If you exercise, you need to replenish the fluids your body loses in sweating. For the real go-getters, that could be a problem. If you weigh about 150 pounds and sweat away more than two percent of body weight or three pounds, you are putting your heart under stress. When the body is under stress, your temperature increases and performance declines. If you are an athlete or someone who takes exercise seriously, fluid replacement is critical.
Dehydration severely limits athletic performance.
Heat stroke, organ damage and possible death may result if fluids are not consumed at regular intervals during exercise. The best way to avoid dehydration is to drink enough fluids to offset fluid loss. Drink before, during and after a workout. The serious exerciser can weigh before and after a typical workout to figure out how much fluid is needed. Consume two cups of water for each pound lost during exercise.