Sorry it has taken so long to get back.
I would like to begin my first answer-post by starting from ground zero and define a protein.

Protein - A macromolecule that is composed of essential and non-essential amino acids. The non-essential are made by the body and the essential must be obtained through food. Proteins are not only found in muscles but hormones, cell receptors, enzymes, and come in all shapes and sizes.



Walker represents a small percentage of athletes. He is an amazing machine who has smoked me on the trails since I can remember and I can't imagine his average speed on the road. He breaks down muscle everyday as he trains or 'overtrains', which can cause an injury, but has not occurred. I believe the reason he remains healthy is his regiment is on the threshold of his optimum level (exercise vs protein intake) allows daily training and continued growth.

Extra protein has been a topic for years in the athletic community. As one, would predict; "I want more muscle, so I must work out and eat more protein to build it". Bodybuilders and endurance athletes (like Walker) are completely different when it comes to their energy source, which affects how proteins are utilized. Bodybuilders use glucose as their main energy source because of its short intensity and doesn't allow fat or protein to be used. Their protein is used to supplement tissue and muscle rebuilding. Endurance athletes sustain activity for 2-5 hours and use protein for 5-10% of their energy. Just as muscles need replenishing so does the source of energy used. So, endurance athletes usually need more protein in their diet than bodybuilders.

Consuming too much protein is thought to cause damage to your kidneys because of the hard work put into eliminating nitrogenous waste produced from protein breakdown. This was made clear by a study by Zaragoza et al (1987) in which animals were fed very high protein diets for more than half their life span and saw no adverse effects. The only negative aspect of over consumption of protein is it can lead to excess calories that are not burned and stored as fat, and protein is an inefficient source of energy for the body to use.
The recommended daily amount of protein is listed below.

RDA for sedentary adult 0.4
Adult recreational exerciser 0.5-0.75
Adult competitive athlete 0.6-0.9
Adult building muscle mass 0.7-0.9
Dieting athlete 0.7-1.0
Growing teenage athlete 0.9-1.0
*To find your daily protein requirement, multiply the appropriate numbers in this table by your weight in pounds.

I hope you have enjoyed the first session of my neuronal activity. Please feel free to correct me or suggest what ever you like.