e-How gives a good breakdown for this kind of forum:
Rhabdomyolysis is the name given to the breakdown of muscle fibers, which results in the release of myoglobin into the bloodstream that can be harmful to organ systems. Prolonged, strenuous exercise is a leading cause of rhabdomyolysis.
Significance
While rhabdomyolysis is not a normal risk associated with exercise, it can be brought on by severe exertion, such as marathon running or unusual amounts of high-impact calisthenics.
Explanation
When exercise continues long enough for the body to become depleted of oxygen and fat needed to continue producing energy, the body may begin to break down muscle fibers to use in place of fat. This causes the release of the protein myoglobin, which, when further broken down, contains compounds that can harm the body.
Read more: Exercise-Induced Rhabdomyolysis | eHow.com
http://www.ehow.com/facts_5101692_exerc ... z1CGJOaeph