A variety of reasons can trigger the weakness of the legs, of which the more common ones are over-exercise, malnutrition, the presence of orthopedic or vascular lesions and other diseases. 1. Excessive exercise: patients with recent fatigue, excessive exercise intensity or lack of exercise, sudden intense exercise may trigger the accumulation of lactic acid in the legs, which is manifested by the soreness of the legs and the inability to develop strength. Appropriate rest can relieve the symptoms. 2 Malnutrition: If the patient has low blood sugar, insufficient potassium, calcium and anemia, the legs will be sore and weak. 3 Orthopedic diseases: If the patient has knee arthritis, the legs will be sore and weak at the same time as the knee pain. Lumbar disc herniation and cervical spondylosis patients, the spinal cord may be compressed to affect the lower limbs, the specific performance is also the legs movement inconvenience, soreness and weakness. 4 vascular disease: for example, atherosclerosis will make the blood vessels narrow, bilateral lower limb blood supply is insufficient, will produce the symptoms of weakness, soreness and even pain in the legs. In addition, if the lumbar intervertebral disc disease, neurological diseases may appear the symptoms of two legs soreness and weakness, it is recommended that the two legs soreness and weakness of the patient as soon as possible to seek medical treatment, screening and diagnosis. According to the specific cause of the targeted treatment.