The study, which was funded by the US National Institutes of Health to the tune of 400,000 dollars, was the work of Dr Kimberly Williams, research assistant professor in the Department of Community Medicine at West Virginia University in Morgantown, and colleagues, and can be read online in the 1 September issue of the journal Spine.
Low-back pain is the largest category for medical reimbursements in the US, accounting for 34 billion dollars of medical costs every year, said the researchers.
The three-year study showed that the group that did yoga had lifted mood, less pain and improved function compared to the control group that received standard medical therapy.
Proponents of yoga have often described how it helps back pain, but not everyone was convinced so Williams and colleagues conducted this research, which they say is the biggest and most rigorous evaluation ever done.
Williams told the media that:
"The yoga group had less pain, less functional disability and less depression compared with the control group."
"These were statistically significant and clinically important changes that were maintained six months after the intervention," she explained.
For the study, Williams and colleagues recruited 90 people who had mild to moderate functional disability due to chronic lower back pain.
The participants were randomly assigned to have either yoga instruction or conventional medical therapy.
The yoga group were taught by Iyengar certified instructors for 90 minutes twice a week for 24 weeks. During the classes they did postures that targeted chronic low back pain.
The researchers continued to monitor the participants for 6 months after finishing yoga or medical therapy.
The researchers took outcome measures using the Oswestry Disability Questionnaire, a Visual Analog Scale, the Beck Depression Inventory, and a pain medication-usage questionnaire half way through the treatment phase (12 weeks), immediately after (24 weeks) and at week 48 (6 months after treatment finished).
The results showed that:
- At the end of the treatment phase (24 weeks), significantly greater reductions in functional disability and pain intensity were observed in the yoga group compared to the control group (using intention-to-treat analysis with repeated measures ANOVA for group x time).
- A significantly greater percentage of the yoga group members also reported clinical improvements half way through and at the end of treament (12 and 24 weeks).
- The yoga group also showed signficiantly improved scores for depression.
- Both groups reduced medication by about roughly the same amount.
- Analysing the results on a therapy by therapy basis showed that all outcomes improved in the yoga group, including a greater trend for reduction in use of pain medication.
- Although the improvements were slightly better at the 24 week stage, at the end of the 6 months of follow up the yoga group showed statistically significant reductions in functional disability, pain intensity, and depression compared to the group that received standard medical care.
"Yoga improves functional disability, pain intensity, and depression in adults with CLBP [chronic low-back pain]."
"There was also a clinically important trend for the yoga group to reduce their pain medication usage compared to the control group," they added.
Iyengar Yoga is the most popular form of yoga in the US: it can be practised by anyobody no matter what their physical or mental ability, say its proponents.
Iyengar Yoga emphasizes postures and breathing that promote strength, flexibility and balance.
The underpinning philosophy of Iyengar Yoga is the Yoga Sutras of Patanjali, an Indian sage who lived about 1700 years ago. While the goal of the postures is to create peace of mind and harmony and prepare for meditation, many people, particularly in the Western world, use Iyengar Yoga to improve physical and emotional fitness and wellbeing.
The name Iyengar comes from Yogacharya Sri B.K.S. Iyengar who was born in India in 1918 and has been studying and practising Yoga continuously for over 70 years. He is based at and runs the Ramamani Memorial Iyengar Yoga Institute in Pune, India with his son and daughter.
There are over 2,000 qualified Iyengar Yoga teachers in the world, in over 40 countries.
"Evaluation of the Effectiveness and Efficacy of Iyengar Yoga Therapy on Chronic Low Back Pain."
Williams, Kimberly, Abildso, Christiaan, Steinberg, Lois, Doyle, Edward, Epstein, Beverly, Smith, David, Hobbs, Gerry, Gross, Richard, Kelley, George, Cooper, Linda.
Spine, 1 September 2009 - Volume 34 - Issue 19 - pp 2066-2076.
Sources: West Virginia University, Iyengar Yoga Association of the UK.