Figures
- Figure 1
Maximum HRV is typically observed at about a respiratory frequency of 6 breaths per min (0.1 Hz). Reproduced from [25] with permission from the publisher.
- Figure 2
Simplified model of cardiorespiratory control showing coupling between respiratory and cardiovascular systems. τ: circulatory delay; ILV: instantaneous lung volume; HR: heart rate; CNS: central nervous system; SAP: systolic arterial pressure; DAP: diastolic arterial pressure. Reproduced from [108] with permission from the publisher.
Tables
- Table 1
Documented effects of slow breathing in the healthy human body as referenced throughout this review
Respiratory Generally coincides with increased tidal volume and may enhance diaphragmatic excursion [16, 18]
Enhances ventilation efficiency and arterial oxygenation via alveolar recruitment, and distension and reduction of alveolar dead space [23, 24]
Moderates chemoreflex sensitivity [21]Cardiovascular Increases venous return → increases filling of the right heart → increases stroke volume → increases cardiac output [29, 30, 32, 35]
Causes blood pressure pulse fluctuations to synchronise with heart beat rhythm [29]
Synchronisation of vasomotion [34]
May entrain and enhance vasomotion (and microflow), i.e. to improve blood oxygenation [34]
Increases HRV and blood pressure fluctuations [21, 41, 42, 62]
May decrease mean blood pressure [30, 41, 43, 44]Cardiorespiratory Augments LF HRV and baroreflex sensitivity [41, 60, 65, 66, 77]
Increases RSA (maximises around 6 breaths per min (resonant frequency)) [41, 61, 62, 72–75]
Improves pulmonary gas exchange efficiency [45, 47, 48, 78–80], minimises cardiac work [74, 80, 81], buffers blood pressure fluctuations [29, 35]
Clustering of heartbeats within inspiratory phase (cardiorespiratory coupling) [46, 47]
Synchronisation of pulse harmonics of blood flow and heart rhythm [29]Autonomic nervous system Increases vagal activity (vagal tone) [42, 103]
Shift towards parasympathetic dominance [42, 105]
Augments vagal power (entrainment of cardiac resetting by vagus to respiration phases) [97, 103]
Optimises acetylcholine release and hydrolysis at SA node [67, 76]
Enhances phasic modulation of sympathetic activity [104, 106]
Improves autonomic responsiveness to physical perturbations (i.e. standing) [107]
Optimises sympathovagal balance [107]Hypotheses and plausible speculations are italicised.
Vol 13 Issue 4
Table of Contents
The physiological effects of slow breathing in the healthy human
