Thanks for your explanation, streif.
From the description you gave, it sounds like a maneuver that we chiropractors call a "million dollar roll." I don't really like the procedure... particularly the part about pushing the shoulder back. This puts a torque stress on the entire spine from the shoulder to the pelvis.
A "side posture" adjustment like you described should actually have very little rotation to it, and the forces should be focused and isolated to only 2 or 3 segments in the lumbars to correct the one (or occassionally, two) subluxations in the lumbo-sacral area. And 98% of the time, it only needs to be performed in one direction, when it's done properly.
This "million dollar roll" maneuver is one major reason that many people with low back problems won't find benefit from chiropractors who perform it. While some patients may feel a temporary relief from the "cracking," the biomechanical stress of the movement (called "uncoupling") can potentially set the stage for more instability and weakness in the spinal tissues in the future.
streif, are you currently doing any other exercises besides running and spinning? Getting adjusted by your chiropractor, while it has its benefits, is not the only component to keeping a strong and healthy back. (strong and healthy body, for that matter) If you're experiencing back pain while running, then it's important to incorporate proper stretching and strength training into your routines, no matter what medical treatment or therapy you're getting.
Since I don't know for sure exactly what your chiropractor is doing for your low back, nor do I know the proper diagnosis of what's causing your back pain... my advice would be to ask him to explain to you what he's accomplishing with procedure he's doing. If he's trying to "put bones back into place" or "free up stuck joints," that's probably not going to help your back to heal. If he's trying to correct imbalances in the lumbar joints and help normalize movement patterns, then what you described is being done to you is too forceful to accomplish that.
The human spine doesn't require much manipulation or force to correct and heal itself. I have found that when it comes to the human body and its spine, a whisper can awaken somebody's inborn potential much more effectively than a shout.
comprex... that's a good website. Thanks for sharing!