Lack of strength in legs may be related to overwork, hypokalemia, lumbar intervertebral disc herniation, lower limb neurovascular disease, cerebrovascular disease and other factors. 1. Overwork: Prolonged heavy physical labor and insufficient rest will lead to overwork of the body, resulting in the lower limb muscle tissues being completely depleted of energy and can be accompanied by a large amount of lactic acid accumulation, which will lead to the weakness of the legs and lack of strength. 2. Hypokalemia: improper diet, hyperthyroidism, prolonged vomiting and diarrhea may lead to low potassium in peripheral blood, affecting the normal electrical activity of muscle cells and reducing the excitability of muscle cells, which may lead to periodic paralysis, manifesting as weakness of legs, arrhythmia, abdominal distension, and so on. 3. Lumbar disc herniation: Lumbar disc fibrous ring rupture, nucleus pulposus prolapse and other conditions lead to lumbar disc herniation, the protruding disc stimulation and compression of the spinal cord, which can cause weakness of the lower limbs, walking with a feeling of stepping on cotton and other symptoms. In addition, the lack of strength in the legs may also be related to lower extremity neurovascular disease and cerebrovascular disease and other factors. It is recommended that patients with leg weakness should consult a doctor in time and follow up with targeted treatment under the guidance of a specialist.