Macronutrients in Sports Nutrition
For athletes engaged in serious physical activity, nutrition is crucial. It can improve endurance, speed recovery from exertion, lower the risk of injury and assist in rehabilitation. Most of the nutrients required for athletic performance fall into two main categories: macronutrients and micronutrients. Macronutrients are required in large quantities (grams/day) and include carbohydrates, proteins, fats and water.
Carbohydrates are the gold standard for athletic performance. They supply the brain and body with power and also produce stored glycogen. Complex carbs are the preferred fuel for muscles and the brain, and they should constitute the largest percentage of calories in the diet. Foods in this category include whole-grain breads, high-fiber cereals, pastas and rice, beans, fruits and vegetables.
Starch and glycogen are the body’s two most important carbohydrate energy contributors. Starch is available in plant foods, glycogen in animal foods. When starch is consumed, it digests slowly, releasing glucose steadily into the bloodstream. The glucose is stored in the liver and muscles in the form of glycogen until it is needed by the body. Generally speaking, athletes need 6-10 g of carbohydrates, per kg of body weight, per day.
180 pound male = 490-818 g carbohydrates per day
130 pound female = 354-590 g carbohydrates per day
Protein is an essential component of any diet. It builds, maintains and repairs cells and produces enzymes, hormones and antibodies. One prevailing myth among athletes is that eating a high protein diet can increase muscle size. In fact, muscularity is dictated primarily by training and genetics, not by diet.
High protein intake can compromise carbohydrate intake, which in turn can negatively affect the ability to train or compete at peak levels. Protein intakes above recommended levels can result in diuresis (increased urine formation and release) and dehydration, which may impair performance.
Protein supplies the body with building blocks, called amino acids, which are essential for the growth and repair of lean tissue. Of the 22 amino acids, 8 are essential (cannot be manufactured by the body) and must be obtained from food. Athletes should be sure to consume well-rounded, complete protein sources, which can be found in lean meats, skinless chicken, shellfish, soy, eggs, and low-fat milk products. Athletes require 1.2-2g/kg of body weight in protein per day (compared to 0.8g/kg for sedentary individuals).
Fat is vital for the production of key hormones and neurotransmitters in addition to cushioning the organs. However, the type and quantity of fat most consumed in the United States tends to be less than ideal. Diets high in bad fats (trans and saturated) are linked to many diseases, but certain fats—namely linoleic acid (n-6) and alpha-linolenic acid (n-3)—are essential for normal growth and health. It's important to emphasize healthy fats (n-6, n-3, polyunsaturated, monounsaturated) while trimming total fat intake.
Unsaturated fats, found in olive oil, nuts, avocados, canola oil and fish oil are healthy options to include in the daily diet, as well as sources of omega-3, like cod, salmon, trout, mackerel, leafy greens, walnuts, almonds and flaxseeds. Fat intake of 1g/kg of body weight per day is sufficient to meet dietary needs.
The nutrient consistently deficient for athletes is water. Sustaining the optimum level of hydration is vital for maintaining peak performance and achieving adequate recovery. Dehydration (defined as a fluid loss of more than 1 percent of body weight) can occur within 30 minutes of exercising. The American College of Sports Medicine has issued the following guidelines to help athletes stay hydrated:
2 hours before exercise: Drink 2 cups of fluid
During exercise: Drink 1/2-1 cup of fluid every 15 minutes
After exercise: Drink 2 cups of fluid for every pound lost during exercise
Sports drinks can assist in maintaining hydration when engaging in events lasting longer than one hour. A sports drink can keep blood sugar at a high level and spare muscle glycogen. Sports drinks should contain 6 percent carbohydrates, 50-100 kcals and 100 mg of sodium per 8 ounce serving. Remember that thirst is not an accurate indicator of hydration. The thirst mechanism kicks in only after you’ve lost 6 percent of your water weight, too late to prevent dehydration.
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