Why is protein important for athletes?

Protein is essential to the human body for growth and repair of tissue. Beyond making muscle, protein helps athletes to maintain blood, to keep hormones working and to fight off disease by enriching the immune system. Protein is made up of chains of amino acids, some of which the body cannot manufacture. Athletes who get too little protein may find that their hair falls out easily, and females may develop amenorrhea. Some athletes surprisingly get too little protein; perhaps they are vegetarian, perhaps they focus only on increasing carbohydrates as fuel or perhaps they cannot find the time or energy to create balanced meals with protein. A high-carbohydrate diet that is low in protein can still cause fatigue and poor performance. Other athletes may overdo protein intake at the expense of a balanced diet, or rely on amino acid supplements of questionable value to increase protein intake that basic diet improvements could provide.

How much protein should an athlete consume?

The normal amount of protein recommended for sedentary people is 0.8 grams of protein per kilogram of body weight per day. (Take your weight in pounds and divide by 2.2 to get your weight in kilograms.) In athletes, several factors determine the amount of protein needed -- duration and intensity of exercise, degree of training and current energy and protein intake of the diet.

Athletes who train hard need more protein than the average individual. In one study, men who did aerobic exercise regularly (biking, running, swimming) needed additional protein 50 percent over their RDA. By measuring nitrogen balance, a technique used to determine if more protein is lost from the body than taken in by the diet, researchers found these active men needed extra protein to cover the cost of exercise. The additional amount was about 27 grams, the same as a 3-ounce chicken breast, two and a half cups of milk or a can of tuna. This makes it unnecessary to purchase expensive amino acid drinks. The amount of amino acids in pills and drinks should be compared to what 1 ounce of meat, fish or chicken provides. An ounce of food protein provides 7 grams of protein, or 7000 milligrams of amino acids.

The explanation for this increased protein comes from studies showing that amino acids are also broken down for energy in exercising muscles. When glycogen stores get low during an exercise session, the body breaks down some fat and a little bit of muscle. During post-exercise recovery, rebuilding with protein is necessary.

Strength athletes need 1.4 to 1.8 grams of protein per kilogram of body weight per day; this extra protein goes to increase muscle weight. Runners and other endurance athletes also need more protein because on long workouts their muscles burn some protein. These athletes need 1.2 to 1.4 grams of protein per kilogram of body weight per day. Because endurance athletes weigh less than strength trainers, the amount of protein needed per day is less. For example, a 200-pound bodybuilder (91 kilograms) needs 127 to 163 grams of protein; on the other hand, a 150-pound runner (68 kilograms) may need 82 to 95 grams of protein. The protein goal is about 12 to 20 percent of total calorie intake. Moderate exercisers need additional 10 percent protein above the RDA, and athletes in training may need 25 to 50 percent more than the RDA.

Protein is required on a daily basis, but too much can be a problem. Extra calories, no matter what the source, can be converted to stored body fat and protein beyond the recommendations must be processed by the kidneys and liver to rid the body of unwanted nitrogen byproducts. The kidneys have to flush out toxins in urine, so athletes getting an excess of protein could risk dehydration. Also, studies show that excessive protein may cause the loss of calcium in urine, which puts women at risk for osteoporosis.