When the heat is on: Hydrate


— Summer in Steamboat Springs has been sizzling with temperatures in the high 80s and low 90s. The hot weather can be more than uncomfortable it may be detrimental to your health.

Staying hydrated is a top priority, whether we are exercising in the heat or merely trying to get through another scorching day. At this altitude, most sedentary individuals are not drinking enough fluids. When your body turns into a steam engine due to exercise, the recommended level of water intake rises sharply.

During moderate exercise in a hot environment, your body relies almost entirely on evaporative cooling, or sweating, to dissipate the tremendous amount of heat produced. The average runner or walker can lose up to a cup of water every mile through sweating. An athlete who is training loses considerably more. When this kind of demand is placed on the body's fluid reserve, it often results in dehydration.

Even a small amount of dehydration, equivalent to as little as 1 percent of body weight, impairs performance and the body's ability to regulate temperature. With prolonged exercise and excessive sweating, dehydration can progress to circulatory impairment and extremely elevated core temperatures.

Because blood provides a large portion of the water lost through sweating, the blood actually thickens as dehydration occurs. A serious condition called cardiovascular drift occurs when the amount of blood pumped per heartbeat decreases while the heart rate increases. Classic symptoms of serious dehydration include chills, shakiness, nausea, dry skin, disorientation and a throbbing pressure in the head.

Clearly, the replacement of fluids during exercise is important for the optimal functioning of our bodies. Yet most of us do not even replace 50 percent of the fluids we lose through sweating. To estimate how much water you need daily, divide your body weight by two and convert this number to ounces. Then add at least eight ounces for every 20 minutes of exercise.

High-calorie sports drinks may taste good, but you should reach for water first. Because sweat is less concentrated than body fluids, it is more important to replace water than electrolytes such as sodium and potassium. (A well-balanced diet usually replenishes the electrolytes lost during moderate exercise.) For exercise lasting less than an hour, ice cold water is an excellent choice. Cold water is more easily absorbed than either warm water or concentrated carbohydrate drinks.

A new form of fluid replacement called fitness water is ideal for hydration following moderate exercise. These drinks contain only about 10 calories per eight-ounce serving but still provide electrolytes and some vitamins. A small amount of electrolytes added to water contributes to more complete rehydration compared to water alone, because the sodium helps your body to retain more fluid. You can find fitness water in local health-food stores. Choose from several brands of bottled drinks or individual-sized packets in a variety of flavors.

Marianne Osteen has a master's degree in exercise physiology and is a counselor for the wellness program of the Yampa Valley Health Plan.


Use the comment form below to begin a discussion about this content.

Requires free registration

Posting comments requires a free account and verification.