Lumbar pain after breaststroke may be caused by physiological reasons such as overwork, or it may be caused by pathological reasons such as lumbar muscle strain, lumbar sprain and aggravation of lumbar spine disease. 1. Excessive fatigue: Because breaststroke requires coordinated movement of lumbar muscles, it can cause spasm of lumbar muscles or local products can not be absorbed in time after a long period of swimming, so the patients can have lumbar pain after breaststroke. 2. Lumbar muscle strain: common in long-term breaststroke and other lumbar activities, due to repeated muscle contraction, strain, the patient lumbar muscles and other tissues of chronic cumulative injury, which can lead to lumbar pain after breaststroke. 3. Lumbar sprain: some people exert too much force or have incorrect posture during breaststroke, which causes acute sprain of lumbar muscles and other tissues, and thus patients have lumbar pain after breaststroke. 4. Lumbar spine disease: commonly seen in lumbar disc herniation, lumbar spine slipped, lumbar spine infectious disease, the activity of lumbar region during breaststroke causes local inflammation or nerve irritation, which leads to the aggravation of pain symptoms after breaststroke. There may be other reasons for back pain after breaststroke, so it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy.