Applied Evidence

Yoga as therapy: When is it helpful?

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References

A more recent and thorough review found 14 RCTs using yoga to treat asthma symptoms.18 The investigators performed pooled analysis despite significant heterogeneity in the studies. The analysis showed some improvement in the yoga group compared with usual therapy, but no difference in comparison with sham yoga or non-yoga breathing exercises.18

Symptoms of menopause

Studies have focused on alternative or adjunctive therapies for menopause symptoms, primarily hot flashes, since hormone replacement therapy and other conventional medical therapies have been found to have a high incidence of adverse effects. However, evidence that yoga can reduce hot flashes is sparse.

A Cochrane review examined the effects of exercise on hot flashes and found 2 RCTs using yoga as a treatment modality. Neither one found statistically significant differences between the yoga groups and conventional exercise groups.19 The authors concluded there was insufficient evidence to show yoga was more effective than other forms of exercise on vasomotor symptoms of menopause. However, a large RCT included in the Cochrane review did show lower stress levels and decreased overall symptoms in the yoga arm.20

The yoga intervention in this study consisted of pranayama, sun salutation (a repetitive sequence of 12 yoga postures), and cyclic meditation.20 Lee et al21 reviewed the 2 studies used in the Cochrane paper as well as 5 other studies. Two were RCTs showing that yoga intervention was not superior to a no-treatment control. Four studies showed favorable results for yoga interventions; however, one was a nonrandomized controlled trial and 3 lacked control groups.

Cramer et al22 attempted pooled analysis of 5 studies, including those in the Cochrane paper, with similar results: Yoga interventions were not efficacious for somatic, vasomotor, or urogenital symptoms of menopause. Yoga was somewhat efficacious for psychological symptoms associated with menopause.22 More recently, an RCT (N=249) found that yoga reduces vasomotor symptoms no more frequently than non-yoga exercise.23

Hypertension

Yoga is often said to reduce blood pressure (BP), which would make sense given the emphasis put on relaxation by many schools of yoga. In the past 2 years, 3 review articles have been published, as well as 2 relevant RCTs not included in those reviews.

Hagins et al24 found 17 RCTs using yoga to treat adults with hypertension and prehypertension. These included both blinded and unblinded studies, and yoga interventions were compared with usual treatment, education, or non-yoga exercise. The authors included only studies of asanas intervention, and excluded interventions using only breathing or relaxation techniques.24 In meta-analysis, pooled data showed the yoga treatment decreased both diastolic BP (DBP) and systolic BP (SBP) by 3 to 4 mm Hg compared with usual treatment, but not when compared with other exercise therapies.24 Reviewers concluded that yoga was likely as effective for lowering BP as other types of physical activity.24

In a review without meta-analysis, Posadzki et al25 also found 17 blinded RCTs using yoga to treat hypertension or prehypertension in adults. Eleven of the 17 studies favored yoga, with 8 showing a decrease in SBP and 5 in DBP.25 All but 2 studies were found to be of poor quality, especially with regard to blinding.25 The authors noted that studies using subjects with prehypertension or hypertension with comorbidities were more likely to show significant results, speculating that yoga may be more effective for these populations.25

In an ambitious review article on yoga as treatment for a variety of risk factors for cardiovascular disease, Cramer et al26 located 28 RCTs that addressed effects of yoga on BP. Seven of the studies in the Posadzki review25 were included. Meta-analysis showed a statistically significant decrease in SBP of 5.85 mm Hg and in DBP of 4.12 mm Hg.26 Although wide in scope, this meta-analysis included many studies of healthy patients without hypertension who could conceivably have differing neuroendocrine responses to yoga practice.

Search engines offered by the Yoga Alliance and the International Association of Yoga Therapists can help patients to locate a yoga instructor or therapist in their area.In a pilot RCT, Cohen et al27 found a significant decrease in BP among subjects randomized into Iyengar yoga classes for 24 weeks compared with a control group educated about lifestyle modification. A larger study with 102 subjects is currently underway.28 These studies were unique in that no subjects were currently being treated with antihypertensive medications27,28; most other trials on this subject enrolled participants on antihypertensive medications if their regimens had been stable for some time.

In an RCT published recently by Hagins et al,29 68 subjects with pre- or stage I hypertension were randomized into Ashtanga yoga classes or non-aerobic exercise classes formulated to burn equivalent METs. After 12 weeks of treatment, the yoga subjects’ BP had significantly decreased from starting values, but was not improved compared with the exercise subjects.29 This further supports the assertion that yoga is equivalent to other forms of physical activity in decreasing BP among hypertensive subjects.

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