Nutrition and Exercise: Eating to Fuel Your Workouts
Carbohydrates are an important nutrient for athletes because they maintain blood glucose levels during exercise and replace muscle glycogen, the carbohydrate that is stored inside muscles. Muscle glycogen is the main fuel during prolonged exercise.
To stay fueled, carbohydrate recommendations for athletes exercising on a regular, highly-intensive basis range from 6 to 10 grams/kg body. The amount required depends on an individual’s total daily calorie expenditure, type of exercise, gender, and environmental conditions (i.e. heat, cold, or high altitude). For part-time recreational exercisers, the diet should be comprised of about 50% carbohydrates coming from healthy sources like whole grains and not refined carbohydrates.
Protein recommendations for endurance and strength-trained athletes range from 1.2 to 1.7 grams/kg body weight. This protein intake can generally be met through diet alone, without the use of protein or amino acid supplements.
Fat intake should range from 20% to 30% of total calorie intake. Fat shouldn’t be restricted below 20% because fat is an important source of calories, fat-soluble vitamins A, D, E and K, and essential fatty acids.
Adequate fluid intake before, during, and after exercise is important for health and optimal performance. Two to three hours before exercise, drink 15-20 ounces or water, and then another 8-10 ounces ten to fifteen minutes before exercise. During exercise, drink 8-10 ounces every ten to fifteen minutes.
For intense endurance exercise lasting more than 90 minutes or when you are exercising in an extreme environment (heat, cold, or high altitude), the goal is to drink to stay hydrated and to provide carbohydrate so that blood glucose levels are maintained. Intake should provide 30-60 grams of carbohydrate per hour. This carbohydrate can be consumed in a 6-8% carbohydrate sports beverage (8-16 ounces) every ten to fifteen minutes.
Before You Exercise
Food eaten before exercise should be relatively low in fat and fiber, moderate in protein and relatively high in carbohydrate to maximize maintenance of blood glucose.
Within 30 minutes after exercise, dietary goals are to provide adequate fluids, electrolytes, calories, protein and carbohydrates to replace muscle glycogen and promote recovery. A carbohydrate intake of approximately 0.5-0.7 grams per pound during the first thirty minutes and again every two hours for four to six hours will be sufficient to replace glycogen stores. Protein consumed after exercise will provide amino acids for building and repair of muscle tissue. So adding protein 0.2 g – 0.5 g/kg/day to carbohydrate at a ratio of 3 – 4:1 (Carbohydrate: Protein) may further improve glycogen re-synthesis so properly refuel for future exercise.
Maria Faires, RD