After running, the pain below the knee is considered to be overstrain, patellar tendonitis, tibial tuberosity chondritis and so on. Excessive strain, the weight of the knee joint during running is about four times that of the human body, and prolonged running aggravates the burden on the knee joint, which can cause wear and tear of the cartilage inside the knee, and strain of the muscles, tendons, and ligaments below the knee, leading to pain below the knee after running, accompanied by oozing of local tissue fluids and edema. Patellar tendonitis, long-term running can cause repeated stretching of the patellar tendon, resulting in inflammatory oozing from the patellar tendon area, leading to pain. Tibial tuberosity chondritis, if children or adolescents present with pain below the knee, consider that the tibial tuberosity cartilage has been repeatedly stretched during running, resulting in aseptic inflammation that leads to pain. If the pain below the knee persists after running, it is recommended to actively seek medical attention and treatment under the guidance of a physician.