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. 2014 Oct;22(5):920-9.
doi: 10.1016/j.ctim.2014.08.008. Epub 2014 Sep 4.

Comparison groups in yoga research: a systematic review and critical evaluation of the literature

Crystal L Park  1 , Erik Groessl  2 , Meghan Maiya  3 , Andrew Sarkin  3 , Susan V Eisen  4 , Kristen Riley  5 , A Rani Elwy  4
Affiliations

Comparison groups in yoga research: a systematic review and critical evaluation of the literature

Crystal L Park et al. Complement Ther Med. 2014 Oct.

Abstract

Objectives: Comparison groups are essential for accurate testing and interpretation of yoga intervention trials. However, selecting proper comparison groups is difficult because yoga comprises a very heterogeneous set of practices and its mechanisms of effect have not been conclusively established.

Methods: We conducted a systematic review of the control and comparison groups used in published randomized controlled trials (RCTs) of yoga.

Results: We located 128 RCTs that met our inclusion criteria; of these, 65 included only a passive control and 63 included at least one active comparison group. Primary comparison groups were physical exercise (43%), relaxation/meditation (20%), and education (16%). Studies rarely provided a strong rationale for choice of comparison. Considering year of publication, the use of active controls in yoga research appears to be slowly increasing over time.

Conclusions: Given that yoga has been established as a potentially powerful intervention, future research should use active control groups. Further, care is needed to select comparison conditions that help to isolate the specific mechanisms of yoga's effects.

Keywords: Comparison group; Control group; Randomized controlled trials; Systematic review; Yoga.

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Conflict of interest statement

Conflict of Interest Statement: None declared.

Figures

Figure 1
Figure 1
Number of yoga intervention studies using passive and active comparison conditions
Figure 2
Figure 2
Number of Studies with Passive Only Control Conditions versus Studies with Active Comparison Conditions by Year (ending mid-2012)
See this image and copyright information in PMC

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