BE IN THE KNOW ABOUT H2O
By Margaret Gutgesell, MD, PhD

One of the reasons most folks choose to live in Grand County is because they love to be active, and active lifestyles at this elevation require adequate levels of water in the body, or hydration. Our blood is approximately 80 percent water, and muscle and bones contain about 75 percent of this simple molecule. Due to the simple process of breathing, even more body water is lost in cool mountain air. Add exercise, with faster breathing rates and perspiration, and your athletic performance can suffer if you don’t add water.

Classic symptoms of dehydration are thirst, dizziness, headaches, weakness and rapid heart rate. More severe symptoms include mental confusion, exhaustion and collapse.

On arriving at altitude, drink lots of fluids (avoiding alcohol) for the first 48-72 hours, even if you’re not physically active. Fluid replacement needs depend on type, duration and intensity of exercise, as well as weather conditions. If you overdress, you may wind up sweating excessively, thus increasing your fluid needs.

Women sweat less than men but may be at greater risk of a medical condition called “hyponatremia” (low blood salt level) if they participate in marathons or ultra-marathons and over hydrate with water during the race. Older individuals (65 years or older) may not hydrate sufficiently due to decreased perception of thirst, and young children have lower sweating rates.

WHICH BEVERAGE TO CHOOSE?
It is important to start drinking fluids several hours before exercise. Beverages with sodium or salted snacks may help retain fluids, an important consideration if you plan a long-endurance exercise bout, but water is the most important fluid for exercise of less than an hour’s duration.

Sport drinks with carbohydrates and electrolytes can be an important part of the hydration strategy and are helpful in sustaining exercise intensity in high-energy exercise lasting more than one hour.

Each individual has a unique fluid requirement, according to the American College of Sports Medicine. For marathon runners, this may range from 12-24 ounces of fluid per hour, with higher rates for faster, heavier runners competing in warm environments and lower rates for slower, smaller persons competing in cooler environments. After an activity, replace any fluid deficit promptly. Pre- and post-exercise body weights may help determine how much fluid is needed.

Sport drinks should not be part of a non-exercising person’s fluid needs, especially in children. Sport drinks have sugar and extra calories that may be contributing to the current obesity problem in our youth. Vitamin-waters or life waters have fewer calories than other sport drinks but some have increased sodium content that may contribute to high blood pressure. Alcohol is a diuretic and may lead to a dehydrated state (in addition to what it can do to your coordination).

Caffeine is in many beverages and foods and was previously thought to be a diuretic. The good news for all the bicyclists who hang out in the Grand County coffee shops is that moderate intake of caffeine does not appear to dehydrate an athlete as previously thought, and may actually improve endurance performance as well as mood. Caffeine may induce body fat mobilization and provide fatty acids for cell energy needs, sparing muscle glycogen (glucose) stores.

The bottom line is don’t ignore thirst! Drink to your health and to your athletic performance.

Dr. Gutgesell is a retired pediatrician and exercise physiologist from the University of Virginia and a Fellow of the ACSM. She can be seen bike riding or cross-country skiing near her Fraser home.


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• Raising the Roof: Meeting Jeff Johnston
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