A herniated lumbar disc may cause weakness in the heel. When a lumbar disc herniation occurs in the lumbar 4/lumbar 5 and lumbar 5/sacral 1 spaces, it can compress the sciatic nerve, which innervates muscle movement in the legs and feet. When the sciatic nerve is compressed by a herniated lumbar disc for a long period of time, it can result in weakening of the muscles of the legs, causing weakness in the legs and heels. Heel weakness due to a herniated lumbar disc is also accompanied by other manifestations of nerve root compression, such as decreased sensation in the back of the foot, and radiating pain from the outside of the thigh and calf to the heel. Mild cases can be treated with bed rest, pelvic traction and physical therapy; severe cases should be treated with surgery. Patients with herniated lumbar discs that cause heel weakness should go to the hospital in time and receive regular treatment under the guidance of a doctor.