Athletes Run Risk of Overhydrating

A runner pours a bottle of water over his head.

There is such a thing as too much water; excessive intake can dilute levels of sodium in the blood. IStockPhoto hide caption

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Hydration Tips

University of Connecticut researcher Douglas Casa says people get into trouble when they try to follow set requirements for hydration.

  

Scroll below for more tips on how to figure out what's the right amount to drink for your body.

If you're training for a marathon or an Ironman, a hydration plan is important. Of course, there's the risk of dehydration. But athletes now know they can also get into trouble by drinking too much. Excessive water intake can dilute levels of sodium in the blood. The death of a 28-year-old woman following the Boston Marathon caught the attention of many runners and led to new research.

Experts advise long distance runners to replace the liquids they sweat out.

"Our goal is to try to keep someone from not getting dehydrated by more than 2 percent of their body weight," says Douglas Casa, a researcher at the University of Connecticut's Human Performance Laboratory.

One technique for calculating how much fluid you need is to get an accurate scale. Runners can weigh themselves before and after a run to determine how much water weight they've lost. If their weight drops by more than 2 percent, they have not consumed enough fluid.

Hyponatremia occurs when runners drink so much liquid that concentrations of sodium in the blood drop off. A study published in the New England Journal of Medicine last year tracked 488 runners who completed the Boston Marathon and found 13 percent of them had dangerously low blood salt levels.

The first symptoms that runners may notice is minor swelling in the hands. "They can't get their rings off, then they might get nausea and dizziness. They may not remember where they are" says Dr. Lewis Maharam, who directs the International Marathon Medical Directors Association.

Most runners get enough salt to restore normal levels by eating just one meal after a run, and most never need medical attention. But with a spate of reported cases of hyponatremia, Maharam's group has a new guideline for hydrating.

The recommendation is contrary to the old advice that runners should drink as much as they can stomach to prevent dehydration.

"The new research has shown that the body is a remarkable machine that actually tells you via thirst when you need fluid," says Maharam.

Performance-oriented runners may prefer the more exacting scale-weighing technique. Casa recommends that runners use that method until they start to get a good estimate of how much water they sweat out during a typical training run.

Everyday Hydration Tips

Dr. Douglas Casa, Director of Athletic Training Education in the University of Connecticut's Neag School of Education says people get into trouble when they try to follow set requirements for hydration. A magazine article that endorses eight glasses of water a day may not be right for you. Quench your thirst for information with Dr. Casa's tips on how to regulate your daily drinking.

Peek at Your Pee: Monitor its color. If it's light, like lemonade, you're doing pretty good. If it's darker, like apple juice, start gulping down liquids.

Step on the Scale: And do it both before and after exercising, to get a better sense of your individualized hydration needs. If you weigh more after a workout, chances are you drank too much while exercising. If you weigh much less, you may need to drink more. Experts recommend losing no more than 2 percent of your body weight during activity. Weighing the same before and after exercise, or slightly less, suggests you are an efficient hydrator.

Consider Sports Drinks: Because they replace some of the salts you lose when sweating, they're ideal for activities that last longer than an hour (for instance, hiking or biking treks) or even during very intense activities. Or if you're the kind of fanatic who's jogging in 110-degree heat.

Remember Chug Capacity: Recent studies show that coffee doesn't dehydrate, but Casa still doesn't recommend it for a workout; it's not the kind of fluid you can chug when you need to replace a lot of fluid in a short period of time.

(But Not for Beer!:) Alcohol does not leave you in the best possible state to recognize your fluid needs, prepare for the next bout of activity, or maximize fluid retention. Only use if stranded on an island with a case of beer, not for the purpose of fluid replacement.

Shun Sugar: Sodas, fruit juices and even beer have a higher level of sugar (which means more calories per serving) than most sports drinks or water. These drinks can rehydrate your body because they contain water, but their sugars give the stomach and intestines more to deal with; as a result, the fluids aren't absorbed into the body as quickly. It's fine to drink these beverages with meals and during leisure activities, but they won't keep you optimally hydrated during exercise.

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