e4-11: Yoga

According to the National Center for Complementary and Integrative Health, yoga is a mind-body practice with origins in ancient Indian philosophy. The various styles of yoga typically combine physical postures, breathing techniques, and meditation or relaxation. There are numerous schools of yoga in the United States and around the world. Hatha yoga emphasizes postures (asanas) and breathing exercises (pranayama). Some of the famous styles of hatha yoga are Iyengar, Ashtanga, Vinyasa, and Kundalini.

According to the 2017 NHIS survey data, the percentage of adults who practice yoga in the United States has increased substantially, from 9.5% in 2012 to 14.3% in 2017.

Many yoga teacher training programs exist. To standardize yoga teacher training in the United States, the nonprofit Yoga Alliance provides a set of educational standards for yoga schools. A teacher trained through a Yoga Alliance-certified school has RYT (Registered Yoga Teacher) after their name according to the following hierarchy:

1. RYT 200 (this is the minimum level of teacher training signifying that the teacher graduated from a Yoga Alliance-approved 200-hour training).

2. RYT 500 (this level signifies graduating from a 500-hour training plus having 100 hours of teaching experience).

3. E-RYT 200 ("E" stands for "experienced." This designation level means the teacher has 1000 hours of teaching experience and has taught for at least 2 years).

4. E-RYT 500 (this level indicates 2000 hours of teaching experience and that the teacher has taught for at least 5 years).

There are also two specialty designations, RCYT (Registered Children's Yoga Teacher) and RPYT (Registered Prenatal Yoga Teacher), with specific training requirements. All RYTs must complete continuing education hours every 3 years.

There are many styles of yoga, so when referring patients to a yoga program, note these keywords that suggest the yoga class may be safe and gentle for medical/surgical patients: "restorative yoga," "therapeutic yoga," and "gentle yoga." Other styles may be appropriate but may depend on the teacher. The term "hatha yoga" is nondescript. "Hatha" is a classic yoga term denoting the postures ("asanas") that are central to most yoga practice. "Hatha yoga," generally connotes a beginner-level class that is not too strenuous; however, this should be confirmed with the teacher before participation.

Like any physical activity, there is a risk of injury with yoga practice. No comprehensive study has been done to assess the risks of practicing yoga, but strains, injuries to the trunk, and injuries in older participants appear to be most common. The most common adverse event was musculoskeletal (mostly minor sprains and strains), followed by neurologic (mostly transient paresthesia and headache). The headstand posture caused the most reported injuries, followed by the shoulder stand and lotus position.

A. Cancer

Most RCTs evaluating the effects of yoga on cancer patients have exclusively enrolled patients with breast cancer. The early studies are heterogeneous and have various methodologic shortcomings; however, there have been higher quality studies more recently. Overall, the psychological outcomes in these studies are consistent in showing benefits of medium effect sizes. A 2021 systematic review and meta-analysis of yoga for depression and anxiety symptoms yielded 26 studies (n=1486) for depression and 16 studies (n=977) for anxiety. Meta-analyses found significant medium effects for depression and anxiety. Physical outcomes are less consistent and demonstrate smaller effect sizes. Fatigue has been studied in multiple RCTs, and a systematic review concluded: "Yoga may be beneficial for reducing cancer-related fatigue in women with breast cancer; however, conclusions should be interpreted with caution as a result of bias and inconsistent methods used across studies." A 2020 systematic review and meta-analysis of 24 studies found small to medium improvements in cancer-related fatigue in women with breast cancer. A 2021 systematic review and meta-analysis of 26 studies (n=2069) found significant improvements in quality of life in women with breast cancer, including social, emotional, and functional well-being. Most effects have been assessed only in the short term; long-term effects are not well known. Low-intensity forms of yoga, specifically gentle hatha and restorative, are feasible, safe, and effective for treating sleep disruption, cancer-related fatigue, cognitive impairment, psychosocial distress, and musculoskeletal symptoms in cancer patients receiving chemotherapy and radiation and cancer survivors.

B. Hypertension

A 2019 systematic review and meta-analysis found that yoga had a modest but clinically relevant reduction in blood pressure (systolic blood pressure: −5.0 mm Hg; diastolic blood pressure: −3.9 mm Hg). The greatest benefits were seen when breathing techniques and meditation/mental relaxation were included. Yoga has been consistently superior to no treatment but has not been clearly superior to aerobic exercise. The efficacy of yoga in the secondary prevention of CAD is still under evaluation.

C. Low Back Pain

A 2020 systematic review of 18 trials with chronic low back pain concluded that there is low to moderate certainty evidence that yoga results in small to moderate improvements in pain at up to 7 months; it was not shown whether yoga was superior to physical therapy exercises for back pain. A systematic review and meta-analysis concluded that there was strong evidence for short-term and long-term benefit on pain, reduced back-specific disability, and increased global improvement and moderate evidence for a long-term benefit on back-specific disability. An additional RCT concluded that a 6-week yoga intervention is a cost-effective early treatment for low back pain. No serious adverse events occurred in any of these studies.

D. Chronic Obstructive Pulmonary Disease

A systematic review and meta-analysis of 11 RCTs of 586 COPD patients found that yoga training significantly improved forced expiratory volume in 1 second (FEV₁), 6-minute walking distance, and quality of life measures. This review suggests that yoga breathing technique can be an effective adjunct intervention for patients with COPD.