The Power of Protein
Endurance athletes use protein for maintaining aerobic metabolism. When athletes don't get enough, the body takes protein from lean tissue, which gives overtrained endurance athletes a gaunt appearance. A protein deficit also slows recovery. The recommended dose is 1.2 to 1.4 g per kilogram of body weight/day of protein. For a 130-pound athlete, this means a total of 72 to 84 g protein a day.
-American Journal of Sports Medicine, March 1987; European Journal of Applied Physiology, 1996, vol. 74, no.5