Dehydration Symptoms, Causes, Prevention and Treatment

Runner Taking a Water Break
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If you don't hydrate properly before, during, and after your run, you may be at risk for dehydration. Here are the symptoms to look out for and how to prevent getting dehydrated: 

Symptoms:

Early signs of dehydration include increased thirst; nausea; dry mouth; headache; fatigue; reduced urine output, with dark yellow urine. Symptoms of moderate dehydration include extreme thirst; dry appearance inside the mouth; decreased urination, or lightheadedness.

Serious dehydration can lead to cramps, chills and disorientation.

Cause:

Not drinking enough to replenish water excreted through sweating, breathing, and eliminating waste.

Prevention:

The easiest way to avoid heat disorders such as dehydration is to keep your body hydrated. This means drinking fluids before, during and after exercise. You should make sure that you're starting out your runs well-hydrated. The easiest way to make sure you're hydrated is to do a urine test. Go to the bathroom before you head out for your run. If your urine is pale yellow, that means you're well-hydrated. If it's dark -- like apple juice -- you need to drink more before you start running.

How much to drink while running?  The current fluid recommendations for runners say that they should "obey your thirst" and drink when their mouth is dry and they feel the need to drink. Drinking more or less than that can hurt your performance and lead to problems.

Make sure you have access to fluids if exercising longer than 30 minutes. During longer workouts, some of your fluid intake should include a sports drink (like Gatorade) to replace lost salt and other minerals (electrolytes). The electrolytes will help prevent hyponatremia (when you take in more water than you're sweating out and your water/sodium balance is off) and maintain better body water distribution.

Trying sipping rather than swigging your fluids. If you try to gulp 16 ounces of water or Gatorade all at once, you may feel uncomfortable as it's sloshing around in your stomach.

Make sure you always keep the conditions in mind when you're running. When it's extremely hot and humid, you're going to drink more than you usually do. If the conditions have you concerned about possible dehydration, slow your pace down so that you sweat at a lower rate.

Rehydrating after a run is also a critical step that some runners skip and end up suffering from dehydration hours after they've  finished their run. How much to drink after your run varies widely depending on your fitness level, the weather, and your sweat rate. Again, the urine test works well here. When you're rehydrated, your urine will be the color of lemonade.

More: Tips for Preventing Heat-Related Illnesses

Treatment:

The only effective treatment for dehydration is to replace lost fluids. You should keep drinking fluids until you urinate. If your urine is a light lemonade color, that means you're re-hydrated.

If it's a dark yellow, keep drinking. Someone who is severely dehydrated may need intravenous hydration, which can give them water and essential nutrients faster than drinking.

Sources:

"Exercise and Fluid Replacement", ACSM Position Stand, American College Of Sports Medicine, Medicine and Science In Sports & Exercise, 2007.

MayoClinic.com - Dehyration

Tamara Hew-Butler, DPM, Joseph G. Verbalis, MD, and Timothy D. Noakes, MBChB, MD, DSc, "Updated Fluid Recommendation: Position Statement From the International Marathon Medical Directors Association (IMMDA)," Clinical Journal of Sports Medicine, 2006;16:283–292)

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