Weakness of limb muscles is not necessarily caused by diseases, it may be caused by physiological factors, or brain diseases, spinal cord diseases, peripheral neuropathy, hypokalemia and so on. 1. Physiological factors: If one is weak, malnourished, overworked, etc., generalized weakness may occur, which can be relieved by resting and supplementing nutrition. 2. Brain diseases: when the patient suffers from encephalitis, cerebral ischemia, intracranial tumors and other diseases, it can involve the bilateral pyramidal fasciculus, resulting in symptoms of limb weakness. 3. Spinal cord disease: if the patient has spinal cord cervical spondylosis, acute myelitis, spinal cord vascular disease, spinal cord cavernous disease and other diseases, the symptoms of limb muscle weakness may occur, and may also be accompanied by incontinence and other symptoms. 4. Peripheral neuropathy: If Guillain-Barré syndrome occurs due to immune abnormality, there is muscle weakness in the limbs, accompanied by sensory loss, and the cerebrospinal fluid shows the phenomenon of protein-cell separation. 5. Hypokalemia: when hypokalemia occurs, the symptoms of limb weakness can also appear, generally the lower limbs are heavier than the upper limbs. Patients with muscle weakness of the limbs should go to the hospital in time, and follow the doctor’s instructions after clarifying the cause of the disease.