Sudden inactivity of the lower limbs may be caused by the following aspects: 1, it may be caused by low potassium, the most common is excessive sweating in summer, or acute gastroenteritis, abdominal pain, diarrhea, vomiting more, resulting in the loss of potassium, the emergence of low potassium, resulting in the loss of muscle strength of the limbs, the emergence of the phenomenon of sudden inactivity of the lower limbs.2, it may be caused by cerebrovascular accidents, common is acute cerebral infarction or acute cerebral hemorrhage, this situation is usually unilateral inactivity of the lower limbs, accompanied by unilateral decline in muscle strength of the upper limbs. Acute cerebral infarction or acute cerebral hemorrhage, this situation is generally unilateral lower limb inactivity, will be accompanied by unilateral upper limb muscle strength decline. 3, may be caused by lumbar spine disease, sudden lumbar disc herniation compression of the spinal cord, there may be lower limb numbness, fatigue, resulting in sudden inactivity.