Lumbar flash is mainly inadvertent process of severe pain, such as in the process of drying clothes, a slight activity waist appears waist of severe pain, pain is induced in a certain position, such as lying down or sitting on a sofa with a backrest, pain can be significantly relieved is flash back. Sprain is in the process of doing sports or doing exercise muscle sprain, muscle sprain pain persists, that is, no matter what kind of action, the pain persists, even when resting in bed, the pain is only a little relief, the above is the difference between waist flash and sprain.