What is Runner's Knee?
Runners, jumpers, and other athletes such as skiers, cyclists, and soccer players put heavy stress on their knees. Runner's knee is a term used to refer to a number of medical conditions that cause pain around the front of the knee.
With runner's knee, instead of your knee moving up and down in a narrow groove on your thighbone, it moves out of its tracks and rubs up against the sides of the groove. This could be caused by weak thigh muscles (quadriceps), wearing the wrong shoes for your foot strike, or because of a training error like too much mileage or speed work.