The redness of urine after strenuous exercise is a condition of hematuria after exercise, which is caused by physiological erythrocyte exudation, urine concentration, stones, menstruation, gynecological inflammation and other reasons. 1. Physiological erythrocyte exudation: after strenuous exercise, the reflux condition will be abnormal, and accompanied by an increase in glomerular permeability, resulting in the exudation of erythrocytes, resulting in a slight hematuria. 2. Concentration of urine: after strenuous exercise, the body will sweat significantly, further leading to the concentration of urine, resulting in the corresponding situation. 3. Stones: during strenuous exercise, small stones may be discharged from the body, during which the ureter wall may be scratched, causing the corresponding symptoms. 4. Menstruation: If a woman happens to be in her menstrual period, the discharge of menstrual blood with strenuous exercise will also cause the corresponding situation. 5. Gynecological inflammation: gynecological inflammation accompanied by mucosal injury, small capillary rupture, there will be bloody secretions along with urine discharge during exercise, causing the corresponding conditions. Hematuria after strenuous exercise may also be caused by other factors, if the hematuria persists unrelieved, and accompanied by low back pain, you need to consult a doctor in time, after diagnosing the specific physical condition, under the guidance of the clinician to standardize the treatment, to avoid causing delays in the condition.