an athlete, a tough workout demands the manufacture of new proteins to replace damaged ones and to replenish thousands of red blood cells (Applegate, 1996). A protein only lives for a finite amount of time and then it breaks down into its constituent amino acids. These recombine to make new proteins, and each day a person needs to replace almost two thirds of a pound of body protein.
A person needs to take in around 25 percent of the total protein they need to manufacture each day. This means taking in roughly 15 percent of total calorie intake as protein: that is 50 to 100 grams. If protein intake is consistently less than this, the body's store of protein will diminish and health will suffer. Respiratory infections, injuries that don't heal in a timely manner, and even hair loss or splitting and breaking of fingernails are all signs of insufficient protein in the body (Applegate, 1996).
Any kind of habitual exercise boosts protein needs. Runners and other athletes need more. This is especially true if glycogen stores run low, which often happens during a long workout or race, or if a person cuts back on calories to lose weight. According to Applegate (1996), this causes certain amino acids to bypass their normal recycling route and instead become fuel for the muscles, and boosts protein intake requirements to 25 percent or more.
Muscle damage caused by a tough workout or race also increases protein needs. New proteins are necessary to repair small tears in muscle fibers, she adds, and with strength training, protein intake needs to be increased even more to support increased muscle bulk. Applegate recommends that runners take in between 0.50 and 0.72 grams per pound of body weight, depending on individual metabolism and energy expenditure. This means a 150-pound runner should get about 90 grams a day. Most well-fed athletes get at least this amount.
The body manufactures all but nine of the 20 amino ...