Wednesday, July 12, 2006


The heat and humidity is getting pretty bad. Welcome to Michigan. The following article by Melissa Gerharter about hydration provides some useful insights.


When it comes to keeping your body hydrated many questions may arise. How much fluid do I need? How much is too much? What should I be drinking?

If you are a physically active person chances are your thirst mechanism is not accurate so body fluid balance is often compromised. Although fluid needs are individual, the AI(adequate intake) is 3.7 liters for males and 2.7 liters for females. This would include the water that we intake from food as well as fluids. About 20% of the water that we take in comes from food and the other 80% comes from fluids. The absolute minimum for a sedentary individual is no less then 1 liter per day. Again, fluid balance is going to be different for each individual dependent on how much they sweat during activity.

Hydration before exercise is very important to assure optimal performance. Proper hydration before exercise can help lower your body’s core temperature, lower your heart rate as well as lowering your perceived exertion. It is recommended to drink 1oz of fluid for every 10lbs of body weight within two hours before exercise.

During exercise hydration is equally important. It is important to drink fluids every 10-30 minutes with the idea of drinking before you get thirsty. If you are an excessive sweater replacing your electrolytes by drinking a sports drink is imperative during long distance events.

After exercise it is important to replace all the fluids that you lost during exercise. The most accurate way to do this is to weigh yourself before and after to determine what you lost and replace these lost fluids.

Is it possible to drink too much water? In most cases the only disadvantage in drinking too much water is frequent trips to the bathroom. However, in some situations drinking too much water can become deadly if the body fluids become diluted creating a sodium imbalance. People at risk for hyponatremia (low level of blood sodium) are those who limit their sodium intake and exercise for more then four hours in the heat. Symptoms include fatigue, nausea, headaches, confusion and a lack of coordination.

The general guideline is that water will work to keep you hydrated. Unless you are participating in endurance activities lasting longer then one hour sports drinks aren’t necessary. Keep in mind that you need to find what works for you and stick with it.

Drink up!

Melissa Gerharter, MS

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