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CLIF Blog

Sep. 24, 2009
Fluid Replacement: A Tricky Balance
Many of our ultra-endurance athlete friends struggle with cramping issues that can put a serious wrench in their performance. In my opinion, hydrating properly is one of the most challenging aspects of being out on the road, trail, or in the water for more than an hour or two. You may have heard that dehydration of even 2-3% can slow you down. Dehydration and sodium loss is also the number one cause of cramping! When fluid and sodium losses are high, cramps can be on the menu. Replacing fluid and sodium is one of the trickiest tasks for an ultra-endurance athlete especially if it’s hot and humid.

So what’s the best approach to staying hydrated and preventing cramps?

Well, if you go looking for specific guidelines you won’t find them. Sports Dietetics USA and the American College of Sports Medicine will give general guidelines that simply say “replace fluids and eat salty foods.” Why so vague? Well, because every athlete’s body is different and even every event is different. Fluid and sodium replacement is NEVER one size fits all and ranges of need are huge.

If you’re an ultra athlete it’s time to learn even more details about your body and check out your sweat rate. Simply weigh yourself before training and again after. You need to replace 16-24 oz for every pound lost. This can give you an idea of whether you’re meeting your body’s specific needs during the race. I’ve seen ultra-endurance athlete sodium needs range from 250mg-700mg per hour.

Consuming consistent amounts of sodium every hour, whether its drinking a sports drink, having some salty food, or even taking salt tabs, can help replace sodium losses in sweat. It’s nearly impossible to replace all you lose during a race but the more you minimize losses through replacement, the better the performance. Of course, there are the variables that can throw off even the best laid out plans like air temperature, humidity, and intensity. Still, as long as you have a plan, you’ll be able to better “weather” these variables.

Cramping is sometimes blamed on depletion of potassium and other minerals like calcium and magnesium. Yet, very little potassium, calcium and magnesium is actually lost during exercise. Also, these substances are abundant in most diets, making deficiencies in these three vitamins and minerals rare. If cramps are your menace, tweaking your hydration and sodium replacement plan will get you back in action.

Hopefully this gives you some ideas as you prepare for you next race.
Posted by:
Tara, the RD
Category:
Food Matters
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We like getting our heart rates up, taking a big breath of fresh air, savoring delicious food. But we also love telling stories and here's where we type 'em up. (BTW, it works both ways; leave a comment—please and thank you.)

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