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Energy Demands
An athlete should consume enough calories to offset energy expenditure. Athletes involved in intense exercise may expend 600-1200 kcal/hour or more during exercise. For this reason their calorie needs may approach 50-80 kcal/kg/day that is 2500 – 8000kcal/day for a 50-100kg athletes.
Very often it is difficult for larger athletes or those engaged in intense exercise, to be able to eat enough food to meet calorie needs. Eating a diet deficient in calories leads to significant weight loss, illness, onset of physical and psychological symptoms of overtraining and reduction in performance. Therefore it is essential to eat sufficiently to off set increased energy demands of training and maintain body weight.
This sounds simple but intense training often suppresses appetite. Some athletes do not like to exercise within several hours after eating because of sensations of fullness or gastro intestinal distress.
Athletes involved in moderate and high volume training need greater amounts of carbohydrates and protein in their diet to meet macronutrient needs.
Carbohydrates
Carbohydrates serve as the primary fuel for high intensity exercise. Carbohydrate is stored in the muscle (15g/kg) and liver (80-100g). Intense exercise depletes muscle and liver glycogen stores which are replenished from dietary carbohydrates. However when significant amounts of carbohydrates are depleted, it may be difficult to fully replenish it within one day. So when the athlete trainees continuously, the carbohydrate levels decline leading to fatigue and poor performance.
Athletes involved in intense training of 2-3 hours per day typically need to consume a diet containing 55-65% carbohydrate i.e. 5-8g/kg/day to maintain liver and muscle glycogen. Preferably the majority of dietary carbohydrate should be complex carbohydrates with low to moderate glycemic index. However since it is difficult to consume this amount of carbohydrate, concentrated juices, drinks or high carbohydrate supplements are suggested.
Healthy sources: Whole grain cereals, breads, and Rotis, fruits, vegetables and variety of beans.
Nutritional benefits : Major source of energy, vitamins, minerals, and fiber.
Health benefits : Regularity; healthier blood cholesterol levels; and lower risk of heart disease, diabetes, and cancer.
Performance benefit : Carbs are your major muscle fuel source for high-intensity exercise.
Protein
Athletes engaged in intense training need to ingest 1.5-2.0g/kg/day of protein to maintain protein balance. If this requirement is not met, the athlete will be in negative nitrogen balance and over a period this may lead to lean muscle wasting and training intolerance. High quality protein should be given. Proteins in supplements are whey, casein, soy and egg protein which are well assimilated.
Fat
It is recommended that athletes consume a moderate amount of fat. If the training is high volume training, 50% of calories may be obtained from fats.
Healthy sources Vegetable oils such as safflower/sunflower oil and olive oil, nuts, seeds, and fish.
Nutritional benefits Major source of energy; vitamins A, D, E, K; omega-3 fatty acids; and other essential fats.
Health benefits Healthier blood cholesterol levels and lower risk of heart disease.
Performance benefits Fats are the major muscle fuel sources for low-intensity exercise.
Vitamins
- Specific vitamins may possess some benefits. Some vitamins may help athletes to tolerate training to a better degree by reducing oxidative damage (Vit E and C) and help maintain healthy immune system during training.
- It is recommended that athletes consume a low dose multivitamin.
Minerals
- Some minerals have been found to be deficient in athletes or become deficient in response to training. When mineral status is in adequate, exercise capacity is reduces.
- Calcium supplementation helps to maintain bone mass and prevent osteoporosis.
- Iron supplementation also improves exercise capacity.
- Increasing salt availability during training in the heat helps in maintaining fluid balance and preventing dehydration.
- Zinc supplementation decreases exercise induced changes in immune function.
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Participants