Maintaining proper fluid levels is extremely important during exercise. Some research indicates that
you should drink 50 percent more than it takes to satisfy your thirst. If you exercise without fluids, especially in the heat, the stroke volume -- the volume of blood pushed out with each heartbeat -- decline. This results in a decrease in cardiac output, which is the amount of blood pumped by the heart.
Your heart rate will then drift upwards, oxygen uptake will increase and body temperature will go up. Therefore, it is most important to keep well hydrated to prevent injury to your heart's function.
Since most of our body weight is water, it is still one of the best fluid replacements. If you don't drink enough, your heart and the rest of your body will not get enough blood and oxygen. At least one hour
prior to your exercise workout, you should drink 8-10 ounces of water and continue to drink the same if
you plan to exercise for more than an hour, then every 20-30 minutes with continued exercise.
Try to avoid exercising during the warmest hours of the day. Wear a hat and light-weight, loose-fitting
clothing, take frequent cool showers or baths and stay in air conditioning as often as possible to help
lower the body temperature. If you feel uncomfortable, put wet towels on your body, look for a cooler
location and get out of the sun. An estimated 1,000 Americans die each year from heat-related illnesses
that could be prevented by controlling your body temperature.
And remember the magic fluid: water.
Dr. Robert F. Weiss, a Sport Podiatrist, was a member of the Medical Advisory Committee of the 1984 & 1988 Olympic Marathon Trials.