Low-back pain (LBP) is commonly defined by episodes of remission and recurrence, which have the potential to be debilitating for many patients. As many as 3 in 4 patients with resolved LBP will experience a recurrent episode within 1 year.1–3 Unsurprisingly, chronic LBP is one of the most frequent causes of lost workdays and poor quality of life, and the direct cost to the healthcare system related to its diagnosis and treatment has been estimated to be as high as $2.5 billion annually.2,4 The vast majority of these patients are managed nonoperatively, as the etiology of their symptoms is often multifactorial, of uncertain origin, or without clear operative pathology.5
The usual recommendations for nonoperative management of LBP include self-management (in the form of advice and education), nonprescription pain and antiinflammatory medications, exercise and physical therapy, and consideration for referral for psychological/cognitive behavioral therapy.3 There is equipoise as to whether one approach, or a combination of modalities, is most effective. As we further refine the indications for surgery, there is clearly a need for identification of other cost-effective, noninvasive treatment options for this condition. Yoga, a mind-body practice with historical roots in the Indian subcontinent, may be an excellent option to consider as nonoperative treatment for chronic LBP. Indeed, the most recent American College of Physicians guidelines on the treatment of LBP included yoga as a treatment option.6 Therefore, we believe that it is important for spine surgeons to be familiar with yoga, which is already widely practiced and is likely to be increasingly recommended to people with back pain.
Yoga Is a Popular Exercise and Therapeutic Modality in the United States
The popularity of yoga in the United States has surged over the past decade, increasing from 13 million users in 2007 to more than 35 million users in 2017.7,8 Notably, of the major complementary health approaches, yoga is now the most commonly utilized among respondents to the National Health Interview Survey.8 Moreover, a large proportion of respondents report using yoga for health reasons,9 and almost 20% indicate that the reason they participate in yoga classes is specifically for back pain.7,10
Numerous modern schools or styles of yoga exist (Table 1), most of which are forms of traditional Hatha yoga. All yoga styles may be characterized by the inclusion of breathing techniques (pranayamas), meditations (dhyanas), and physical poses (asanas; Fig. 1). Each style differs in terms of the balance of inclusion of spiritual and physical practices, with some styles focusing more exclusively on physical postures despite the historical focus of yoga on inner development.
Popular styles of yoga and brief descriptions
| Type of Yoga | Description |
|---|---|
| Hatha | Hatha yoga is the name describing the use of postures, breathing, chanting, and relaxation techniques meant to strengthen the internal musculature (bandhas). Most styles of yoga are subcategories of Hatha yoga. |
| Kundalini | Kundalini uses a variety of both slow and rapid breathing techniques, dynamic postures, static postures, and chanting, in its Sikh-oriented approach to yoga. |
| Vinyasa | Vinyasa yoga is a hybrid practice of yoga that has largely borrowed from several traditional Hindu yoga practices to create a flowing style of yoga. It is a popular style of yoga, although its detractors criticize the lack of attention to detail or safety of some of the sequencing. |
| Ashtanga | A rigorous and challenging form of yoga, Ashtanga yoga is similar to martial arts in its levels (or sequences) that can take many years to learn. The practice is adaptable but does contain some complicated positions. |
| Hot | Hot yoga is a practice involving 26 yoga postures and 2 breathing techniques that are done in sequence. The postures are typically performed in a room that is heated to 105°F. While the poses themselves are suitable for most people, the heat can be difficult for some. |
| Integral | Integral yoga was created by Swami Satchidananda, who famously chanted an opening prayer at Woodstock. It is very light and accessible, providing an easy approach to yoga. The classes include small amounts of mantra chanting, postures, and breathing and are largely geared toward creating a sense of inner peace. |
| Sivananda | Sivananda yoga is a traditionally Hindu form of yoga that includes chanting, breathing practices, postures, and relaxation. It is a set formula of 12 basic postures, 2 breathing practices, some preparatory exercises, and deep rest. |
| Yin | The postures in Yin yoga are held for several minutes at a time and are said to direct the attention of the postures toward the connective tissue. It is a very low-impact form of yoga and does not demand too much energetic output. |
| Iyengar | Iyengar yoga focuses on finding a healthy postural alignment in each pose through the use of props, anatomical instruction, and careful entry into the postures. It has a strong rehabilitative component to it. |
| Restorative | Restorative yoga is an approach aimed at downregulating the stress response through gentle postures with the use of props. It differs from Yin and Iyengar approaches in that the stated goal is to apply no effort while in the postures, which are to be held in such a way so that deep rest is achieved. It is helpful for people with psychological stress and physical limitations. |
Ashtanga yoga teacher and coauthor Eddie Stern in extended triangle pose (Utthita Trikonasana).
Challenges in Studying Yoga as a Therapeutic Intervention
When comparing studies that seek to determine the efficacy of yoga in the treatment of LBP, many considerations must be taken into account that influence the generalizability of their conclusions. These include, but are not limited to, the style of yoga under study (e.g., Iyengar vs Hatha vs Vinyasa), duration or intensity of the intervention, patient compliance, follow-up regimens, and elements of bias.
Unsurprisingly, the styles of yoga that have been studied in the context of LBP all include elements of physical poses in their practice. There is no literature available that offers a meaningful comparison of different types, doses, or regimens of yoga practice.3 Studies also vary based on which component of each individual style is studied. For example, Iyengar practice includes different postures and breathing, as well as relaxation and mental focus techniques, the utilization of which may vary depending on the study.12,20,27 This variability makes it difficult to assess which style or which components of the style are producing meaningful patient benefit.
In addition to the inherent differences in practice, patient compliance can vary greatly among these studies. Not all studies report compliance, or compliance is descriptive (e.g., “more” or “less”), but not quantified,13,31 while others report rates of 60%–70%.12,28 Duration and frequency of treatment and length of follow-up differ dramatically between studies.11–14,18–20,23,27–40 This variability belies the fact that there is no agreed on duration of treatment that provides a clinically meaningful result, as well as raises questions about the durability of the intervention.
Another major critique of these studies is the risk for multiple sources of bias (e.g., performance bias, detection bias, and response bias) due to the lack of blinding and self-assessed outcomes in the form of surveys.3,11,36,41 Since participation in the yoga arm of a study might require more buy-in and perseverance (e.g., compared with a medical intervention), the risk of attrition bias must also be considered. One study of dropout rates in randomized controlled trials (RCTs) on yoga interventions found that dropout was typically below 20% but could exceed 40% in some demographics.42
Possible Benefits of Yoga as It Relates to LBP
Although methodologically rigorous research remains in the early stages, most studies have reported positive effects of yoga interventions, and there is an abundance of both anecdotal and RCT evidence to suggest that it may have utility surpassing usual nonoperative care.3,7 Benefit is thought to be derived from changes in physiological, behavioral, and psychological factors, as well as from improvements in flexibility, strength, relaxation, and body awareness.3,11–15 There is evidence to suggest that yoga reduces oxidative stress and tissue inflammation, increases the release of certain neurotransmitters in the brain, and even results in brain remodeling that is correlated with decreased anxiety and increased pain tolerance.11,14–26 Long-term yoga practitioners also demonstrate significantly less cervical and lumbar degenerative disease on MRI compared with matched control groups.14,25
While studying the influence of yoga practice on LBP is challenging, there is evidence of variable certainty to suggest that there is a net positive effect in many domains.3 These range from self-reported measures of pain, discomfort, and disability to improved flexibility, mood, and pain tolerance. To quantify the effect of yoga practice on back pain, authors have used validated questionnaires to measure pain and disability. The visual analog scale (VAS), Oswestry Disability Index, Roland-Morris Disability Questionnaire, SF-36, and Pain Self-Efficacy Questionnaire are the most commonly employed and used in other studies to describe LBP.
When compared with nonexercise controls, there appears to be a mild positive effect of yoga on self-reported pain outcomes at early time points, although the durability of this effect is uncertain.3,12,20,27,30,38 The effect of yoga on overall functional status and self-reported clinical improvement, however, may be more durable.3,12,20,27,30,37–39
As more Americans seek out yoga as an adjunct or alternative to usual care for managing LBP, it is most important to understand how it compares with other types of exercise and physical activity. While the evidence is of variable certainty, given differences in interventions and inherent biases, one can conservatively posit that yoga is noninferior, at worst, and possibly more effective than nonyoga exercise interventions in relieving LBP and improving functional status.3,11,13,19,23,29,31,37,39,40 Interestingly, while studies demonstrate a positive correlation between yoga practice compliance and treatment effect, yoga as an intervention appears to be relatively dose independent.28,32,34 Additionally, it is important to note that yoga is not associated with any serious adverse events, and the risk of adverse events is not increased in comparison with nonyoga exercise.3
There are other secondary effects of yoga practice that are of relevance when counseling patients with LBP. Of particular interest to the public are effects on prescription pain medication use and factors relating to stress and sleep health. A number of studies have shown that a yoga intervention results in decreased pain medication use, without a requirement for long-term participation in a program.12,20,38,40 Others have demonstrated that yoga results in rapid improvements in stress perception and sleep quality and can result in a reduction in work absenteeism.24,29,43 Finally, from an economic perspective, evidence has suggested that yoga as an adjunctive treatment for LBP is cost-effective.35
Rationale for Further Study and Conclusions
Yoga has been practiced, in some form, by millions of people for centuries. In recent years, there has been increasing interest in yoga as a therapeutic intervention for multiple psychiatric and medical conditions, including back pain. It is a low-risk activity that can be pursued with little investment and can develop into a fully independent practice at home. Chronic LBP is a significant public health issue contributing to high healthcare expenditures, lost workdays, and opiate dependence. Although there are data to suggest that yoga has benefit in treating chronic LBP, well-designed studies are needed to validate this assertion. Many studies on the subject have suffered from lack of generalizability, heterogeneity in adherence to a treatment protocol, and lack of long-term follow-up.
Our institution has begun enrolling patients in a clinical trial with a defined yoga protocol treatment arm, comparing this with usual care in chronic LBP patients for whom surgery is not being offered (ClinicalTrials.gov identifier NCT04270617). The control arm will involve usual care: 6 weeks of physical therapy, nonsteroidal antiinflammatory drugs, and epidural steroid injections. The study arm will involve a yoga protocol devised by Eddie Stern, a renowned Ashtanga yoga practitioner, and can include nonsteroidal antiinflammatory drugs. The protocol has been designed to contain poses addressing core strength, but it is gentle enough for patients in pain. The protocol will be directed by a teacher initially, can be easily followed at home, and is only 18 minutes in duration. We plan for a 2-year follow-up period after enrolling 200 patients. This study is powered to test the primary hypothesis of improvement in VAS score at 6 months between the standardized yoga practice versus usual care groups. For this hypothesis, we expect a difference of 0.23 (SD 0.5) in the VAS scores between the usual care and the standard yoga practice groups. Using the Wilcoxon rank-sum test with a 2-sided type I error rate of 5% and a power of 80%, 80 subjects are required for each arm to detect the above difference. By incorporating a dropout rate at 20%, we plan to enroll 100 subjects for each study group (i.e., 200 in total). Although our study may not confirm yoga as a primary treatment option for chronic LBP, in light of the recent opioid crisis and the fact that only a small subset of patients benefit from surgery, there is a need for high-quality studies validating other safe and effective nonoperative treatment modalities for this condition.
Disclosures
The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
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