Myoglobin is a protein found in heart tissue and other muscles. It helps trap oxygen in the muscle cells so that the muscles can work properly.
Strenuous exercise, an injury to a muscle, or a shot into the muscle can cause myoglobin levels to go up. High levels can also be caused by heavy alcohol use. Myoglobin levels also are high in people who have kidney failure, because myoglobin is removed from the blood by the kidneys.
WebMD Medical Reference from Healthwise