Dizziness and black eyes after strenuous exercise are mostly considered to be caused by insufficient blood supply to the brain, poor physical condition, low blood sugar, high blood pressure and other reasons. 1. Insufficient blood supply to the brain: blood is supplied to the body and limbs during strenuous exercise, which can easily lead to insufficient blood supply to the brain, resulting in dizziness and black eyes after strenuous exercise. 2. Poor physical fitness: long time not exercise leads to poor physical fitness, after sudden strenuous exercise, the organs of the body can not adapt, there is insufficient oxygen supply, thus appearing dizziness and black eyes. 3. Hypoglycemia: after strenuous exercise, a large amount of glucose is consumed by the body, resulting in hypoglycemia, causing insufficient energy in the brain, which makes it easy to experience dizziness and black eyes. 4. High blood pressure: after strenuous exercise, the body has a greater demand for blood oxygen, the heart speeds up the heartbeat so that the blood pressure rises, which may cause the original high blood pressure patients with abnormally high blood pressure, dizziness and black eyes. It is recommended that excessive strenuous exercise should be avoided in daily life, and if the dizziness and black eyes are serious, it is recommended to consult a doctor in time.