Sitting for a long time leg swelling may be muscle pulling and other physiological factors, may also be lumbar spine lesions, vascular lesions of the lower limbs, heart disease, kidney disease and other pathological factors. 1. Physiological factors: common in sitting for a long time caused by the thigh or calf muscles are pulled for a long time, muscle tension, the patient may appear leg swelling. 2. Lumbar spine lesions: due to lumbar spine lesions compressing the nerve roots innervating the lower limbs, patients can experience leg pain, fatigue, soreness and swelling after sitting for a long time. 3. Lower extremity vascular lesions: lower extremity venous thrombosis, varicose veins of the lower extremities and other diseases, causing poor blood circulation in the lower extremities, thus causing the patient to sit for a long time with the feeling of leg swelling. 4. Heart disease: common in patients with cardiac insufficiency and heart failure, patients due to reduced blood flow back to the heart, sitting for a long time blood accumulation in the lower limbs, thus causing swelling of the lower limbs, often accompanied by chest tightness, shortness of breath, abdominal distension and other symptoms. 5 kidney disease: common in chronic nephritis, renal failure, nephrotic syndrome and other diseases, caused by sodium retention in the body can cause patients to sit for a long time leg swelling. Sitting for a long time leg swelling may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, give targeted treatment or treatment.