The reason for this is mainly the following: 1. It may be caused by excessive nerve stimulation, as the nerve roots of the lumbar spine are compressed and stimulated in patients suffering from this disease, it will continue to produce radioactive pain in the lower limbs, when the muscles of the lower limbs receive abnormal stimulation for a long time, it is easy to cause muscle cramps here. 2. It may be caused by long-term muscle tension, in which the muscles of the lower limbs are often in a state of chronic stress due to painful stimulation, and remain very tense, which may cause fatigue over time and lead to cramps. 3. The patient may curl up one lower limb for a long time and inadvertently straighten the lower limb in the process of inducing severe nerve pain, which in turn leads to spasm of the lower limb muscles.