Out of the many protein sources out there, whey protein is the ultimate. It comes from milk. During the process of turning milk into cheese, whey protein is separated out. Protein can be found in a variety of foods - mainly meat...

During this process the cells make ATP (adenosine triphosphate), which provides energy for most of the chemical reactions in the body. Lactic acid formation doesn't use oxygen, so the process is often called anaerobic metabolism...