Under special circumstances, fluid intake and output should be more carefully monitored. Examples of the special circumstances follow:
Infants, young children and the elderly
- Children have lower sweating capacity than adults.
- They tolerate high temperature less efficiently.
- Frequent vomiting and severe diarrhea in infants and young children quickly can lead to water dehydration.
- The Elderly may be at increased risk for dehydration because their thirst mechanism may not be as efficient as at younger ages.
- The influence of medications and the presence of disease are other factors that affect fluid intake and water balance.
Important: For both the young and the old, encourage water intake often.
- Of all nutritional concerns for athletes, the most critical is adequate water intake.
- The athlete's immediate need for water is to control body temperature and to cool working muscles.
- Lack of water, above all other nutrients, has the ability to hinder performance and lead to serious complications.
- For example, fluid loss of two to three percent of body weight by sweating impairs performance.
- Fluid losses of seven to 10 percent of body weight result in heat stroke and death.
- Two to three percent fluid loss in a 150 pound (68 kg.) individual represents three (1.4 kg.) to four and a half pounds (2 kg.) of body weight or one and a half to two quarts lost water.
- Marathon runners and other long distance athletes may lose up to three quarts (or six pounds – 2.7 kg.) of sweat per hour.
- To prevent dehydration during exercise, athletes should drink fluids before, during and after activity. Even exercise in cold weather results in sweat production and requires adequate fluid replacement.
- Although electrolytes such as sodium also are lost through perspiration, the immediate need is for water alone. In most circumstances sodium and other electrolytes can be replaced after exercise. Seasonings (especially salt) on foods at regular meals usually will do the trick.
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