Low back pain (LBP) is a prevalent clinical concern and symptom, which is defined as pain or discomfort in the area between the lower rib and the gluteal folds (1). The global population prevalence rate of LBP has reached 7.3% (2). The lifetime prevalence rate of LBP can be as high as 47% in low-income countries such as Africa (3). A systematic review shows that running can decrease the incidence of LBP and can serve as a protective factor for preventing the onset of LBP (4). The etiology of LBP is complex and not completely understood; neurological, bladder dysfunction, loss of anal sphincter tone, and saddle anesthesia are factors that can contribute to the onset of LBP (5). Clinicians can identify potential pathologies that resemble musculoskeletal conditions through the use of screening and differential diagnosis. More emphasis should be placed on patients with signs and symptoms that resemble severe pathology in the thoracolumbar region, such as LBP due to post-traumatic thoracolumbar fracture (6), and other potential non-musculoskeletal causes of LBP including LBP due to secondary peripheral arterial disease (7). Chronic low back pain (CLBP) is LBP lasting 3 months or longer. More than 70% of people experience CLBP at least once in their lifetime (8). CLBP can cause physical diseases and lead to anxiety and depression, thus decreasing the quality of life (9). CLBP has become a significant public health concern. The resulting inability to work, disability, and medical expenditure have imposed a substantial financial burden on individuals and society (10).

Presently available biomedical therapies for CLBP are expensive, have poor long-term efficacy, and may cause adverse side effects (11). Therefore, many patients with CLBP prefer alternative treatments. Recent practice guidelines from the American College of Physicians suggest that non-pharmacological therapeutic modalities can be considered if standard medical treatments fail to alleviate LBP (12). Exercise is strongly recommended as a non-pharmacological intervention because it can effectively relieve pain (13). Yoga has garnered widespread attention as a characteristic meditative movement therapy that integrates body and mind (14). Yoga originated in ancient India and has a history of over 4,000 years. Yoga comprises several key components, such as physical posture (asana), controlled breathing techniques (pranayama), relaxation, and meditation (dhyana) (15). The inherent nature of yoga is characterized as gentle and soothing. It can improve the strength of the back muscles and alleviate pain while promoting the extension, flexibility, and balance of the body tissue of the spinal vertebra (16). Yoga can improve physical functions. One study has shown that yoga can decrease anxiety and improve self-efficacy and pain acceptance (17). This is particularly helpful because CLBP occurs due to a complex interplay of biological, psychological, and social factors, and the availability of emotional support from practicing yoga can improve the confidence of the patients in overcoming the disease (18). Furthermore, the underlying mechanism of action of yoga is linked to contextual factors, which are the result of a combination of personal, disease-related, and environmental factors (19), where pain-induced contextual factors can be conceptualized as triggers of placebo and nocebo effects (20). Particularly in musculoskeletal disorder (MSK)-associated pain, the mood and expectations of the patient can affect MSK pain (21). Previous studies have shown that physiotherapy for MSK can effectively ameliorate pain when patients redirect their attention away from the disease compared with when patients focus on the pain (22).

Many clinical studies, systematic reviews (SRs), and reviews have reported the efficacy of yoga in the treatment of CLBP. However, adequate and unified data are not available. An overview of SRs can be performed to comprehensively collect and evaluate the relevant systematic evaluation of the treatment, etiology, diagnosis, and prognosis of the same disease or health problem. This can provide more robust, high-quality evidence for clinicians and promote their decision-making ability (23). In this study, we evaluated and objectively summarized the efficacy and safety of yoga in treating CLBP by overviewing SRs to provide clinicians with evidence of synthesis that can serve as a basis for decision-making.

This overview was performed according to the Cochrane Handbook for SRs of Interventions (24) and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (25).

The vast majority of patients with CLBP, a common MSK, complain of lumbosacral pain that lasts for an extended period. Moreover, the onset of the disease is insidious and not easily noticed by patients; thus, the disease puts a great burden on the mental and financial conditions of patients. The way a clinician approaches a patient with CBLP profoundly affects CLBP treatment because the patient may specifically remember negative inhibitory information and develop avoidance behavior and panic beliefs (21). Owing to the difficulty in determining CLBP pathogenesis, a clear pathological basis is unavailable for clinically available laboratory measures, and the subjective analysis of pain caused by the disease is common. Therefore, in the context of the modern biopsychosocial model of medicine, the American College of Physicians Guidelines for CLBP recommend a combination of physical and psychological treatments (12), and yoga meets this need.

Yoga, which originated in ancient India, is a form of physical and mental exercise that comprises meditative relaxation, breathing, and asanas. Meditation practice helps focus the mind and allows the practitioner to direct their awareness to breathing. Moreover, modern scientific research has shown that meditation can increase the levels of neurotransmitters, including melatonin and gamma-aminobutyric acid, and endorphins, thus playing a positive role in reducing mental stress and its effects in humans (44). Additionally, yoga asana practice can improve muscle strength, joint flexibility, and balance in patients with CLBP. Tilbrook et al. (45) found that after a 12-week yoga program, the back muscle function of adults with CLBP improved over 12 months, suggesting that yoga strengthened muscle stability and reduced low back pain by increasing hip and spinal flexibility. Thus, we searched for the published literature related to the SR of yoga in CLBP treatment to evaluate the effectiveness of yoga for managing CLBP and verify whether it is a supplementary and alternative treatment strategy for patients with CLBP.

We systematically evaluated the included studies using the AMSTAR-2 scale, PRISMA-2020 statement, and GRADE system. In terms of methodology, most critical factors were reported poorly because most studies lacked a presentation and description of the used preliminary research protocol and literature search, excluded reference lists, and failed to address sources of heterogeneity and risk of bias such as publication bias. Emphasizing the abovementioned factors can improve the methodological quality of SRs/MAs. In terms of reporting quality, the included SRs were generally of low reporting quality, primarily because of methodological flaws in reporting, especially regarding data processing and presentation. In terms of evidence quality, most SRs were characterized by inadequate or unreasonable randomization, blinding, and allocation concealment. Simultaneously, a significant risk of heterogeneity and homogeneity, mainly related to the small number of trials and the number of participants, as well as indicators observed in a single body of evidence, was present. Additionally, the repetition rate of the original RCT results extracted using the GROVE tool was very high, which might have resulted in some bias. Therefore, the careful handling and discussion of all aspects of a research design and its implementation are necessary. Moreover, higher-quality, large-sample, multi-center RCTs should be conducted to improve the homogeneity of evidence sources (46).

The present study showed that yoga exerted a certain therapeutic effect to improve pain and functional disability; however, the low-quality results reduced the credibility of the evidence. With respect to pain scores, most evidence pieces supported the efficacy of yoga in managing CLBP. Compared with non-exercise measures, yoga interventions significantly improved pain scores in patients with low back pain. Wieland et al. (36) showed a large pooled effect for yoga compared with non-exercise measures on pain scores, especially in the short term of 4–6 weeks (MD = −11.05, 95% CI = −14.22 to −7.88). However, this effect gradually decreased after 3 months (MD = −4.53, 95% CI = −6.61 to −2.46). Zhu et al. (34) showed no statistical significance regarding the long-term efficacy of yoga (MD = −0.52, 95% CI = −1.64 to 0.59). These results indicate that yoga probably exhibits better short-term efficacy than a non-exercise measure. Additionally, we found that compared with physical and exercise therapies, yoga did not exert remarkable effects, even though many results were statistically significant. Moreover, many MD values were less than the clinical minimum important difference. In this comparison, the pain improvement due to yoga was not considerable. Dennis et al. (33) distinguished passive exercises from active exercises. Compared with active exercises, yoga did not show statistical significance (MD = −0.78; 95% CI = −1.62 to 0.06), whereas compared with passive exercises, yoga showed significant results (MD = −0.74; 95% CI = −1.04 to −0.44) for CLBP management. Nevertheless, this difference decreased in follow-ups longer than 12 months (no statistical significance), suggesting a minor long-term pain improvement with yoga. In terms of improving functional disabilities, the study showed that yoga was advantageous in improving functional disability, which was more pronounced in a follow-up study by Dennis et al. (33), and Kang et al. (32) also found a significant advantage. However, Zhu et al. (34) found that compared with physical therapy, yoga showed no statistically significant results, suggesting that yoga might not be advantageous over physical therapy. Because the mentioned results have been pooled from a small number of studies, publication bias cannot be ruled out. In terms of improving the quality of life, yoga may not be effective compared with other controls, as evidenced by many non-significant results. With respect to a short- or long-term improvement in the quality of life, most evidence pieces (GRADE evidence from very low to moderate) showed that yoga had no significant advantage. These findings suggest that yoga may not have a noticeable therapeutic effect on improving the quality of life of patients with low back pain. However, we think that this inference may also be related to publication bias because these results are pooled from small-sample studies, and large-sample RCTs have not been conducted yet. Thus, future studies should verify this inference. Next, two studies (33, 36) assessed the safety of yoga for patients with low back pain using adverse events as the outcome. Wieland et al. (36) found that yoga was associated with a significantly increased risk of adverse events compared to non-exercise controls (RR = 4.76; 95% CI = 2.08–10.89); however, no statistical difference was observed when yoga intervention was compared with other exercises. Dennis et al. (33) showed no statistical difference in the incidence of adverse events between yoga and other conventional exercise groups, consistent with the Wieland et al. results. Therefore, we believe that yoga has the same safety profile as other exercise therapies; thus, it can be recommended as a supplementary exercise therapy for treating low back pain.

In conclusion, yoga appears to be an effective and safe non-pharmacological strategy for treating CLBP. Currently, it may exhibit better efficacy in improving pain and functional disability associated with CLBP. However, owing to the generally low quality and certainty of the evidence pooled from the included SRs, the present results should be interpreted cautiously. In addition, we found numerous non-significant results and low-quality evidence regarding yoga practice to improve the quality of life in patients with CLBP. Therefore, whether yoga is different from other exercise or non-exercise therapies in improving the quality of life remains unclear. Nevertheless, the evidence presented herein is mostly obtained from small-sample studies without verification and validation from large-sample MAs.

The original contributions presented in the study are included in the article/Supplementary material, further inquiries can be directed to the corresponding authors.

XZ: Conceptualization, Formal analysis, Methodology, Writing—original draft. TC: Conceptualization, Formal analysis, Methodology, Supervision, Writing—original draft. WH: Conceptualization, Data curation, Supervision, Validation. MS: Conceptualization, Formal analysis, Methodology, Supervision. YC: Conceptualization, Data curation, Supervision, Validation. SW: Data curation, Formal analysis. GZ: Data curation, Formal analysis, Methodology. MH: Data curation, Formal analysis, Methodology. MZ: Conceptualization, Data curation, Formal analysis. JY: Conceptualization, Data curation, Formal analysis. HY: Conceptualization, Data curation, Formal analysis. LZ: Data curation, Formal analysis. CZ: Data curation, Formal analysis. ZL: Funding acquisition, Writing—review & editing. XL: Funding acquisition, Writing—review & editing.