Yoga

The Yoga Sutras and their dating

The Yoga Sutras are a Sanskrit text attributed to Patañjali, transmitted together with an early commentary, and the specialist Philipp Maas calls the combined work the Pātañjalayogaśāstra. In his account it was composed in the late fourth or early fifth century CE, about 400 CE. He reasons from its references to Vijñānavāda Buddhism and from quotations in later works that set the latest date in the second half of the fifth century. This is one specialist's reconstruction, and the sources reviewed do not survey other scholars' proposals.

Haṭha yoga texts

Practices centered on the body are documented later than the Sutras. Péter-Dániel Szántó and James Mallinson, editing the Amṛtasiddhi and its Tibetan counterpart, argue that haṭha yoga arose in an eclectic tantric Buddhist milieu probably active in the second half of the eleventh century CE. A University of London research project dates the Haṭhapradīpikā, a foundational haṭha text, to the early fifteenth century under the author Svātmārāma, with the oldest manuscript used in its edition dated 1496 CE among more than 200 manuscripts.

Modern postural yoga

A Wellcome Collection article states that transnational yoga systems such as ashtanga, Iyengar and Sivananda center on posture practice and blend older yogic practices, South Asian physical culture and modern Western exercise. It identifies Tirumalai Krishnamacharya in 1930s India, working at the invitation of the Maharajah of Mysore, as the key figure. His students B.K.S. Iyengar and Pattabhi Jois founded two global styles, and Indra Devi is credited with popularizing yoga in the United States. Jivamukti (1980s) and power yoga (1990s) are listed as later Western schools.

Book-length scholarship on modern postural yoga, including Mark Singleton's Yoga Body and Elizabeth De Michelis's work, was not freely readable and is not cited here. The article summarized above is a short museum essay, so details of dates and influences should be checked against that scholarship. Style-level history is covered on the Yoga Styles page.

Yoga, asana and pranayama

The US National Center for Complementary and Integrative Health (NCCIH) describes yoga as a practice rooted in Indian philosophy that began as a spiritual practice and became popular for physical and mental well-being. It says the form common in the United States typically emphasizes physical postures (asanas), breathing techniques (pranayama) and meditation. In Maas's account of the Sutras, posture is one of eight means of yoga, so the modern equation of yoga with posture practice reflects the twentieth-century developments described above. The sources reviewed do not give an etymology of the word yoga.

The eight limbs

Maas lists the eight means of yoga in the Sutras as commitments, obligations, posture, breath control, retraction of the senses, fixation, meditation and absorption. The Sanskrit word for this set is aṣṭāṅga, often rendered in English as the eight limbs. The modern style named ashtanga yoga, created by Jois, is a separate subject from this eightfold scheme and is covered on the Yoga Styles page.

One word, many interventions

Trials and reviews use the word yoga for varied programs. The Cochrane review of low back pain found that most trials used Iyengar, hatha or viniyoga forms, while the Cochrane asthma review found that five trials tested yoga breathing alone and the others combined breathing, posture and meditation. NCCIH notes that yoga styles vary widely and that differences in study designs make research hard to evaluate. Findings therefore apply to the program, population and condition studied, not to yoga in general.

Typical elements of a modern class

According to NCCIH, practice in the United States generally combines physical postures, breathing techniques and meditation, with emphasis varying by style and teacher. Styles differ in pace, how long poses are held, and whether props or heat are used. Pranayama, nidra, kundalini and meditation are treated on their own pages, and the sources reviewed here do not give a standard class length or sequence.

Programs as delivered in trials

In the 21 trials in the Cochrane low back pain review, participants were recruited from clinical and community settings and were mostly women in their 40s or 50s. In the Cochrane asthma review, yoga interventions lasted from two weeks to 54 months, in most trials no more than six months. Control groups included waiting lists, usual care, education, physical therapy and other exercise. Research programs are often more structured than a typical community class.

Instruction and adaptation

NCCIH advises practicing with a qualified instructor, asking about the instructor's training and experience, and telling both the instructor and a health care provider about any health condition. It lists knee or hip injuries, lumbar spine disease, severe high blood pressure, balance problems and glaucoma as conditions that may call for modified practice. How classes are adapted in practice is not described in the sources reviewed.

Uses described by reviewers and NCCIH

NCCIH lists low back pain, neck pain, headaches and knee osteoarthritis among the conditions for which yoga has been studied. Review authors describe yoga as a complementary therapy commonly recommended for impairments after breast cancer, as one of the most commonly used mind-body interventions for depression, and as a popular approach to improving emotional health. Asthma reviewers describe it as a holistic therapy with potential to relieve physical and psychological suffering. These are the authors' framings of why trials were run, not results.

Spiritual and general well-being aims

NCCIH notes that yoga began as a spiritual practice, and Maas's account of the Sutras places the discipline in a framework of ethical commitments, meditation and absorption. Many practitioners and traditions treat yoga as a path with spiritual aims, which research outcomes such as pain scores do not measure. The sources reviewed do not document why people take up yoga in everyday life, so this page does not describe motivations beyond those stated by researchers.

Cochrane review: chronic low back pain

A 2022 Cochrane review (searched to August 2021) included 21 trials with 2,223 adults with chronic non-specific low back pain. All trials were at high risk of performance and detection bias because participants and providers could not be blinded and outcomes were self-assessed, and none used sham yoga. Compared with no exercise at three months, yoga produced a small improvement in back-specific function (low certainty; mean difference -1.69 on a 0 to 24 scale, where the minimal clinically important difference is 5) and in pain (moderate certainty; -4.53 on a 0 to 100 scale, where the difference is 15). Both were called clinically unimportant.

Against back-focused exercise there was probably little or no difference in function at three months (moderate certainty), and the pain evidence was very low certainty. The authors concluded that choosing yoga over other exercise may depend on availability, cost and preference.

Cochrane reviews: asthma and breast cancer

A 2016 Cochrane review of yoga for asthma (searched to July 2015) included 15 trials with 1,048 mostly adult participants with mild to moderate asthma; one trial had low risk of bias throughout. Yoga probably improved asthma quality of life (5 trials; mean difference 0.57 on a 7-point scale, 95% confidence interval 0.37 to 0.77) and symptoms (3 trials; standardized mean difference 0.37). Change in forced expiratory volume in one second was not statistically significant.

A 2017 Cochrane review of yoga in women with breast cancer (searched to January 2016) included 24 studies (2,166 participants). Compared with no therapy, moderate-quality evidence showed short-term improvements in health-related quality of life (standardized mean difference 0.22), fatigue (-0.48; 11 studies) and sleep disturbance (-0.25). Depression and anxiety did not clearly improve, and two studies found no medium-term effect on fatigue or quality of life. Evidence against exercise controls was very low quality, and the findings should not be carried to other cancers.

Meta-analyses: depression and anxiety

A 2013 meta-analysis (searched to January 2013) of 12 trials with 619 participants found moderate evidence for short-term lower depression severity with yoga than with usual care (standardized mean difference -0.69, 95% confidence interval -0.99 to -0.39), with limited evidence against relaxation and exercise. Only three trials had low risk of bias and no trial reported safety data. A 2018 meta-analysis of eight trials (319 participants) found small short-term reductions in anxiety compared with no treatment (-0.43), but no effect in people with a formally diagnosed anxiety disorder.

NCCIH summary and gaps

NCCIH reports a slight benefit for low back pain, a 2019 review of 10 studies finding less neck pain and disability, preliminary evidence for tension headaches, inconclusive migraine results, and knee osteoarthritis research of limited quality. No Cochrane review of yoga for depression, or for fatigue across cancer types, was found. Evidence is limited by unblinded designs, self-reported outcomes and short follow-up.

How often injuries and adverse events are reported

A systematic review of nine observational studies (9,129 practitioners and 9,903 non-practitioners) reported adverse events in 22.7% of people during a yoga class, a 12-month prevalence of 4.6% and serious events in 1.9%. Musculoskeletal problems were most common, mainly sprains and strains. Practitioners had a comparable risk of falls but a higher risk of meniscus injury (odds ratio 1.72). The authors judged most events mild and transient. Across 94 randomized trials (8,430 participants), rates matched usual care and exercise but exceeded psychological or educational comparators.

In the Cochrane low back pain review, low-certainty evidence from eight trials showed more adverse events, mainly increased back pain, with yoga than with no exercise at six to 12 months (risk ratio 4.76; 43 per 1,000 against 9 per 1,000), and similar rates to other exercise. The asthma and breast cancer reviews found no serious adverse events but said safety data were limited or inadequately reported.

Postures, neck and eyes

A systematic review of 35 case reports and 2 case series (76 cases, searched to February 2013) linked adverse events most often to headstand (10 cases), shoulder stand (3), lotus position variations (3) and forceful breathing (3). Musculoskeletal injuries made up 27 cases, nervous system events 14 and eye events 9; the nervous system group included vertebral artery occlusion after head hyperrotation or neck hyperextension. Ten cases had pre-existing conditions, mainly glaucoma and osteopenia. Outcomes included full recovery in 15 cases and one death. The authors state that case reports cannot estimate frequency.

NCCIH likewise advises beginners to avoid headstands, shoulder stands, lotus position and forceful breathing, states that serious injuries are rare, and reports higher emergency department injury rates in people aged 65 and older. It also names learning without supervision as associated with higher risk.

Pregnancy, heat and existing conditions

NCCIH advises pregnant people to have a health care provider evaluate them first, to avoid hot yoga, and to avoid poses requiring long periods of stillness or lying on the back. It says hot yoga carries special risks of overheating and dehydration. Conditions that may need modified practice include knee or hip injury, lumbar spine disease, severe high blood pressure, balance problems and glaucoma. The reviews above do not report on pregnancy, so these cautions rest on NCCIH's guidance.

The authors of the 2017 epidemiological review advise that people with serious acute or chronic illness seek medical advice before practicing. NCCIH says not to use yoga to postpone seeing a health care provider about a medical problem. Yoga is not a replacement for assessment or prescribed treatment.

Instructors and training

NCCIH advises asking an instructor about training and experience. No statutory regulation or national training standard for yoga teachers was found in the sources reviewed, which do not cover individual countries, and teacher credentials are covered on the Yoga Styles page.