What is it about yoga? Isolating the effect of structured movement sequences on cognition, interoception, and stress markers

Yoga-based practices (YBP) typically involve a combination of movement sequences, conscious regulation of the breath, and techniques to engage attention. However, little is known about whether effects of YBP result from the synergistic combination of these components, or whether a subset may yield similar effects. In this study we compared the effect of two 8-week yoga programs: a movement-focused practice (involving movement, breath and controlled gaze), and a breath-focused practice (involving breath and controlled gaze). Healthy yoga naïve participants (age 18-35) were randomly assigned to one of the two programs, consisting of two weekly instructor-led classes and daily home practice assisted by videos. Perceived stress, salivary cortisol and sustained attention were assessed both before and after the program. While both groups showed a reduction in perceived stress and salivary cortisol after the program, only the breath-focused group showed improvements in sustained attention. Improvement in sustained attention was correlated with reduction in perceived stress but not with reduction in salivary cortisol. These findings will be discussed in the context of a theoretical framework outlining bottom-up neurophysiological and top-down neurocognitive mechanisms hypothesized to be engaged by YBP.