Do you have a running injury?

ITB Syndrome can affect runners; it runs from the outer hip to just below the outer knee.

It helps to absorb running impact and stabilise the knee.
When tight it can affect running posture and ability.
If tight complete 30-45 secs of ITB foam rolling – Lie on your side with a foam roller mid thigh, roll toward the top of the knee and then back to the hip.
Try to not roll onto the hip or knee joint.

See an instructor for assistance and to ensure correct technique.
Also strengthen the glutes with single leg squats, keep the knee pointing forward and hips level.
Use a mirror to ensure correct technique.