You are a cross country runner who trains three times a week with the same training regime. However, after completing this regime for a number of weeks, you decide to intensify your training, running a longer distance every day in preparation for an upcoming marathon. Due to the repetitive, high - impact motion putting stress on the knees, you develop runner's knee - patellofemoral pain syndrome - due to friction that wears down the cartilage in the knee. Runner's knee presents pain in, around or behind the kneecap and feels stiff when standing after resting for long periods of time.