DEFINITION & EPIDEMIOLOGY
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:
RYT 200 (this is the minimum level of teacher training signifying that the teacher graduated from a Yoga Alliance-approved 200-hour training).
RYT 500 (this level signifies graduating from a 500-hour training plus having 100 hours of teaching experience).
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).
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.