Figure 9
From: On the cardiorespiratory coordination assessed by the photoplethysmography imaging technique

Correlation of cardiac RMSSD and cardiorespiratory coordination (CRC). Negative correlation between mean cardiac RMSSD values and CRC throughout the whole measurement and across all groups. Elevated cardiac RMSSD levels correspond with low CRC levels, and vice versa. Higher CRC during states of sympathetic dominance are in line with increased CRC in pathological states.