Yoga is a Controlled motion exercise, and a new metastudy looked at its effect on low back pain. Investigators found strong evidence for short-term effectiveness, and moderate evidence for long-term effectiveness when they looked at a total of 967 chronic low back pain patients. (The StrongPosture™ protocols incorporate yogic and rehab concepts into a clinical framework, so I really liked these findings)
Cramer H, Lauche R, Haller H, Dobos G. A systematic review and meta-analysis of yoga for low back pain. Clin J Pain. 2013;29:450-460.