Investigating components of pranayama for effects on heart rate variability

A randomized crossover trial in healthy adults s by Ryan Bradley and team at the Institute National University of Natural Medicine, Portland, OR shows that slow, externally paced breathing whether simple deep breathing or Sheetali/Sheetkari pranayama produces the largest increases in RMSSD, a key heart-rate variability marker of parasympathetic activity. Mouth shaped “cooling” breaths may add small extra benefits, but slow pacing itself appears to be the dominant driver of autonomic change.