Back pain and running go together because the movement of the leg moving up requires the use of the sacroiliac joint (also called the SI joint). Ideally, when your right leg moves up, the right SI joint moves back.
However, for a lot of people, this joint becomes stuck or locked up and the movement is no longer as smooth and pain-free as it should be or could be. Any time a joint is unable to work as it’s designed it will inevitably lead to pain.
When the SI joint doesn’t work as it is designed, it usually leads to low back pain and hip pain. Many people believe the SI joint is not a movable joint, but this is simply not the case.
Restoring the normal movement to this area and then strengthening the surrounding muscles with specific posture exercise go a long way in stabilizing the area and reducing the likelihood of a re-aggravation of pain in this are.
Another overlooked aspect to back pain and running is the need to adequately stretch following a run. Many remember to stretch before (even though most experts believe you should walk or lightly job to warm up before a run), but do not stretch after they run.