Sunday, January 14, 2007

The Winning Hydration Plan

The best way to prevent both dehydration and hyponatremia is to learn the right way to hydrate. Use the following tips to create your own hydration game plan:

Drink to Stay Hydrated, Don’t Overdrink — Your fluid-replacement plan should be designed to minimize loss of body weight so that you avoid dehydration during exercise but prevent weight gain from excess hydration during training or races. A good way to gauge your hourly sweat rate is to figure out the difference in body weight plus your drink volume. For example, if you lost 11/2 pounds (24 oz) during the run, and drank 12 ounces, you should try to drink 36 oz (24 + 12) each hour during similar-intensity training and racing. In this example, drinking 9 ounces every 15 minutes would do it. Overdrinking dramatically increases the risk of hyponatremia. It is vital not to overdrink before a race, because doing so can lower blood sodium even before the race begins. Also, don’t overdrink during or after the race!

Maintain a Salty Diet to make certain you replace all of the salt lost during training. During a
long race (e.g. more than four hours), consider eating salty snacks such as pretzels, especially if you are a salty sweater.

Favor Sports Drinks like Gatorade thirst quencher over water during long distance or intense
training and competition, to help keep your body hydrated, fueled and salted. The flavor of a sports drink will encourage you to drink enough to stay hydrated, the carbohydrate energy will fuel your active muscles, and the electrolytes will help replace some of what is lost in sweat. But remember don’t overdrink any fluid!

Recognize Warning Signs of both heat illness and hyponatremia and learn to distinguish
between the two. When in doubt, stop exercise, stop drinking and seek medical help fast.

Dehydration: Too Little of a Good Thing

Keeping the body properly hydrated with the right fluids is essential to safety and performance in a marathon. The fiercest competitor an endurance athlete faces is dehydration. The first obvious sign of dehydration is thirst, but things can quickly get worse. Dehydration not only hampers performance but also increases the risk of heat illnesses, such as heat exhaustion or potentially deadly heat stroke. The good news is that dehydration and heat illness can be prevented and performance improved simply by following the right fluid-replacement plan.

Signs of dehydration and heat illness can include:

• Headache
• Fatigue
• Dizziness
• Nausea
• Muscle cramps
• Weakness
• Irritability
• Vomiting
• Heat flush
• Abnormal chills

Hyponatremia: Too Much of a Good Thing

While it’s important to drink enough to remain hydrated, overhydrating by drinking too much can lead to a condition called hyponatremia, which is serious and sometimes deadly.

What is Hyponatremia?
Hyponatremia is a condition that occurs when the level of sodium in the blood drops below 135
mEq/L (138-142 is normal).* Symptoms of hyponatremia usually begin at blood sodium values
below 130, with values less than 120 resulting in a serious medical emergency. Exercise-related
hyponatremia is thought to be caused by overdrinking. Although rare, hyponatremia can result in seizure, coma, and death, so it is vital that athletes learn about the condition and how to prevent it.

Who’s at Risk for Hyponatremia?
Anyone who drinks too much and does not adequately replace the sodium that is lost in sweat
risks hyponatremia, but certain people should be especially careful:

• Endurance athletes – those exercising more than four hours

• Athletes on lowsodium diets

• Beginning marathoners who tend to run slowly and are hyper-vigilant about hydration

• Athletes who overhydrate before, during, and after exercise

• Salty sweaters – those athletes whose skin and clothes are caked with white residue after exercise

Symptoms of Hyponatremia Watch for a combination of these symptoms, especially if you or somebody you know is at a high risk for the condition.

• Rapid weight gain
• Swollen hands
• Confusion and feet
• Dizziness
• Throbbing headache
• Nausea
• Apathy
• Severe fatigue
• Cramping
• Lack of coordination
• Bloated stomach
• Wheezy breathing
• Seizure

Seek emergency care for hyponatremia victims. In most cases, they will be treated with:

• An intravenous solution of a concentrated sodium solution,
• A diuretic medication to speed water loss, and
• An anti-convulsive medication in the case of seizure.

The Runners’ Resource for Sports Medicine Montain SJ, MN Sawka, and CB Wenger. Hyponatremia associated with exercise: Risk factors and prognosis. Exerc Sports Sci Rev 29:113-117, 2001.