A pigmented material contained in muscle cells, which serves as oxygen reservoir of the muscular fiber.

Increased level of Myoglobin in blood may indicate damage to the Myocardium (heart muscle), as encountered in a heart attack and thus be helpful in the diagnosis of myocardial infarction.

However, it must be stated that increased Myoglobin level in blood is an unspecific finding and can occur in various conditions, other than Myocardial Infarction, because any muscular damage can increase its blood level.