Running knee pain may be related to soft tissue injury, patellar ligament inflammation, tibial tuberosity chondritis and so on. 1. Soft tissue injury: Excessive exercise can lead to injury of muscles, ligaments and other soft tissues below the knee, causing the symptoms of running pain below the knee. 2. Patellar ligament inflammation: long-term running and other sports can lead to inflammatory lesions of the patellar ligament, resulting in symptoms of pain under the running knee. 3. Tibial tuberosity chondritis: Tibial tuberosity chondritis is a sterile inflammatory lesion of the tibial tuberosity epiphysis, which makes the patient suffer from pain under the knee when running. Running pain below the knee can also have a variety of causes such as knee arthritis, synovitis, etc., it is recommended to go to the hospital in time to improve the relevant examination, after a clear diagnosis for treatment.