The main reasons for left leg weakness and shivering are related to muscle fatigue, strains and neurological lesions. 1. Muscle fatigue: usually, if the long time weight-bearing exercise, or overwork, the left leg muscle force more left leg muscle fatigue, easy to produce lactic acid accumulation of excessive phenomenon, so as to appear the symptoms of the left leg soreness and shivering. 2. Strain: If there is a local muscle soft tissue strain in the left leg, it is easy to produce localized symptoms of soreness and tenderness, and at the same time, it affects the motor function and produces a decrease in the stability of the lower limbs, which is accompanied by the symptom of shivering. 3. Neurological lesions: when there is a nerve injury in the left lower limb or lumbar spine lesions compressing the nerve root such as lumbar disc herniation, lumbar vertebral body slippage and pyriform muscle syndrome, etc., it is easy to affect the motor and sensory function of the left leg nerves and thus the symptom of shivering in the left leg. If the symptoms of left leg pain and shivering last for a long time, you need to check the specific cause of the disease, to exclude whether there are varicose veins in the lower limbs, arterial embolism and diabetes complications and other diseases. Under the guidance of professional physicians to carry out targeted treatment to prevent the worsening of symptoms.