Sports nutrition for young athletes
Proper nutrition is vital for child and adolescent athletes to attain proper growth and perform optimally in sports. Young athletes need to learn what foods are good for energy, when to eat certain foods, how to eat during an event, and when and what to eat to replenish after activity. A well-balanced diet containing appropriate amounts of macronutrients (protein, carbohydrates and fat) and micronutrients (vitamins and minerals) is essential to provide enough energy for growth and activity. Fluids are also essential for hydration to support growth and athletic performance.
Recommended energy requirements, Kcal/day:
Male
Age, years
4–6years of age - 1800
7–10years of age - 2000
11–14years of age - 2500
15–18years of age - 3000
Female
4–6years of age - 1800
7–10years of age - 2000
11–14years of age - 2200
15–18years of age - 2200
Macronutrients = carbohydrates, protein and fats; provide the fuel for physical activity and sports participation.
Carbohydrates
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The most important fuel source for athletes because they provide the glucose used for energy.
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1 gram of carbohydrate contains approximately 4 kilocalories of energy.
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Glucose is stored as glycogen in muscles and liver.
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Muscle glycogen is the most readily available energy source for working muscle and can be released more quickly than other energy sources.
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Carbohydrates should comprise 45% to 65% of total caloric intake for 4 to 18 year-olds.
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Good sources of carbohydrates include whole grains, vegetables, fruits, milk and yogurt.
Proteins
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Build and repair muscle, hair, nails and skin.
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For mild exercise and exercise of short duration, proteins do not act as a primary source of energy.
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However, as exercise duration increases, proteins help to maintain blood glucose through liver gluconeogenesis (the generation of glucose from non-carbohydrate precursors).
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1 gram of protein provides 4 kilocalories of energy.
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Protein should comprise approximately 10% to 30% of total energy intake for 4 to 18 year-olds.
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Good sources of protein include lean meat and poultry, fish, eggs, dairy products, beans and nuts, including peanuts.
Fat
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Necessary to absorb fat-soluble vitamins (A, D, E, K), to provide essential fatty acids, protect vital organs and provide insulation.
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Fat also provides the feeling of satiety (fullness).
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It is a calorie-dense source of energy (1 gram provides 9 kilocalories) but is more difficult to use.
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Fats should comprise 25% to 35% of total energy intake for 4 to 18 year-olds.
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Saturated fats should comprise no more than 10% of total energy intake.
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Good sources of fat include lean meat and poultry, fish, nuts, seeds, dairy products, and olive and canola oils.
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Fat from chips, candy, fried foods and baked goods should be minimized.
Micronutrients = vitamins and minerals
Particular attention should be devoted to ensuring that athletes consume proper amounts of calcium, vitamin D and iron.
Calcium
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Important for bone health, normal enzyme activity and muscle contraction.
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The daily recommended intake (DRI) of calcium is 1000 mg/day for 4 to 8 year-olds and 1300 mg/day for 9 to 18 year-olds.
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Calcium is contained in a variety of foods and beverages, including milk, yogurt, cheese, broccoli, spinach and fortified grain products.
Vitamin D
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Necessary for bone health and is involved in the absorption and regulation of calcium.
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Current recommendations suggest 600 IU/day for 4 to 18 year-olds.
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Normal values of vitamin D also vary depending on geographical location and race.
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Athletes living in northern latitudes or who train indoors (eg, figure skaters, gymnasts, dancers) are more likely to be vitamin D deficient.
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Sources of vitamin D include fortified foods, such as milk, and sun exposure.
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Dairy products other than milk, such as yogurt, do not contain vitamin D.
Iron
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Important for oxygen delivery to body tissues.
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During adolescence, more iron is required to support growth as well as increases in blood volume and lean muscle mass.
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Boys and girls 9 to 13 years of age should ingest 8 mg/day to avoid depletion of iron stores and iron-deficiency anemia.
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Adolescents 14 to 18 years of age require more iron, up to 11 mg/day for males and 15 mg/day for females.
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Iron depletion is common in athletes because of diets poor in meat, fish and poultry, or increased iron losses in urine, feces, sweat or menstrual blood.
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Therefore, athletes, particularly female athletes, vegetarians and distance runners should be screened periodically for iron status.
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Iron-rich foods include eggs, leafy green vegetables, fortified whole grains and lean meat.
Fluids
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Proper hydration requires fluid intake before, during and after exercise or activity.
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Before activity, athletes should consume 400 mL to 600 mL of cold water 2 h to 3 h before their event.
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During sporting activities, athletes should consume 150 mL to 300 mL of fluid every 15 min to 20 min.
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For events lasting less than 1 h, water is sufficient.
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For events lasting longer than 60 min and/or taking place in hot, humid weather, sports drinks containing 6% carbohydrates and 20 mEq/L to 30 mEq/L of sodium chloride are recommended to replace energy stores and fluid/electrolyte losses.
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Following activity, athletes should drink enough fluid to replace sweat losses, usually approximately 1.5 L of fluid/kg of body weight lost.
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The consumption of sodium-containing fluids and snacks after exercise helps with rehydration by stimulating thirst and fluid retention.
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For non-athletes, routine ingestion of carbohydrate-containing sports drinks can result in consumption of excessive calories, increasing the risks of overweight and obesity, as well as dental caries and, therefore, should be avoided.
Recovery foods
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Should be consumed within 30 min of exercise, and again within 1 h to 2 h of exercise, to help reload muscles with glycogen and allow for proper recovery.
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These foods should include protein and carbohydrates.
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Examples include graham crackers with peanut butter and juice, yogurt with fruit, or a sports drink with fruit and cheese.
Meals
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It is important for athletes to discover which foods they like that also help to maximize performance.
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Athletes should not experiment with new foods or new routines on the day of competition.
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Meals should be a minimum of 3 h before an event to allow for proper digestion and to minimize incidence of gastrointestinal upset during exercise.
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Meals should include carbohydrates, protein and fat.
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Fibre should be limited.
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High-fat meals should be avoided before exercise because they can delay gastric-emptying, make athletes feel sluggish and thereby adversely affect performance.
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For early morning practices or events, having a snack or liquid meal 1 h to 2 h before exercise, followed by a full breakfast after the event, will help ensure sufficient energy to maximize performance.
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Pre-game snacks or liquid meals should be ingested 1 h to 2 h before an event to allow for digestion before start of exercise.
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Snacks can include fresh fruit, dried fruit, a bowl of cereal with milk, juice or fruit-based smoothies. During an event, sports drinks, fruit or granola bars can be ingested to help refuel and keep energy levels high.
References:
Canadian Pediatric Society
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