Sympathetic nerve activity is decreased during device-guided slow breathing

Area of Science:

• Cardiovascular physiology
• Autonomic nervous system regulation
• Respiratory control

Background:

• Slow breathing (<10 breaths/min) is known to reduce blood pressure (BP), but the underlying mechanisms require further elucidation.
• The role of the muscle sympathetic nerve activity (MSNA) in mediating BP reduction during slow breathing is not fully understood.
• Investigating the impact of guided slow breathing versus passive listening to music on autonomic function offers insights into BP regulation.

Purpose of the Study:

• To assess the acute effects of device-guided slow breathing (BIM) and calm music on MSNA, BP, and heart rate (HR) in treated mild hypertensives.
• To differentiate the physiological responses between active, device-guided slow breathing and passive music listening.
• To clarify the mechanisms by which slow breathing influences cardiovascular parameters and sympathetic outflow.

Main Methods:

• A randomized controlled study involving 27 treated mild hypertensives.
• Inclusion of a device-guided slow breathing (BIM) group (n=14) and a calm music group (n=13).
• Measurement of MSNA, BP, and HR before, during, and after a 15-minute intervention period.

Main Results:

• Device-guided slow breathing (BIM) reduced respiratory rate from 16±3 to 5.5±1.8 breaths/min (P<0.05).
• Both BIM and calm music reduced systolic BP (by -6 and -4 mm Hg, respectively) and diastolic BP (by -4 and -3 mm Hg, respectively).
• Only BIM significantly reduced MSNA (by -8 bursts/min) and did not alter HR.

Conclusions:

• Both device-guided slow breathing and calm music effectively lower BP in mild hypertensives.
• Device-guided slow breathing uniquely reduces peripheral sympathetic nerve activity, suggesting a key mechanism for its BP-lowering effect.
• This study highlights the differential impact of active versus passive auditory stimuli on autonomic control and cardiovascular health.