Cardiac coherence

Cardiac coherence is a smooth, wave-like heart rhythm in which heart rate, blood pressure and breathing oscillate in step, usually near 0.1 Hz. It is most easily reached by slow, even breathing at about five to six breaths per minute and is associated with calm, focused alertness rather than sleepiness.

In this state the heart speeds up gently on each inhale and slows on each exhale, and the baroreflex amplifies the swing, which shows up as high short-term heart-rate variability. Studies find breathing near this pace with equal inhale and exhale raises variability during practice; claims about lasting emotional or 'heart intelligence' effects are less well established. The Coherent pattern in the free Breathing Pacer uses this rhythm.