A common cause of knee pain while running is iliotibial band syndrome (ITBS). Individuals with this problem will experience symptoms at the level of the knee cap and outer aspect of the knee. The ITB is a thick fibrous band that runs from the outer muscles of the hip, down the thigh, and attaches to various structures around the outside of the knee, including the kneecap and hamstring.
When you step onto your left foot, the left outer hip muscles and ITB hold the pelvis level. If there is injury or weakness of the outer hip muscles, the pelvis will drop to the right. All of the left side structures, including the ITB, will be placed on stretch. The tight ITB pulls on the knee cap and rubs across the bone at the knee. With time and repetitive activities, like running and cycling, friction and poor tracking occur causing symptoms.
The ITB is NOT a muscle. The ITB depends on the hip muscles to help it do its job of stabilizing the pelvis. In order to stop the knee pain, the muscles of the hip must be assessed and treated to restore normal function.
If you have knee pain when running it is wise to have your local physiotherapist help you understand the problem and how to best manage it so that you can keep putting one foot in front of the other!