The study authors took two groups of patients and compared yoga to usual care for chronic or recurrent low back pain. All patients received a back pain education booklet, but the study group also received a gradually progressing yoga program delivered by 12 teachers over 3 months. The teachers were from 2 yoga associations - The British Wheel of Yoga and Iyengar Yoga and the sessions they taught were the same. They focused on foundational elements of yoga that were adapted for low back pain. The poses targeted stiff, weak and uneducated areas of the whole body with the intention of improving mobility, strength and posture, while reducing pain.
The yoga group participants continued to have better back function at 3, 6 and 12 months than the patients in the usual care group. The benefits of yoga did diminish after 12 months when only 60% of the participants continued with home yoga. But 60% is a pretty high rate for continuing a practice!
Despite the fact that the most benefit was observed during the group Yoga and within 3 months afterward, even at 12 months the benefits persisted, especially in those patients who continued the practice. Yoga was safe and effective for treatment of low back pain.
Here is my favorite low back yoga position:
I recommend a book called Yoga as Medicine by Timothy McCall, MD