinations? These will take more time to break down because they’re complex sugars, thus resulting in slower absorption. YES!? In some races, I tend to cramp near the end because of electrolyte imbalance and my sprint is ruined (‘course I can’t sprint anyway so no-one really notices!)
Stephen’s teammate Jamie
Great questions all! Let’s take a look at two big issues when it comes to hydration: 1) “Can you drink too much?” and “Home brew or commercial drinks?”
Drinking Too Much?
We all saw that Lance did not drink enough, but can you actually drink too much? Dr. Tim Noakes, a top exercise physiologist from South Africa, is convinced that one of the big dangers with hydration is drinking too much during events, possibly leading to a severe dilution of the electrolyte concentration in the blood called hyponatremia. He cites his work with a lot of elite athletes who perform best by drinking only sparingly during marathons and ultra-endurance races. Hyponatremia can be especially problematic if water or very dilute drinks are consumed in huge quantities. The problem is that the symptoms of hyponatremia are very similar to those of heat exhaustion or heat stroke, and care must be taken by medical personnel at sporting events to make sure that a hyponatremic individual isn’t just given a lot more water to drink!
While I agree in principle with Dr. Noakes that drinking too much dilute drinks can be just as bad as not drinking enough, I would generally recommend erring on the side of drinking more rather than less. If you analyse the case histories of the people who come down with hyponatremia, they tend to be really off the scale in terms of the truly immense volumes of water that they consume. It’s actually really difficult to drink as much as you need to in order to risk hyponatremia, and the risk and prevalence of dehydration are much greater. So keep chugging!
Home Brew or Not?
This is really the billion-dollar holy grail for sport drink companies. You will read tons of research in scientific journals and even more conflicting marketing hype from different companies. But when you boil down all the research, I will again repeat my mantra that the only relevant goals when it comes to hydration are: 1) Make sure you maintain adequate hydration prior to exercise; 2) A sports drink should have water, fairly simple carbohydrates, and some sodium; and 3) The ideal sports drink is one that you like, want to drink a lot of, and doesn’t cause stomach cramps.
There are certainly slight differences in the rate of emptying and absorption of maltodextrin, dextrose (table sugar to you and me), and fructose, but they really are slight shades of grey compared to the essential big picture of drinking enough of something that tastes good. Again, the ideal composition will change depending on the weather (generally your tolerance for sweetness decreases with heat) and the type of event. Ultra-events like RAAM or randonneurs will require more complex carbohydrates and even proteins and fats in liquid form because you’re spending endless hours exercising and cannot refuel adequately with solid foods.
Many riders also like a very sugary and caffeinated drink like de-fizzed cola near the end of a race for a jolt prior to the finish line. Because you’re exercising and burning a lot of carbohydrates anyway, the body doesn’t respond with the huge insulin spikes that may occur during rest (unless you’re also stuffing a big chocolate cupcake into your mouth during the ride!). Also, the rate of absorption is slowed during exercise, again decreasing the risks of insulin spikes and therefore the importance of things like the glycemic index (future article).
This leads again to the big rule that I keep harping about. Namely, experiment with different drinks to find what works for you. Then make sure you practice your hydration plan!
Keep on drinking and thanks for writing!
Stephen Cheung is an Associate Professor of Kinesiology at Dalhousie University in Halifax, Nova Scotia, Canada, with a research specialty in the effects of thermal stress on human physiology and performance. He has been an avid roadie since beginning university in the mid-eighties, and still has non-indexed downtube shifters on his winter bike and wool jerseys hanging in his closet. He can be reached for advice or comments at [email protected]