The cause of dizziness after running 800 meters may be caused by low blood sugar, because the activity is relatively large, more consumption, resulting in a drop in blood sugar, the brain is more sensitive to ischemia, lack of oxygen, the lack of energy supply will appear dizzy symptoms. 1, dizziness after running 800 meters may also be caused by elevated blood pressure, because of strenuous activity or mental tension, anxiety, blood pressure will also be elevated to cause patients to appear dizzy symptoms. 2, the problem of dizziness after running 800 meters may also be due to the redistribution of blood, during strenuous exercise, the blood supply to the muscles and other soft tissues will increase, resulting in a relative lack of blood supply to the brain, the patient will also show symptoms of dizziness, it is recommended that patients rest, dizziness symptoms can be quickly relieved.