Glycogen is the stored energy in muscle, and it helps muscles retain water. This combination is critical for high intensity athletic performance. Depleting these energy stores is hardly something that will improve athletic performance. For a more details about the nutrient needs and the best fuel for endurance exercise, read Eating for Exercise.
Protein and Strength Athletes
While endurance athletes are easy to convince of the need for a high carbohydrate, low fat diet, strength athletes are a bit harder to convince of the need for adequate carbs and moderate protein. Strength athletes have long adhered to high protein diets in order to build muscle. This idea of high protein = more muscle is a bit overstated.
According to the research of sports nutritionists, strength athletes require high carbohydrate and adequate glycogen stored in the muscle. They point out that all high intensity, powerful muscle contractions (such as weight lifting) are fueled with carbohydrate. Neither fat nor protein can be oxidized rapidly enough to meet the demands of high-intensity exercise. Adequate dietary carbohydrate must be consumed on a daily basis to restore glycogen levels.
In fact, research shows that high protein/high fat diets can hurt performance. An inadequate amount of carbohydrate in the diet can result in:
- Reduced muscle glycogen stores in the muscle and liver
- Decreased endurance
- Decreased maximal effort
- Decreased serum glucose levels
- Increased risk of hypoglycemia
High protein/high fat diets can also have a negative overall impact on health, including the following:
- Increased risk of certain cancers
- Increased calcium excretion and increased risk of osteoporosis
- Reduced intake of vitamins, minerals, fiber and phytochemicals
But Don't Strength Athletes Need More Protein To Build Muscle?
Research hasn't shown this. In fact most strength athletes get far more protein than is necessary to promote muscle synthesis. The current protein recommendations for optimal muscle building in a strength athlete is 1.6 - 1.7 gm protein per kg of body weight. For a athlete weighing 90 kg (200 pounds) that is a total of 145 - 154 grams of protein a day [about 3 small chicken breasts]. There is no scientific evidence that more than 2.0 grams of protein per kg of body weight has any additional benefit in muscle strength or size.
How Much Protein is That?
Not much, as it turns out. Here is a list of some high protein foods.
Food, Amount, Protein
Fish, 3 oz, 21 grams
Chicken, 3 oz, 21 grams
Turkey, 3 oz, 21 grams
Meat, 3 oz, 21 grams
Milk, 8 oz, 8 grams
Tofu, 3 oz, 15 grams
Yogurt, 8 oz, 8 grams
Cheese, 3 oz, 21 grams
Peanut butter, 2 tbsp, 8 grams
Eggs, 2 large, 13 grams
So What Should an Athlete Eat?
The recommendations of sports nutritionists continues to show performance enhancing benefits.
These general guidelines are:
- 12-15% of daily calories from protein.
- 25-30% of daily calories from fat.
- 55-65% of daily calories from carbohydrate.
- An athlete's nutrition plan should be individualized to meet the needs of training and competition.
- Carbohydrates are the primary fuel for intense muscular efforts, and should be the cornerstone of an athlete's diet, regardless of the sport they play.
Source
Nutrition for Sport and Exercise, 2005, Jacqueline R. Berning, Suzanne Nelson Steen, ISBN 0763737755.
