Start with the easy options such as changing your shoes. If your running shoes are worn out or not suitable for you they will not absorb the constant shock of the impact with the road causing compression and jarring in the discs in your spine. Visit a good running shop and ask to have your running technique assessed so they can recommend the best shoe for you.
If changing your running shoes does not help get yourself checked out by a physical therapist for any hidden injury problems. If you still experience back pain whilst running the most sensible thing to do is to assess your technique.
For most runners it’s lower back pain that causes the most problems. I believe there are two main causes for this in relation to running technique.
Trying to hold the torso upright in the style of Michael Johnson by tightening the lower back muscles. It is now accepted by most coaches that Johnson’s upright technique, once considered unconventional, is a very efficient way to run. However, if you look at how Johnson’s technique evolved you will see that he used his lower back less and less to achieve it.
To achieve an upright running style without tightening your lower back you need to ‘let go’ of the muscles likely to collapse your torso forward. The latissimus dorsi muscles are then able to perform their proper function to maintain your ‘effortless up’ – this will take all the stress off your lower back.
Another cause of lower back pain for runners is the thought that running is about going forward, okay of course it is, but it doesn’t require you to ‘push’ forward to do it. Running is really about passing a force into the ground and using the hip, knee and ankle joints to translate that into a forward motion.
Your running technique could be the cause of your problem. Once you can develop an efficient, relaxed style you may find that running and back pain are no longer mentioned in the same breath.