The possible causes of dark brown urine after exercise are urine concentration, idiopathic hematuria, and urinary stones and other disease factors. 1. Concentrated urine: due to strenuous exercise, the body discharges too much sweat, so in comparison, the liquid metabolized by the kidneys is less, forming concentrated urine, resulting in the appearance of dark brown urine after exercise. 2. Idiopathic hematuria: Exercise may cause idiopathic hematuria, in which blood enters the urine, leading to a deeper color. 3. urinary stones: in addition to the above causes, some diseases can also cause hematuria resulting in dark brown urine, such as kidney stones, ureteral stones and other diseases, the friction between the stones and the local mucosal blood vessels in the body’s strenuous exercise will cause capillary rupture. To summarize, after exercise urine is dark brown more causes, need to be vigilant, if you feel uncomfortable, should promptly consult a doctor.