The present study found that, in nearly all forms of slow
breathing performed in yogic breathing naive participants,
there were increased BRS (only slow breathing with ujjayi
during inspiration and expiration did not result statistically
significant) and oxygen saturation, with reduced blood pressures
and chemoreflex sensitivity. The greatest improvement
was found in slow breathing without ujjayi, while breathing
controlled at a rate of 15/min caused a drop in BRS. In all
forms of slow breathing there was a statistically significant
increase in oxygen saturation from the mean baseline of
98.3%, confirming the relationship between high levels of
oxygen absorption and BRS. However, ujjayi breath showed
the greatest saturation (albeit only 0.1–.0.2% percent greater),
but it did not correspond to the greatest improvement in BRS,
likely due to the increased respiratory effort (as seen by the
increased heart rate). The increase in BRS was mirrored by a
reciprocal drop in chemoreflex estimate. No significant difference
was found between asymmetrical versus symmetrical
breathing at 6 breaths per minute. These results show that
simple slow breathing with equal inspiration/expiration is the
best compromise to obtain positive cardiorespiratory effects
in yoga naive subjects.