Fitness and Fluids
As a person exercises, the internal body temperature rises. That triggers the body to release internal fluid to the outside through millions of sweat glands and via heightened respiration. As the high temperature sweat evaporates off the skin, it takes heat with it, cooling the body down again.
That internal temperature regulatory system is vital to health, but losing too much fluid can also produce problems. High activity can cause a person to lose three quarts or more of fluid per hour. As the amount of fluid lost increases, performance decreases.
Excessive fluid loss strains the cardiovascular system as well, which can lead to dizziness, muscle cramps and even heat stroke, in extreme cases.
Professional guidelines recommend regular replacement of both water and electrolytes (sodium, potassium and others) by drinking a sports drink before, during and after a workout. The right amount will vary with body weight and type, tendency to sweat, external temperature and other variables, but here are some rough figures.
Drink about 18oz (0.53 liter) a couple of hours before beginning your workout, then another 10oz (0.3 liter) about 15 minutes before starting your warm-up. Drink at least 30oz (0.89 liter) every hour you work out, then - after a cool-down period of a few minutes - another 20oz (0.59 liter) after the workout.
Caffeine-containing drinks should be avoided when re-hydrating since they have a diuretic effect. Consuming alcohol, too, is a bad idea for at least a couple of hours after a strenuous workout. Apart from the high amount of calories most alcoholic drinks contain, the alcohol can disrupt the smooth rate of cool-down as the body temperature changes.
Beware of sports drinks that have high amounts of sugar. You don't want to put back all those calories you worked hard to burn, and too much sugar can unbalance cardiovascular regulation after vigorous exercise. That means, go easy on both soft drinks and concentrated fruit juices. Even diet soft drinks have excessive carbon dioxide, which is less than ideal for best recovery.
Look for drinks that replace magnesium (~100 mg per liter), as well as sodium and potassium. Both sodium and potassium are essential elements for proper heart function. They help regulate cellular electrical activity.
Isotonic drinks are designed to closely match the body's natural concentrations of needed minerals, vitamins and enzymes. That makes them easier to absorb and excellent replacement fluids.
Maintain overall health, avoid medical problems and maintain peak performance by proper fluid regulation.