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C h a p t e r 9
Eating for Health and Performance
An adequate calcium intake is important not only to prevent osteoporosis (bone
deterioration), but because calcium also helps to maintain bone density and prevent
stress fractures. An athlete’s calcium needs are greatest during adolescence, when the
bones are growing. Young women athletes who develop amenorrhea (absence of menses)
have increased bone loss. This is a serious health risk, since once bone mass is
lost, it may never be fully replaced.
The AI values for calcium are 1,300 milligrams for youths and adolescents ages 9 to
18. If an athlete does not consume four servings of calcium rich foods such as milk,
cheese, yogurt, or green leafy vegetables each day, a calcium supplement may be
necessary. One glass of milk contains 300 milligrams of calcium. Table 5 lists good
sources of calcium and the milligrams of calcium each provides.
WATER
Water is the most essential of all nutrients for athletes. At rest, athletes need at least
two quarts of fluid daily. An adequate supply of water is necessary for control of body
temperature during exercise, for energy production, and for elimination of waste
products from metabolism. Dehydration – the loss of body water – impairs exercise
performance and increases the risk of heat injury.
Consuming adequate fluid before, during and after exercise is vital for safeguarding
health and optimizing athletic performance. Athletes should drink 14 to 22 ounces
of fluid two to three hours before exercise. During exercise, athletes should drink
6 to 12 ounces of fluid every 15 to 20 minutes. Fluid intake should closely match
the fluid loss from sweating to avoid the detrimental effects of dehydration. After
exercise, athletes should drink at least 16 to 24 ounces of fluid to replace every
pound of body weight lost during exercise.
Thirst is not an adequate guide to fluid replacement. Most athletes replace only
50 percent of their fluid losses during exercise. Encourage athletes to replace fluids by
drinking according to a time schedule rather than in response to thirst.
Sports drinks containing carbohydrate and sodium are recommended during
intense exercise lasting longer than an hour. The carbohydrate helps to delay fatigue,
improve fluid absorption and replace glycogen following exercise. The sodium helps
to stimulate thirst, increase voluntary fluid intake and enhance fluid retention.
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