What are the benefits of chiropractic therapy for lower and middle back pain?

None: Useful for massage. No scientific evidence of any genuine benefit has ever been shown. Probably feels good. Do it if it feels good to you and you feel like the money you are spending is worth it. Physically helpful? Not really. Physical therapy would be a far better choice.

Good Benefit: Research shows for spinal conditions chiropractic adjustments and rehabilitation over the long term are best. Doctors of Chiropractic are being trained in and are specialists of both spinal manipulation and rehab. There is much research, unfortunately it is impossible for clinician's to keep up in their own field, let alone someone else's specialty. Check out www.chiro.org/research