Key Points
Controlled breathing reduces sympathetic activity, even when performed at a relatively fast pace
The reduction in sympathetic activity might be due to increased focus or increased tidal volume
The Breathing Diabetic Summary
Several studies have shown the positive effects of slow, controlled breathing. For example, Oneda et al. (2010) showed that slow breathing reduced blood pressure, heart rate, and sympathetic activity in hypertensive patients. A study published in Nature showed that slow breathing increased autonomic function, arterial function, and blood oxygen saturation in type 1 diabetics.
However, in most studies looking at controlled breathing, the breathing rate is controlled and reduced. The current study examined the role of the “controlled” part. That is, are the benefits due to controlling respiration or slowing it down?
To do this, they had participants breathe both spontaneously and at a controlled pace of 12 breaths/min. A rate of 12 breaths/min was chosen because it is a “typical” breathing rate given in most physiological textbooks.
They found that the controlled breathing lowered sympathetic activity, but it did not lower blood pressure. Thus, this relatively “fast” pace compared to other studies (typically 6 breaths/min) still lowered sympathetic activity.
Interestingly, several patients actually had a slower spontaneous breathing rate (~5-9 breaths/min) than the controlled pace. But, even in these patients, their sympathetic activity was lowered when they switched to the controlled pace. This suggests that there is a “meditative/focus” aspect of controlling your breath that relaxes you and lowers sympathetic activity.
Overall, this study shows that simply controlling your breathing rate can lower sympathetic activity. Therefore, if you are not yet able to drop into the 4-6 breaths/min range (which is usually suggested), there are still benefits to using an app to control your breathing rate at a pace that is comfortable to you.
Abstract
Controlled or paced breathing is often used as a stress reduction technique but the impact on blood pressure (BP) and sympathetic outflow have not been consistently reported. The purpose of this study was to determine whether a controlled breathing (12 breaths/min, CB) rate would be similar to an individual’s spontaneous breathing (SB) rate. Secondly, would a CB rate of 12 breaths/min alter heart rate (HR), BP, and indices of muscle sympathetic nerve activity (MSNA). Twenty-one subjects (10 women, 11 men) performed two trials: SB, where the subject chose a comfortable breathing rate; and CB, where the subject breathed at a pace of 12 breaths/min. Each trial was 6 min during which respiratory waveforms, HR, BP (systolic, SBP; diastolic, DBP), and MSNA were recorded. During CB, the 6 min average breathing frequency (14±4 vs 12±1 breaths/min, P<0.05 for SB and CB, respectively), MSNA burst frequency (18±12 vs 14±10 bursts/min, P<0.01) and MSNA burst incidence (28±19 vs 21± 6 bursts/100 heart beats, P<0.01) were significantly lower than during SB. HR (66±9 vs 67±9 beats/min, P<0.05) was higher during CB. SBP (120±13 vs 121±15 mmHg, P=0.741), DBP (56±8 vs 57±9 mmHg, P=0.768), and MSNA total activity (166± 94 vs 145±102 a.u./min, P=0.145) were not different between the breathing conditions. In conclusion, an acute reduction in\ breathing frequency such as that observed during CB elicited a decrease in indices of MSNA (burst frequency and incidence) with no change in BP.
Journal Reference:
McClain SL, Brooks AM, Jarvis SS. An acute bout of a controlled breathing frequency lowers sympathetic neural outflow but not blood pressure in healthy normotensive subjects. Int J Exerc Sci. 2017;10(2):188-196.