Knee pain after exercise may be due to physiological reasons such as soft tissue strain, or patellar tendonitis, synovitis, meniscus injury, osteoarthritis and so on. 1. Soft tissue strain: excessive or strenuous exercise may lead to muscle or ligament strain, strain, and generally recover after rest. 2. Patellar tendonitis: mainly pain in the front and lower part of the knee joint, especially the pain is aggravated by frequent jumping or running. 3. Synovitis: synovial hyperplasia and hypertrophy occurring aseptic inflammation joint pain, joint swelling. 4. Meniscus injury: meniscus tear when the movement, meniscus and cartilage friction pain. 5. Osteoarthritis: joint degeneration, cartilage degeneration, narrowing of the joint space, knee pain when exercise. If often occur after exercise knee pain need to go to the hospital orthopedic examination, clear cause for further treatment.