Visitors might experience heavy breathing, rapid heartbeat, fatigue, headache, nausea or insomnia. This is normal. In Aspen, each breath takes in only 70 to 80 percent of the oxygen available at sea level. You can minimize the effects of high altitude by drinking lots of water, avoiding alcohol, eating light, high-carbohydrate meals, increasing physical activity gradually, and rest when tired. After about four or five days, most visitors begin to feel better.
Water loss occurs rapidly when excercising at high altitude.
Low humidity and direct sun cause perspiration, a potent combination. While exercising, the movement of air over your body is accelerating water loss from skin. If you are thirsty, dehydration has already begun. Drink water or sports drinks before, during and after exercising. Try to consume no less than a pint of liquid per hour while excercising.