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Thursday, 20 January 2011

Sports Nutrition



Eating a balanced diet is key to sports nutrition. Sports nutrition is different from normal nutrition because the athlete requires more amounts of macro and micro nutrients in order to perform well. Fluids are also important as athletes lose a lot of fluids, and dehydration is common. Because of their heavy training and strenuous activities the right nutrition should be provided.

Energy: Energy requirements vary with weight, height, age, sex and metabolic rate with the type, intensity, frequency and duration of training and performance. Persons who exercise 30 to 40 minutes per day, three times a week and the nutritional needs they can meet are 25 to 35 kcals/day. An athlete weighing 50 kg doing intense training of 2 to 3hours per day five to six times a week spends 600 to 1200 kcals energy a day. Thus the energy requirements are increased to 50 to 80 kcal/day. For heavier athletes calories needs can be increased to 100 to 150kcals/day.

Carbohydrates: The amount of carbohydrates required by the athletes depends on the total daily energy expenditure, type of training and sports, environment etc. Carbohydrate intake ranges from 5 to 7g/kg /day. Increased needs can demand to 7 to 10g/kg/day. Commercial sports drinks providing easily digested high carbohydrate fluids are popular with athletes. Foods high in fat, fiber and lactose should be avoided as they may cause gastrointestinal distress. Appropriate pregame meals are bagel with jam or jelly, dry cereal, baked potato, spaghetti, fruit smoothie prepared with a protein powder.
          
Protein:  The average adult requires 0.8 to 1gm/kg/day of protein. Athletes need protein to rebuild muscle and for tissue repair. Protein intake also allows for proper utilization of carbohydrates for energy. Strength training athletes actually require high amounts of carbohydrates than fats or proteins. As proteins cannot be oxidized rapidly enough to meet the demands of high intensity exercises. Strength training athletes need 1.4 to 1.8 g/kg/day. Endurance athletes need 1.2 to 1.4 g/kg/day. The main sources of proteins are meat, eggs, milk, soy, beans.

Fat: Fat also provides energy; 1 gm of fat provides 9 kcals. This is almost double to energy provided by carbohydrates and proteins. Apart from providing calories it also supplies essential fatty acids that are necessary for skin, hormones and transport of fat soluble vitamins. Fat is a valuable metabolic fuel for muscle activity. Athletes should consume 20 to 30% of their calories from fat.

Vitamins: Vitamins and minerals in exercise have an important role. Deficiencies of vitamins are supplemented in the diet. If athlete meets requirements for increased energy, the vitamin and mineral requirements also be met. In exercise metabolism is increased and this increased needs demand for B vitamins. B vitamins should be supplemented for some athletes such as rowers, wrestlers who consume low calorie diets. If a athlete is a vegetarian then deficiency of vitamin B12 may occur so it should be supplemented. Folic acid should also be supplied through diet , and eat foods rich in folic acid such as fortified foods, whole grains , fruits and vegetables. Vitamin C and E acts as antioxidants and have protective effect against exercise induced oxidative injury and the acute immune response changes the exercise produces.

Minerals: Iron has one of the most critical implications for sports performance. Iron deficiency anemia limits aerobic endurance and the capacity for work. The factors which affects the low iron levels are poor diet, calorie restricted diet, a female athlete with heavy menstrual losses. All athletes should be screened on regular basis of their hemoglobin levels. Heavy training also causes decrease in serum ferritin and hemoglobin specially in conditioning phase known as sports anemia. Especially for female athletes osteoporosis is common this is due to calcium deficiency. Diet should be modified and should include calcium rich foods. Also vitamin D should be in proper. Calcium foods such as calcium fortified milk, soy milk tofu, ragi are all good sources.

Fluids: Fluid balance should be maintained properly. Because exercise produces heat regular fluid intake is essential for maintaining a body temperature that maximizes. Approximately 20% of water comes from water found in foods. Remaining 80% comes from plain water, juice, milk, tea, soup etc.  Fluid intake should be adequate. Drinking after, before and during any kind of sports activity is to prevent overheating and dehydration. There are many sports drinks available to keep healthy and active.

Supplements: Amino acids and immune boosters like glutamine can be provided. Supplements such as high energy drinks, Nutrition bars, high protein powder diets and immune booster powders can be given. Muscle consists of 60% of pool as glutamine and to build muscle athletes need glutamine and it also acts as immune booster.

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