The waist uninterruptedly flash like a cramp may be due to lumbar muscle strain, cold and other physiological reasons, may also be due to acute lumbar sprain, lumbar degenerative disease and other pathological reasons. 1. Physiological reasons: long-term stooping labor, cold and sedentary factors, can cause lumbar myofascial tension and spasm, resulting in lumbar muscle strain, the phenomenon of cramps. Appropriate rest and lumbar warmth can gradually relieve the symptoms. 2. Acute lumbar sprain: the lumbar region is subjected to sudden external force, which may lead to acute lumbar sprain, causing pain and spasm in the lumbar muscles, which may also be manifested as symptoms of cramps. 3. Lumbar degenerative disease: lumbar spine degenerative disease, will lead to vertebral instability, local muscle tension compensation or compression of the nerve, can also lead to the emergence of the above symptoms, common such as lumbar intervertebral disc protrusion, lumbar vertebral spondylolisthesis, and so on. The symptoms of lumbar cramps alone sometimes can not accurately determine the cause, but also need to be combined with the characteristics of the medical history, other test results in order to make an accurate judgment, it is recommended that the cause of the disease under the guidance of the doctor to clarify the cause of the disease and then carry out targeted treatment.