Spontaneous respiratory modulation improves cardiovascular control in essential hypertension - Pinheiro et al. (2007)
Slow breathing reduces blood pressure and improves heart rate variability in hypertensive patients
Practicing slow breathing reduces resting respiratory rate
Slow breathing decreases sympathetic nervous system activity
The Breathing Diabetic Summary
They had a really small sample size of 10 hypertensive patients, but I guess we have to take what we can get with breathing studies.
The breathing protocol was different from most of the other studies I have reviewed here. Instead of using a device to guide the patients toward slow breathing, they had them become conscious of their breathing motions. For example, they were instructed to lie down and put their hands over different areas, for example, the chest, and identify the motions associated with each breath. Therefore, their technique was kind of a mindfulness meditation in addition to a breathing exercise. After becoming aware of their breathing motions, the subjects were instructed to gradually decrease their breathing rate while increasing the amplitude of each breath. They performed this routine lying down, and then they sat up and did it again. The protocol lasted 30 minutes and was practiced twice a week for one month.
The key outcomes they measured were blood pressure, heart rate variability, and different respiratory variables, such as tidal volume and breathing rate.
Importantly (I know I’m sounding like a broken record here), the patients did not change their medication or lifestyle: they simply added 30 minutes of slow breathing twice a week.
Systolic, diastolic, and overall mean blood pressure were all significantly reduced at the end of the study. Heart rate variability was also improved. And, similar to Howorka et al. (2013), they found a reduction in the patients’ natural breathing rates, dropping from ~15 breaths/min at the beginning of the study to ~10 breaths/min at the end of the study.
The authors suspect that these positive results were due to improved autonomic function. Specifically, their results indicate that sympathetic activity was decreased (rather than parasympathetic activity being increased), which improved autonomic function in their subjects. Additionally, hypertensive patients show signs of hyperventilation at rest, which is likely caused by over activation of the sympathetic nervous system. Slow breathing lessens this effect by reducing sympathetic activity.
Overall, this paper shows that the practice of slow breathing can reduce blood pressure, improve heart rate variability, and decrease resting respiratory rate. They found that the improvements in the cardiovascular variables measured here were likely due to improved autonomic function via a reduction in sympathetic activity. A quote near the end of the paper summarizes it nicely:
“Slow breathing is a straightforward method with no contraindications that offers a rather valid cost-benefit, improving autonomic balance and respiratory control and lowering blood pressure in patients with essential hypertension.”
Sounds good to me!
Abstract from Paper
Background: Recent studies show that controlled breathing improves baroreflex and heart rate variability and lowers blood pressure in hypertensive patients.
Objective: To evaluate the effects of slow breathing training on cardiorespiratory system modulation of patients (n=10, men and women, ages ranging from 45 to 60) with essential hypertension seen in an outpatient setting.
Methods: According to the study design, each patient was used as his/her own control, and data were collected before and after the intervention. The following parameters were assessed: heart rate variability (HRV), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP), respirometry, chest expansion measurement, and statistical data analysis. Respiratory training was performed in 30 minute sessions held twice a week over one month using slow breathing exercises.
Results: Our results were as follows: a reduction in SBP, DPB, and MAP (p < 0.05 vs control); an increase in heart rate variability, as evidenced by greater RR interval variation and SDNN index; a decline in respiratory rate (p < 0.01 vs control); and an increase in tidal volume (p < 0.01 vs control) and thoracic expansibility (p < 0.01 vs control).
Conclusion: Respiratory retraining using the slow breathing technique appears to be a useful adjunctive for cardiorespiratory control in hypertensive patients.
Carlos Hermano da Justa Pinheiro, Renato Antônio Ribeiro Medeiros, Denise Gonçalves Moura Pinheiro, and Maria de Jesus Ferreira Marinho, (2007) Spontaneous respiratory modulation improves cardiovascular control in essential hypertension, Arq. Bras. Cardiol., 88 (6), 576 – 583.