One of the most common causes of back pain is poor posture. The body gets used to being held in a certain position, one that puts a lot of pressure on one part of the spine, typically the lumbar spine, and, over time the strain develops into a muscolo-skeletal problem resulting in acute pain.
By the time back pain becomes a problem, the postural problems are most probably in a chronic phase. The body's muscle memory has got so used to holding the body in that poor posture that the body thinks that that is a normal state to be in. You might even think that that's a normal state for the body and spine to be in, having got used to it over a period of years.
The body's muscles need to be re-trained to hold the body in the correct posture, and this correct posture will relieve a lot of back pain because a correctly aligned spine will be carrying the body's weight the way it was designed to.
Regular practise of Taijiquan helps to relieve the stress on the spine and its supporting muscles. Relaxation and correct alignment re-train the body's supporting muscles. Emphasis is placed on alignment and relaxation. Both are needed to start the process of re-training the body to hold itself correctly. Relaxation allows the back and spine to be more mobile, thus relieving pressure on the vertebrae and discs which helps prevent discs from slipping. The muscular relaxation also prevents muscles from becoming over-stressed from having to carry too much tension.
Once the body starts to relax, the body can then change its alignment as the added range of motion will make the muscles and skeleton slightly more malleable allowing the spine to move into the correct shape to carry the body.
Taijquan form is very slow, gentle and low-impact, so the gentle flex and twists in the form will gradually work the large supporting muscles of the core, perturbing them as it were and allowing them to relax temporarily as other muscles take over the job of supporting the body whilst you are doing the form. The body will naturally relax in stages, because relaxation in one part of the body must be accompanied by adjustments everywhere else. Practitioners of Taijiquan typically report the process of relaxation taking place over a period of months or years. This stands to figure as the body cannot let go of the tension built up over a period of years in a matter of weeks.
It is important to note that relaxation of the big supporting muscles of the body allows more of the muscles of the core to work together to help support you, thus resulting in a lower weight load for each muscle on average. It is this that will allow you more flexibility in your spine and more range of motion, which will allow you to achieve better alignment and relieve yourself of back pain.
Massage and chiropractors are good solutions to acute back pain, but if the body is not somehow re-trained to support itself properly the misalignment and poor posture will remain, and this will inevitably cause more back pain in the future.
Regular practise of Taijiquan, even just 10 minutes a day is sufficient to begin this process. Regular practise is proven to me much more effective than concentrated bursts of an hour once a week. This is because the body needs to develop new supporting habits and new ways of coordinating itself, and regularity is the way to develop habit.
One does not need to be a Taijiquan master to relieve one's back pain. I managed to get some very good results just knowing the first section of the Yang 24 form. For a long time that was all I really practised, because I was getting such good results and back pain relief.
So, if you can set aside 10 minutes a day to practise a bit of Taijiquan form, you can help your back heal. This process is also like pushing a snowball, it will accelerate the more you practise because relaxation begets more relaxation and healing.