Basically it binds with oxygen to form oxymyoglobin. when muscles are excercising excessively oxymyoglobin splits and the oxygen is released into the blood to fuel the muscles by assisting in the production of ATP.

The main function of myoglobin is to carry oxygen to muscle tissues that have been damaged. Myoglobin is only found in a muscle injury.

These are all screening test, but not confirmation test. Red, cloudy urine means hematuria (blood in the urine) Red, clear urine means hemaglobinuria (hemaglobin in the urine. Dark reddish brown cola-colored urine means Myoglobinuria (myoglobin in the urine) Beer-brown-colored urine means indicative of bilirubin Dark red like port wine-colored urine means porphyrins (iron pigment). Very turbid urine means pyuria (Abnormal numbers of white blood cells in the urine) Orange Urine means the patient consume a lot of beta-carotene. Black to Dark brown urine means Alkaptonuria (melanin or homogentisic acid in the urine) Huge amount of urine means polyuria and may have type I/II diabetes High bilirubin levels in urine means hepatitis/jaundice High urobilinogen level in urine means excessive destruction of Red blood cells or patient have infectious mononucleosis. Low / No Urobilinogen and High Bilirubin in urine with high levels of bilirubin in the blood means Obstruction of Bile ducts/Obstructive jaundice Urine positive for Ketones means diabetic ketoacidosis, the patient is diabetic or having a crash diet. High glucose level in urine means lack of control of the diabetes High glucose level and normal blood sugar level means lowered renal threshold. Marked High Protein level in the urine means Nephrotic syndrome, Renal vein thrombosis, Amyloid disease, Lupus erythematosus. (4 gms/day) High protein level and heated at 100 C becomes normal/low protein level means multiple myeloma/macroglobulinemia. There are more informations if you bought the urinalysis book.