Regions of cardiorespiratory synchronization in humans under paced respiration

Cardiorespiratory synchronization under paced respiration is studied systematically as the respiration frequency is changed between 3 and 30 breaths per min. We plot a one-dimensional cut of the classical picture of synchronization regions along the line defining the current breathing amplitude. The existence of $n:m$ synchronization regions of finite width is demonstrated for each of six subjects studied. The statistics of the different types of synchronization and their stability are discussed.