Are There Benefits from Teaching Yoga at Schools? A Systematic Review of Randomized Control Trials of Yoga-Based Interventions

Table 2

PRISMA 2009 checklist.

Section/topic	#	Checklist item	Reported on page #
Title
Title	1	Are There Benefits from Teaching Yoga at Schools? A Systematic Review of Randomized Control Trials of Yoga-Based Interventions.	1
Abstract
Structured summary	2	Background. Yoga is a holistic system of varied mind-body practices that can be used to improve mental and physical health. Due to the well-known restorative effects of yoga on mental health, it has been utilized in a variety of contexts and situations beyond the standard therapy practice. Educators and schools in particular are looking to include yoga as a cost-effective, evidence-based component of urgently needed wellness programs for their students. Objectives. The primary goal of this study was to systematically examine the available literature for yoga interventions exclusively in school settings. The objective of this report was to explore the evidence of yoga-based interventions on academic, cognitive, and psychosocial benefits. Methods. Studies were identified by searching PubMed, PsycInfo, Embase, ISI, and the Cochrane Library. An extensive search was conducted for studies published between 1980 and October 31, 2014, using the following terms or key words, yoga, school, education, and children, alone and in combination with additional terms such as program, intervention, and yoga-based. Results and Conclusions. Forty-eight studies were identified and nine randomized control trials met criteria for inclusion in this review. Although most of the studies were classified as 2b, according to AHRQ evidence level criteria, which means low quality randomized control trials, this review suggests beneficial effects of yoga-based interventions at school on both psychological and cognitive functions. Effect size was found for mood indicators, tension and anxiety in the POMS scale, self-esteem, and memory. Future research requires greater standardization and must deal with the problem of appropriateness: what type of yoga-based intervention is most suitable for children and at what frequency and duration and observed variables.	1
Introduction
Rationale	3	Yoga is a holistic system of varied mind-body practices that can be used to improve mental and physical health. Due to the well-known restorative effects of yoga on mental health, it has been utilized in a variety of contexts and situations beyond the standard therapy practice. Educators and schools in particular are looking to include yoga as a cost-effective, evidence-based component of urgently needed wellness programs for their students. However, there is no critically appraised evidence such as systematic reviews on potential benefits of yoga-based interventions in school settings.	2
Objectives	4	The objective of this report was to review methodological quality among selected studies, exploring the evidence of yoga-based interventions regarding academic, cognitive, and psychosocial benefits, and to contribute to the study of low-cost, health-focused alternative programs for children and adolescents in school settings.	2
Methods
Eligibility criteria	5	Peer-reviewed, published manuscripts were considered. Studies were selected if (1) they included a yoga or yoga-based intervention, (2) the intervention was restricted to school settings (integrated into the school schedule or after class), (3) they included children and adolescents (ages 5–18), (4) they included an evaluation of anxiety, depression, stress, or other psychological measures such as mood indicators, self-esteem, confidence, and quality of life at both preintervention and postintervention, (5) they included the assessment of academic or cognitive performance as a consequence of the yoga intervention (pre- and postintervention), (6) the research designs were pilot studies, quasi-experimental designs, or randomized designs and included control groups with no interventions or an active control (comparative intervention), and (7) they were written in English. Exclusion criteria comprised (1) studies that utilized only meditation or relaxation techniques without the physical components such as postures (asana) or controlled breathing (pranayama) (MBSR based programs usually have yoga as part of the practice, but only MBSR studies in which yoga is highlighted or is the main component of the program were included in this review, whose intention is to cover primarily yoga), (2) yoga-based programs for children with learning disabilities or any diagnosed mental disorder, and (3) dissertations and conference presentations.	5
Information sources	6	Literature searches were conducted in PubMed, PsycInfo, Embase, ISI, and the Cochrane Library (1980–2014). An extensive search was conducted for studies published between 1980 and October 31, 2014, using the following terms or key words, yoga, school, education, and children, alone and in combination with additional terms such as program, intervention, and yoga-based. Ongoing registered clinical trials were not searched. The details for the full search strategy were listed in a flow diagram, as shown in Figure 1.	5
Search	7	PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library	5
Study selection	8	Four authors conducted the literature searching (C. Ferreira-Vorkapic, M. Marchioro, and S. Telles) and study selection (C. Ferreira-Vorkapic, M. Marchioro, and E. Kozasa).	5
Data collection process	9	Authors (C. Ferreira-Vorkapic, M. Marchioro, S. Telles, and E. Kozasa) screened abstracts to identify articles that meet inclusion criteria. Potential articles were then evaluated for inclusion. To conduct the study, all data was collected and evaluated in terms of selection criteria, procedure, participants, intervention, methodology, assessment tools, and outcomes. Follow-up and results were also assessed. The review has been prepared using preferred reporting criteria for systematic review guidelines (PRISMA). J. M. Feitoza has performed all the statistics (effect size). For the effect size calculation, the means and standard deviations (postintervention) from experimental and control groups were obtained directly from the studies.	5
Data items	10	Yoga, school, education, and children.	5
Risk of bias in individual studies	11	After the first appraisal, another examiner (J. Simões) evaluated the selected RCTs and a kappa coefficient was calculated in order to estimate reliability of data collection methods. The observed kappa score of suggests great consistency of agreement between investigators.	6
Effect size calculation	12	The comparison between experimental conditions was carried out after the analysis of the pooled effect size by the generic inverse variance method (random effect model) through standardized mean difference and Hedges’ g. Ninety-five percent confidence intervals were computed for all variables. Two studies [19, 26] were excluded from the effect size analysis due to insufficient data (mean values not provided). The analysis of the effect size of specific measures could only be performed on studies that observed the same variables such as mood, tension and anxiety [20, 23], self-esteem [23, 27], and memory [28, 29] when comparing the yoga to control groups.	6
Summary measures	13	The quality and reliability of the randomized control trials (RCTs) were evaluated according to the evidence levels recommended by the Oxford Center for Evidence-Based Medicine (AHRQ, 2002). The items included study question, study population, randomization, blinding, interventions, outcomes, statistical analysis, results, discussion, and funding source. The quality of all the included trials was categorized into levels of evidence varying from 1 to 5, according to low, unclear, or high risk of bias. The quality and reliability of the randomized control trials (RCTs) were evaluated according to the evidence levels recommended by the Oxford Center for Evidence-Based Medicine. Table 1 shows the classification of scientific evidence in systematic literature reviews	6
Results
Study selection	14	A flow chart depicted the search process and study selection (Figure 1). Of the 48 studies identified, 9 randomized control trials met criteria for inclusion in this review. Generally, the RCTs had low AHRQ evidence scores, with most studies receiving a score of 2b due to the lack of blindness and follow-up, reflecting the regular quality of reporting in these studies. All results and conditions of the studies are summarized in Table 3.	6
Study characteristics	15	The methodological quality of most included trials was generally reduced. The details are as shown in Table 3. The randomized allocation of participants was mentioned in all trials. Blinding information, however, was insufficient due to the nature of the study (in yoga trials practitioner blinding is impossible). Interventions included yoga or yoga-based programs conducted exclusively in school settings for children ranging from 7 to 17 years. Comparison groups included physical education, Ayurvedic treatment, and control. Cognitive and psychological functions were assessed and the total treatment duration ranged from 8 to 18 weeks.	6
Risk of bias within studies	16	The number of trials was too small to conduct any sufficient additional analysis of publication bias.	6
Effect size results	17	After an overall effect size calculation of each study (except for Ramadoss and Bose, 2010 [19], and White, 2012 [26]), the effect sizes obtained from similar measures were grouped together: mood, tension, anxiety, self-esteem, and memory. Figure 2 shows the forest plot of the general effect size in the selected studies. The general plot shows divided results with half of the studies favoring yoga and the other half favoring control. value for overall effect is not significant (), but this is probably due to heterogeneity of the variables.; Effect size from mood state indicators (POMS) was calculated from Khalsa et al., 2012 [23], and Noggle et al., 2012 [20]. Results indicate that the yoga group showed significantly better scores in the postintervention condition () (Figure 3). The same scale shows a second significant effect for the subitems tension and anxiety also after the yoga practice () (Figure 4).; A third comparison was carried out for the variable self-esteem [23, 27]. Results show greater self-esteem perception in the postintervention condition for the yoga group () (Figure 5).; Effect size for memory was also analyzed in Sarokte and Rao 2013, [28] and Verma et al., 2014 [29]. Both studies utilized memory assessment tools, but Sarokte and Rao 2013, [28] used two different instruments. The results show increased memory performance for the yoga group () (Figure 6).	7
Synthesis of results	18	Regarding the effects of yoga on psychological well-being, of the six studies, three of them support the benefits of yoga or yoga-based programs for children in school settings. Khalsa et al. [23] observed that yoga participants showed statistically significant differences over time relative to controls on measures of anger control and fatigue/inertia. Noggle et al. [20] also observed preventive benefits in psychosocial well-being (anxiety and negative affect) for students enrolled in a yoga program. In Ramadoss and Bose [19], only the yoga group demonstrated a slight decrease in stress while maintaining self-control. In contrast, Haden et al., 2014 [30] and White [26] observed a significant increase in perceived stress in the yoga group compared to the physical education and control groups, respectively. However, in White [26], both groups (yoga and control) reported significantly greater self-esteem and self-regulation over time. Lastly, Hagins et al. [32] found that yoga did not reduce stress reactivity compared to a physical education class when students were submitted to stressor tasks. Effect size was found for mood indicators, anxiety and tension (POMS), self-esteem, and memory. The RCT of each article is described in detail in the text.	7
Discussion
Summary of evidence	19	Although most of the studies were classified as 2b, according to AHRQ evidence level criteria, which means low quality randomized control trials, this review shows beneficial effects of yoga-based interventions at school on both psychological and cognitive functions (effect size was found for mood indicators, anxiety and tension, self-esteem and memory), but the negative effects of yoga were also observed in some of the studies and might be explained to some extent by the adaptation process by children, the absence of attentional control, and the inadequacy of yoga practice for children. Future research requires greater standardization and must deal with the problem of appropriateness: what type of yoga-based intervention is most suitable for children and at what frequency and duration and observed variables.	16
Limitations	20	Not only is the number of RCTs low, but also the trials were of reduced methodology quality and had risk of bias in terms of design, reporting, and methodology. It is comprehensible that it is difficult to perform double-blinding studies with yoga, but blinding to the outcome assessors and data analyzer could be feasible and has not been reported. One limitation of this review is that it was not possible to calculate the effect size of all variables observed in the selected studies due to their heterogeneity.	16
Conclusions	21	This review analyzed nine peer-reviewed RCT studies, in which yoga was taught to children in a school setting. Outcome measures included psychological well-being and cognitive functions, such as attention and memory. Effect size was found for mood indicators, anxiety and tension (POMS), self-esteem, and memory. While supportive in many studies, the utility of yoga in educational settings is inconclusive due to the small number of randomized control trials in the literature. Even though only RCTs were reviewed, methodological and statistical problems might have contributed to the uncertainty: inadequate sample sizes, absence of control groups, variability in the type of yoga being taught, long duration of yoga sessions, inappropriate psychometric tools for children, and failure to measure intervening variables such as mindfulness and body awareness, which are important parts of yoga practice. This review suggests valuable effects of yoga-based interventions at school on both psychological status and cognitive function in some studies but future research requires greater standardization and must deal with the problem of appropriateness; what type of yoga-based intervention is most suitable for children, specifically in terms of the frequency and duration?	22
Funding
Funding	22	This research was funded by the FAPITEC Agency under Process no. 7838.UNI321.21944.25062013.	22

Adapted from [24].