We identified 26 controlled studies of yoga for the pediatric and 9 for the young adult population. The methodological quality of many studies was low. Areas for which yoga has been studied include physical fitness, cardio-respiratory effects, mental health, behavior and development, irritable bowel syndrome, eating disorders, and prenatal effects on birth outcomes. A large majority of the studies were positive, but due to methodological limitations the evidence provided is preliminary at best.
Our review differs from the recent systematic review of yoga for children published by Galantino et al. These authors used search terms related to yoga, pediatrics (children, developmental disabilities), exercise, and publication types that were of interest. Studies were included with primary outcomes of quality of life, cardio-respiratory fitness, and physical functioning or with secondary outcomes of attention and cognition. The review categorized studies based on relevance to physical therapy into three domains: neuromuscular, cardiopulmonary, and musculoskeletal headings. Whereas we identified 34 studies including NRCTs and RCTs, the Galantino review identified 24 studies including cohort, case-control, and RCTs. Among the 34 trials included in our review, 18 studies (11 RCTs and 7 NRCTs) are unique to our study and are not reported by Galantino.19, 20, 22, 24, 25, 29, 31, 34–36, 40–42, 47, 50–53
Our study reviewed 16 studies also in the Galantino review,21, 23, 26, 27, 30, 32, 33, 37–39, 43–46, 48, 49
with the remaining 8 studies excluded here based on our exclusion criteria as follows: age,54–57
no control group,58–60
and not a trial.61
The differences in our review may have stemmed from contrasting search strategies including: different search terms (e.g. infant, adolescent), our specific age inclusion criteria (0 to 21 years), and our inclusion of all outcomes (not only quality of life, attention, and cognition).
Preliminary evidence presented in this review suggests that yoga may be beneficial for physical fitness and cardio-respiratory health among children. As a physical form of exercise, studies suggest that yoga provides low aerobic intensity.62, 63
According to the 2002 NHIS, a large majority of adults who use yoga in the U.S. reported that yoga was important for their health maintenance.3
Based on our review, yoga may be an option for children to increase physical activity and fitness. In particular, yoga may be a gateway for adopting a healthy active lifestyle for sedentary children who are intimidated by more vigorous forms of exercise. However, studies have been predominately conducted in India, where yoga is culturally more acceptable and adaptable.64
Studies in different cultural settings are necessary to better evaluate the feasibility of yoga as a form of exercise for children.
More studies outside of India have explored the use of yoga for psychological health. This research focus is consistent with a national survey among adults in the U.S., where yoga users were more likely to have mental health conditions, and mental health was one of the most common conditions yoga was used to treat.3
A systematic review by Pilkington in 2005 found yoga may be beneficial for adults with depression. We identified two NRCTs that suggested yoga, as well as conventional exercise (swimming or dance), promoted mental health. However these studies were among young adults, and have to be replicated for individuals less than 18 years old.
As a means of developing mental and physical discipline and self-awareness, yoga intuitively would have possible benefit for children with ADHD. However, to date initial studies show potential, but are far from conclusive. In general, the clinical applications of yoga for pediatric behavior and development have yet to be determined.
Prenatal yoga has become increasingly popular in mainstream culture in the U.S., but surprisingly, we found only one study from India that measured health outcomes on neonates. While a positive NRCT, this study needs to be followed by more rigorous research to evaluate the application of yoga for this population.
Our review suggests need for improved methodology and reporting of yoga studies in children. Many RCTs did not describe randomization methods. None of the studies provided sample size calculations, and many had small sample sizes. These studies may not have sufficient power to measure changes in reported outcomes. In addition, inappropriate statistical analysis of within group pre/post changes rather than between group comparisons undermines the principle of conducting an RCT. Studies need to explain the rationale of the control groups, including why the control group is an appropriate comparison to the yoga intervention group. Most studies did not report withdrawals/dropouts, which is necessary to determine feasibility and adherence to the protocol, along with an intention-to-treat analysis. None of the 34 studies reported adverse events or lack thereof. This may suggest that yoga is a low risk intervention among children. However, since this was not specifically reported in these trials, it also may represent underreporting of adverse events. The risks of yoga have not been well documented with some case reports in the literature.65–73
Future prospective controlled studies should collect data on adverse events.
Yoga represents a myriad of practices, and we found that studies lacked adequate description of the yoga interventions. Without detailed description of the specific techniques used, comparison and replication of studies to validate results are difficult. Also, the qualifications of yoga instructor(s) need to be clearly stated due to variations in style and experience. Registration of yoga teachers with national standards of yoga training, such as the minimum of 200 training hours recognized by the Yoga Alliance (www.yogaalliance.org
), will help standardize yoga interventions. However, these standards apply to training yoga instructors to teach adults, while no standards exist for instructors teaching children. Specific training and experience teaching yoga to children should be described.
There are limitations to our study including the low number of publications, especially for any given outcome. This precludes further analysis with quantitative methods such as meta-analysis for specific outcomes. The variability of yoga interventions and the lack of detail in yoga description make comparison and interpretation of these studies difficult. Studies spanned a broad age range, and yoga for different age groups is difficult to compare based on varying developmental age and medical conditions. Yoga very likely has different effects and feasibility among different age groups. Based on experienced yoga teachers, younger children are often taught yoga that emphasizes physical exertion with many dynamic postures, and less breathing and meditation. As children grow older, more breathing and meditation are incorporated. This reflects the developmental stage of the child to allow them to be engaged and focused in the practice. This systematic review does not provide sufficient data to identify particular patterns of yoga for specific populations and settings. We excluded studies with mixed populations of children and adults. Generally, studies among all age groups were positive, however publication bias cannot be ruled out in this descriptive systematic review. We also excluded studies that were not controlled, and these studies may have contributed some valuable information. However, the absence of control groups in trials, particularly behavioral trials, make any result highly suspect with placebo effects and other sources of confounding. Studies published in languages other than English were excluded, which may have caused language bias. Our definition of yoga was narrow, and excluded practices that contain similar or co-opted relaxation techniques. For example, mindfulness-based stress reduction commonly incorporates some aspects of yoga in the intervention. For reasons of practicality, we limited our study to interventions that were clearly described as yoga or yoga-based. Despite these limitations, our systematic review describes the state of research for yoga in children, and can help direct future investigations.
As yoga continues to gain in popularity among children as a recreational activity or a behavioral therapy, there are a wide variety of traditions and styles. These variations are not clearly delineated by age. Although there is a growing body of literature, the existing methodology is very poor. Thus, it is difficult to comment on the clinical efficacy. The trials did not report adverse events, suggesting that yoga has a high safety profile. Further research is necessary to identify clinical applications of yoga for children. As a mind-body modality, applications in pediatric mental health and physical fitness need to be studied. Research on the use of yoga for disorders of behavior and development, such as ADHD, need to be developed. Research needs to be conducted with rigorous methodology in RCTs with detailed description of protocols and reporting of results. RCTs of yoga should utilize guidelines established by the Consolidated Standards of Reporting Trials (CONSORT) group for the reporting of trials.74
In addition, methodological issues specific to mind-body interventions should be addressed including adequate description of the intervention and control group, and single blinding of the outcome assessor. Evidence-based prescription of mind-body techniques, such as yoga, for overall health maintenance or for specific diseases in children will depend on the development of this research agenda.