The word yoga originates from “yuj” meaning to yoke, referring to the discipline of aligning the mind and body for spiritual goals. Yoga practices aim at calming down the agitations of the mind through physical postures with awareness (asanas), breath regulation (pranayama), meditation (dhyana), chantings (mantras), lifestyle changes, and spiritual beliefs. Yoga has metamorphosed as yoga therapy inculcating different yogic techniques for alleviating a spectrum of physical and psychological complaints.
Contemporary yoga has undergone a significant evolution from the traditional style by trying to fit in the various needs of practitioners. Transition in terms of quality of research in yoga has become the need of the hour. The earliest scientific literature from PubMed databases is from 1948. From 1948 to 2021, a total of 6628 articles were published in PubMed with the term “yoga,” and 75.9% of these researches have been published in the last decade. There are multiple reasons to substantiate this recent exponential increase in yoga publications: (1) its popularity as a low-cost, non-pharmacological health promotion and stress management tool, (2) global shift toward integrative approaches in medicine and focus on prevention, (3) global interest in using yoga as a tool to connect people, and (4) rising support from international and national research agencies and scholarly interest.
Considering the spurt of yoga research in the past decade, the need to tread cautiously in the selection of intervention is imperative. According to a PubMed search conducted by the researchers, 52 yoga styles were practiced in 306 randomized controlled trials (RCTs), out of which the most commonly used yoga styles were Hatha Yoga, Iyengar Yoga, and Integrated Approach of Yoga Therapy (IAYT). There is a challenge of comparing yoga studies. Since most of the studies in yoga have shown positive results, it is difficult to conclude which style of yoga is more efficacious. These concerns can be overcome by using common protocols of yoga, standardization of the method of its application, and transparency in reporting.
A yoga module is commonly understood as a set of yogic practices incorporated synergistically within a specified time to achieve a goal. The authors differ in their views for developing and validating yoga modules. Yoga module development usually follows a process which starts with the search in scientific and traditional literature to identify the appropriate practices. Opinion and consensus from experts about these practices help in validation. The Delphi process of iteration or Lawshe's content validity ratio has often been used to validate the developed yoga module. The feasibility of the module is tested to assert its practicability. A systematic process of yoga module development can help in determining the specific components of yoga and its validity, thereby allowing replicability in yoga research. However, not all trials report the details of the yoga interventions used.
To our knowledge, no other studies have systematically reviewed the published literature on the development of different yoga modules. One study described the guidelines for developing an RCT of yoga; this study, however, does not focus on the validation procedure for yoga modules. Having a standardized approach of developing yoga modules can be helpful for researchers and stakeholders to assert the quality of trials. The aim of the current study is to evaluate the development and validation processes undertaken by different researchers and propose a methodology for undertaking similar exercises for the future.
- Yoga module development – The process of newly constructing a yoga module from various reliable sources such as published studies or ancient texts intended to manage clinical/nonclinical conditions
- Feasibility study – Study done to evaluate the practicality of the proposed yoga module
- Stakeholders – Individuals who are engaged in the delivery of yoga practices or impacted by the yoga practices. These include patients, clinicians, and policymakers
- Validation – Seeking the opinion of experts in the relevant field and arriving at a consensus on whether the yoga module developed intends to fulfill its objective
- Yoga module – A list of yoga practices encompassing vital components such as asana and pranayama tailored for the management of specific clinical/nonclinical conditions. The term yoga protocol is also used since it has the connotation of the process of implementing the yoga module itself.
Methods and Data Extraction
The Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines and recommendations of the Cochrane collaboration provided the basis for this review study [Figure 1]. The compilation of the research articles was performed by three independent researchers (N. K., A. T., and A. R.). PubMed, SCOPUS, and Web of Science (WOS) were searched for English language articles published till December 2021. Those scholarly articles with full text regarding either development and/or validation of the yoga modules were considered for the systematic review. The keywords and Boolean operators used for the review were (validation OR development OR design) AND (yoga OR mind-body) AND (module OR protocol OR program). References of articles were also cross-checked from the selected articles to obtain additional related articles. There were no restrictions for the articles that were considered; controlled or uncontrolled trials, qualitative or quantitative studies, feasibility, pilot studies, and other clinical trials were included. Those articles which only mentioned the practices without elaboration on the selection method for the practices along with their validation were excluded. The study has been registered (CRD42022307249) under the International Prospective Register of Systematic Reviews (PROSPERO).
Based on the existing literature and interviews with yoga research experts, a list of 23 items was finalized [Table 1]. The authors of this article created a rating scale of low, medium, and high quality based on a 23-item checklist to assess the quality of each article [Appendix 1]. Each item carried a score of 1 if mentioned in the article and 0 if not included. The interval scoring range is given in Table 2. Two of the authors (A. R and N. K) carried out the scoring for the selected articles and A. T. clarified any discrepancy.
Out of the 3671 articles that were reviewed from SCOPUS, WOS, and PubMed, 2339 duplicate articles were removed. Two thousand one hundred and twenty-seven articles were excluded based on the inclusion and exclusion criteria. The full text of the 212 articles was screened leaving us with 59 articles eligible for our study, out of which 22 articles were excluded, and from that, further four articles were excluded due to inability to access full-text articles despite contacting the study authors. Finally, 37 articles remained for this exercise.
For the initial phase of module development, 32 articles conducted a scientific review and 27 also carried out a review of traditional literature. Ten articles consulted experts at the developmental stage of the yoga module. All the interventions had different practices of yoga, and one did not give clear details of the practices adopted in the module. Twelve articles mentioned that depending on the patient's conditions, practices can be modified. The duration of the yoga module ranged between 12 min and 90 min averaging to about 50 min per session. The number of sessions ranged between 1 and 5 sessions per week wherein the complete intervention generally lasted between 5 days and 3 months. The average duration of therapy was 7 weeks, while three articles omitted information concerning the dosage and frequency.
Of the 37 articles, 25 were from India, 7 from the U. S. A., 2 from the U. K., and one each from Japan, Taiwan, and Germany, respectively. Twenty-eight articles reported the validation of the yoga module. Twenty articles reported the adverse effect and safety of the module. Twenty-five articles mentioned the expert's eligibility, out of which 18 articles noted the diversity of the experts in terms of yoga background, profession, and geography. The number of experts validating a module ranged between 5 and 41. Seventeen articles provided a detailed list of items given to the experts. Fourteen studies also included stakeholders for validation. Twenty-eight studies completed the content validity and seven had qualitative input from experts. Seven studies included case vignettes as a part of validation. Twenty-one studies had applied the modifications suggested by experts where appropriate. Fourteen modules also facilitated home practice. Eighteen studies recommended the need for a qualified instructor.
Nineteen studies tested the feasibility of the module. The sample size ranged from 5 to 90 participants with varied study designs such as RCT and single-armed pilot studies. Feedback of the participants about the module was taken by 19 studies. Seventeen studies assessed outcome results in the feasibility phase. Seven studies measured the intervention fidelity. Out of the 37 studies, the highest score for quality of study as per the 23-item item checklist is 22 and the lowest score being 5. The researchers ranked the articles into three categories: low quality (0–7), medium (8–16), and high (17–23). Only three articles were rated as “low,” 25 articles rated as medium quality, and 8 articles rated as high quality.
This is the first systematic review focusing on yoga module development and validation process as per the researchers' knowledge which has led to the formulation of themes and subthemes [Figure 2].
The researchers found that the majority of studies in yoga were conducted in India and the U. S. A, out of which more than half are primarily associated with two prominent centers in India which are working in the area of yoga therapy research. In the majority of studies, researchers overlooked the following: the stakeholders' role during the developmental and validation stage; the use of clinical vignettes; safety and adverse effect of the module; modifications as per experts' comments; listing the detailed items given to the expert; intervention fidelity; and mentioning any outcome domains and qualitative inputs. Hence, most of the studies did not qualify for a rating of “high quality.” Different development and validation modalities were investigated and the most commonly used development method was literature review, while for validation, experts' scoring on the Likert scale was frequently used. For diseases such as diabetes mellitus, Parkinson's disease, cardiovascular diseases, cancer, and obesity, there were more than one module development studies. The present study recommends that in such cases, the researcher needs to mention what is lacking in the existing module and the rationale why a new module should be validated. In case the rationale for developing a new module is not robust, practices from the existing module can be adapted as required. Future standard reporting guidelines may incorporate this aspect.
In all the studies, a literature review was initially done to develop the yoga module. Most studies focused on scientific literature review only. However, contributions from traditional texts are equally important in such an exercise and may be even more authentic. There is a need to standardize the exhaustiveness of the literature search and the method of getting the relevant information.
Moreover, this review brings our attention to different yoga styles such as IAYT, Generic Yoga-based Intervention, Yoga-based Interventions, Yoga Therapy, Yoga Skills Training, Vinyasa Yoga, Iyengar Yoga, Silver Yoga, and Hatha Yoga. Each of these yoga schools has a common foundation of asana, pranayama, relaxation, and meditation with variations in the sequences and duration. A generic yoga concept based on traditional texts can be used to promote easier replication in the clinical context.
Concerning the duration and frequency of the practices, more information on the optimum dosage of yoga intervention is desirable. The duration of a yoga session as per the convenience/tolerance of the patients as mentioned in a few studies is a safer option to facilitate its application. The methodology of module implementation should ideally be mentioned by the module developers. For example, Thulasi et al. have developed a three-step yoga program based on the difficulty levels of the practices. Only the first part of the module was tested for its feasibility. We recommend having different levels of yoga modules, especially in the case of high-risk clinical conditions.
Few articles reported modifications of the newly developed yoga module as per participants' convenience along with flexibility in timings to increase their adherence. Should consideration of adherence be a part of module development? We recommend yoga module developers to consider adherence while developing the module. One study mentioned the flexibility in the structure of yoga modules based on the ease of learning of participants. Any yoga module made for the participants must include the flexibility of the yoga components. It balances participants' ability to adopt it conveniently without compromising the quality of practices. Yoga module developers also need to consider developing the modules in such a way that can help participants adapt from simpler practices to difficult modes to maximize benefits. The safety of the participants can be ensured by including graded yoga modules, especially for high-risk clinical conditions. This could also be invariably achieved by ensuring the presence of a trained instructor in the initial phases of intervention before recommending home practices. Some studies included expert consultation at the developmental stage. This can be useful to get precise inputs on the practices. Since these yoga modules also involve medical conditions, there is a need to adapt the practices as per the demand/condition of the patient; this justifies the yoga practitioners' and clinicians' viewpoints.
Around 75% of the studies carried out the content validity using expert judgment. The process for expert selection was not detailed, but some articles clarified the eligibility of the experts and the school of yoga they belong to. Experts can be selected based on their knowledge of the topic or their work experience. Most Delphi studies involve between 11 and 50 experts. Approximately 48% of studies have mentioned the qualification of the experts and the years of experience. The qualification varied from “certified yoga instructor” to “Doctor in Philosophy in yoga” with a minimum experience of 5 years. The experts play a key role in validation by providing valuable inputs. We recommend that the selection of experts should be diversified with respect to the yoga school, condition of disease/disorder, and professional experience in the same field to avoid research bias, and conflicts of interest. For example, in the case of yoga module development for substance use disorder, since there are studies exploring different schools of yoga, it would be warranted to include experts belonging to varied schools such as IAYT, Hatha Yoga, Iyengar Yoga, Sudharshan Kriya Yoga, Kundalini Yoga, and Ashtanga Yoga along with experts from the medical background who are specialized in the field of substance use disorders.
The validation used Delphi methods, group discussion, interview, Likert scale, and content validity method. At the validation stage, some articles also included feedback from patients suffering from the concerned disease and yoga module deliverers such as physical trainers, social workers, and other individuals who may provide valuable information regarding acceptability, feasibility, and delivery of the yoga practices. The researchers believe that such practices help in strengthening the validation process. Only 18.9% of studies included case vignettes. Clinical case vignettes give a comprehensive report of the patient's history, specific symptoms, and other important information related to treatment. Case vignettes are an essential part of the module development as it can help the researchers get clarity on the disease concerned.
Close to 59% of studies mentioned the changes made after the expert's input. Forty-six percent of studies mentioned the details of items sent to the experts and the final items selected after expert validation. Access to the initial list of items can help other researchers get clarity on the type of practices that need to be avoided in certain diseases. Hence, it is recommended that an initial list of practices should be provided. The qualification of the instructor is another important factor during yoga therapy. The instructor should have required training in delivering yoga practices for the concerned condition and must be reported.
Out of 37 studies, only 18.9% of studies evaluated the intervention fidelity by using yoga posture self-efficacy questionnaires, checklists, or the yoga performance assessment tool. Use of such tools to evaluate the accuracy of the intended practices can be considered an essential part of the feasibility process of the module. During the feasibility testing phase, it is necessary to get feedback from the participant. This clarifies whether the yoga module is beneficial and whether any changes are required in the intensity, sequence, and dosage of practices as per the yoga module. Only around half of the studies (51.3%) took suggestions from the participants. Only 45.9% of the studies reported the outcomes by using appropriate assessment tools. These researchers did not limit themselves to checking the feasibility of the yoga module but also assessed whether the practices prescribed worked on bringing the stipulated changes in the end users.
Assessing the safety of the yogic practices must be considered mandatory by the module developer during the development, validation, and feasibility phases to avoid any injury. Any adverse effect observed by the researcher and participants needs to be reported to help contribute to the future development of the module. These findings point out that a combination of safety, doability of the practices, and adherence are key points to be considered for any yoga module development.
Several of the published yoga module validation studies had methodological limitations. The most common among them were: (1) Small number of experts, (2) lack of module validation and/or feasibility testing, (3) lack of information on the contents discussed with experts and diversity of experts, (4) lack of involvement of stakeholders for module validation, (5) lack of case vignette, (5) use of group discussion among experts, (6) modification of the practices as per the patient's current state and time, and (7) assessing the intervention fidelity.
Limitation and future recommendation
The search was limited to English language only. Thus, the possibility of missing some studies could not be ruled out. As for future directions, the authors recommend having a strong rationale for the selection of practices with support from experts along with empirical evidence. This can be achieved by citing studies which emphasize the relation between specific practices with the clinical, biomechanical, and psychophysiological mechanisms and outcomes. Module development can further gain rigor by applying qualitative discussions with experts rather than focusing solely on statistical methods. Moreover, considering the nature of the participants following the yoga module, there is a need for customization of the selected practices to ensure adherence. Future research can explore standardized methods of adapting existing yoga modules to suit participant requirements. Finally, the online adaptation of developed yoga modules needs to be duly considered, especially in the present context where there is a growing demand for tele-yoga.
The findings of this systematic review have shed some light on the scarcity of validated yoga modules in comparison to the growing number of yoga intervention studies published in recent years. We also observed that most of the published studies have methodological limitations. The authors recommend that yoga studies use developmental strategies as mentioned in this study before testing them for efficacy.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
The authors would like to appreciate Dr. Rajesh S. K, Dr. Nishitha Jasti, and Kiriti Bhushan for their inputs which have helped shape up the study to its present form.
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