Applied Evidence

Yoga as therapy: When is it helpful?

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The evidence for yoga’s benefits for specific conditions


The promotion of yoga as medical treatment is rife with dubious claims, but there is solid evidence for its benefits in some common conditions. The evidence summaries that follow reflect searches on Medline, via PubMed, and the Cochrane Database using the phrase “yoga review.”

Back pain

Often a stress-related musculoskeletal problem, back pain seems an appropriate indication for treatment with yoga, and there is a large body of literature on the subject.5 In a systematic review, Chou and Huffman6 found only 3 studies meeting inclusion criteria on yoga’s effectiveness for subacute or chronic low back pain. One large study found 6 weeks of Viniyoga was superior to conventional exercise programs and a self-care booklet in reducing pain and “bothersomeness” scores, as well as reducing the need for analgesic medication.7 Physician visits for back pain were not reduced in the treatment group, however.7 Also included in the systematic review were 2 smaller studies of Iyengar yoga on low back pain; results did not rise to statistical significance.6

A review by Posadzki and Ernst8 included 4 randomized controlled trials (RCTs) not included in Chou and Huffman, although only one of these had >50 subjects. Yoga practices for the treatment groups were mostly Iyengar and Viniyoga and lasted for 12 to 24 weeks, although one study used a 7-day intensive inpatient treatment program. Yoga practitioners had lower pain scores and lower Roland Morris Disability scores.8 A 2004 Clinical Inquiry in The Journal of Family Practice found limited evidence to suggest yoga may speed healing for patients with chronic back pain.9

Most recently, Cramer et al10 found 12 studies meeting inclusion criteria that reported on Viniyoga, Iyengar, and Hatha yoga interventions. Ten of these studies were included in the meta-analysis, which strongly favored yoga over control interventions for reducing pain and disability scores.10

Depression and anxiety

Iyengar yoga and Viniyoga have been shown
 effective in reducing chronic low back pain.Yoga therapy for depression and anxiety has been commonly studied, given that aspects of mindfulness and relaxation are thought to be important parts of treatment. Moreover, patients uncomfortable with pharmacologic therapy for their disorders may be amenable to yoga treatment. In a recent Clinical Inquiry, Skowronek et al11 found evidence (strength of recommendation [SOR] B) for yoga to treat depression and anxiety symptoms based on 3 recently published review articles that commented on a total of 23 RCTs.

A handful of additional review papers on this subject have selected slightly different groups of studies to include in their analyses, but all have found generally positive results.12-14 Inclusion criteria varied: one review omitted breathing-only modalities such as Sudarshan Kriya yoga, while another included them.12,14 One omitted Mindfulness-Based Stress Reduction (MBSR), which is a program developed in the United States based on several Eastern and Western methodologies including yoga.12 MBSR already has a large body of literature supporting its use for anxiety and depression.12

One of these reviews,12 which involved a meta-analysis of 9 studies regarding depression, also included a meta-analysis of 5 studies on yoga for anxiety. Pooled results for depression showed significant benefit for yoga over usual care, and smaller but still significant benefit for yoga over aerobic exercise or other relaxation techniques. For anxiety, pooled analysis showed yoga to be equal to usual care but superior to other relaxation modalities.12 As with earlier reviews, study groups were heterogeneous and included young and older adults, caregivers for dementia patients, and those receiving inpatient treatment for alcohol dependency; symptoms of depression ranged from mild to severe.12

In a review focusing on anxiety disorders, Kirkwood et al15 located 8 trials, 6 of which were randomized. Many of these were published in the 1970s and 80s. The yoga interventions varied and included weekly Kundalini sessions, pranayama techniques, and savasana (a pose in which practitioners lie supine while focusing on breathing and muscle relaxation). These practices were compared with anxiolytic medication, progressive muscular relaxation, placebo capsule, and no treatment. All found a statistically significant reduction in anxiety indices in the yoga treatment groups, and the authors noted that the positive effects of yoga for those suffering from obsessive-compulsive disorders are particularly well documented.15 More recently, Li and Goldsmith16 reviewed 6 interventional studies that included some trials without randomization, blinding, or a control group. Subjects of the studies included cancer patients, postmenopausal women, pregnant women, and firefighters. Six of 9 trials showed improvement in externally validated anxiety indices such as the State-Trait Anxiety Inventory or Perceived Stress Scale.

Asthma

With its focus on awareness of breath and the mechanics of breathing, yoga would seem a natural adjunct to conventional asthma therapy. One systematic review found 4 trials (3 RCTs) that showed statistically significant improvements in spirometric measurements in patients with asthma who practiced yoga techniques.17 An additional 3 RCTs showed no improvements with yoga over conventional treatments.17 Overall, the reviewers noted that study quality was poor, although they said several studies were appropriately designed. Again, the interventions described as “yoga” varied considerably, from Iyengar-type classes to meditation-focused techniques to pranayama exercises. Follow-up ranged from 6 weeks to 6 months.17

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