than 10% from saturated fat. Research does not show any beneficial effects from a diet that includes
excessive fat intake (>70% of total energy).
Vitamin and Mineral Requirements
Micronutrients function in a variety of roles that optimize health. They are involved in energy
production, blood synthesis, maintenance of bone health, immune function, and the prevention of
oxidative damage. They also aid in the process of muscle and tissue repair during recovery from
exercise or injury.
Generally, athletes consuming a healthy diet do not require any additional supplementation of
micronutrients. However, a multivitamin supplement may be appropriate if an athlete is dieting, or
avoids certain food or food groups. Supplementation of single nutrients such as iron may be required
if a deficiency is diagnosed by a medical professional.
While supplementation with high doses of antioxidants (Vitamins C, E and B-carotene) is becoming a
popular practice among athletes, there is little evidence to suggest that antioxidant supplements
enhance performance. Athletes should be cautious of mega-dosing with these vitamins since higher
doses are likely to promote a deleterious effect.
Vegetarian athletes may be at risk for low intakes of iron, calcium, vitamin D, riboflavin, zinc and
vitamin B
12.
Consultation with a sports dietitian is recommended to ensure adequate intakes of these
nutrients.
Timing of Food and Fluid Intakes
Before Exercise
The pre-exercise meal or snack should be familiar to the athlete and contain small amounts of fat and
fiber in order to promote quick digestion and minimize potential gastrointestinal discomfort. The meal
should be high in carbohydrates and moderate in protein. The amount of carbohydrate shown to
enhance performance generally ranges from 200-300 grams of carbohydrate eaten 3-4 hours before
an event.
Fluid should be consumed at least 4 hours before an exercise event. A water or sport beverage is
appropriate. The athlete should aim for 5-7 mL/kg (2-3 mL/lb) body weight of fluid for optimal
performance. Hyperhydration with water and glycerol mixtures should be discouraged since no
performance benefit has been established by this practice.
During Exercise
Sports drinks containing 6-8% carbohydrates are beneficial for exercise lasting longer than 1 hour in
duration. For long workouts or events, athletes are advised to consume 0.7g carbohydrates/kg body
weight (approximately 30-60 grams/hour.) Research has demonstrated an extended endurance
performance from this practice. Sports drinks offer a significant benefit for athletes who exercise in
the morning after an overnight fast when liver glycogen levels are low. Supplementing carbohydrates
during this type of exercise will also benefit athletes who have not eaten a pre-exercise meal as well
as those who are restricting calories for weight loss.
The greatest improvements in performance have been observed when sports drinks are used for
hydration at 15-20 min intervals. Liquid mixtures of glucose, fructose or other simple sugars are
equally effective. However, fructose alone is not as effective and may cause diarrhea.