How does yoga breathing work to improve our heart rate variability?
Research Study At A Glance
Research Study At A Glance
The Research Question Asked
Is the positive impact of yogic breathing on heart rate variability a result of vagal nerve activity?
Type of Study
Clinical study – randomized control trial
Study Participants (Sample)
Sample size: six
Study participants:
- Two women, four men
- Age: between 18-25
- No previous yoga breathing experience
- Healthy: no physical health issues
Methods
Participants received one of three treatments: a chemical that blocked the activity of the parasympathetic nervous system (glycopyrrolate), a chemical that blocked the activity of the sympathetic nervous system (esmolol), or an inactive saline solution as a control treatment. All study participants completed 11 repetitions of a paced yoga breathing exercise and had their heart rate variability measured.
Results
There was a significant decrease in heart rate variability in participants when the action of the parasympathetic nervous system was blocked by the chemical treatment. This indicates that activity by the parasympathetic nervous system, specifically the vagal nerve, is involved when we see the positive effect of increased heart rate variability in response to the type of low breathing rates that occur in yoga practice.
Conclusion
Activity of the parasympathetic nervous system, and specifically the vagal nerve, is at least some part of the physiological process that in turn increases heart rate variability. Heart rate variability creates many of the positive effects that we experience when we do yogic breathing practices.
Background
Research shows that breathing techniques used in yoga have positive associations with many measures of physical and psychological health. For example, yoga breathing reduced inflammation, reduced measures of high blood pressure, reduced reports of both anxiety and depression, as well as improved heart rate variability (HRV). Good heart rate variability is one indicator of healthy cardiovascular and nervous system function. Heart rate variability is the gap between heartbeats and the amount of variability in the time between those heartbeats. This is measured in small time frames, less than a second, so we can see that variability.
The next step for researchers is to determine why yogic breathing practices have these benefits. What is the mechanism that is happening in the body/mind? This study looks specifically at one hypothesis for why yogic breathing might improve HRV. One hypothesis involves the influence of these yoga breathing practices on the vagal nerve. The vagal nerve is an important part of the parasympathetic nervous system. It’s key for keeping the nervous system in balance between activity and rest.
Research question
Is the positive impact of yogic breathing on heart rate variability a result of vagal nerve activity?
Research methods
One way that researchers can determine whether yogic breathing involves one or both parts of the autonomic nervous system (a part of the nervous system that manages involuntary physiological activity in the body) to influence HRV, is to block one aspect of the nervous system at a time with a chemical and then measure participants’ HRV during yogic breathing practices. In this study, participants received one of three treatments: a chemical that blocked the activity of the parasympathetic nervous system (glycopyrrolate), a chemical that blocked the activity of the sympathetic nervous system (esmolol), or an inactive saline solution as a control treatment. Participants did not know which of the treatments they received.
All study participants completed 11 repetitions of a paced yoga breathing exercise at different rates. The breathing exercises were at a pace of 4-9 breaths per minute for 60 seconds each time. The breathing cycle that participants were guided through included a 4-count inhale, then a 4-count retention, then a 6-count exhale, followed by a 2-count retention. All study participants had their HRV measured.
Results
Heart rate variability was significantly reduced at all breathing rates when the chemical (glycopyrrolate) which blocks the activity of the parasympathetic nervous system was given to study participants. This result suggests that activity by the parasympathetic nervous system, specifically the vagal nerve, is involved when we see the beneficial HRV increase that occurs at low breathing rates like the type of breathing rates that would occur in yogic breathing practices. There was no difference in HRV at any breathing rate between study participants who were given the control treatment (an inactive saline solution) and participants who received the chemical (esmolol) which blocks action by the sympathetic nervous system.
Why is this relevant to yoga practitioners?
Breathing is a key part of yoga practice that has demonstrated positive effects on health. Additionally, healthy heart rate variability is an indication of the health of many aspects of both the cardiovascular and nervous systems. This study indicates that one of the things that yoga breathing does is improve HRV by way of activating the vagal nerve in the parasympathetic nervous system. It’s important then, as yoga practitioners, to put some emphasis on our breathing when we practice.
Conclusion
This study reaffirms that it is worth prioritizing and emphasizing the breathing when you do a yoga practice. While the asanas themselves may have their own health and wellness benefits, don’t neglect the breathing during your practice. This research suggests that we can experience benefits as a result of slow yogic breathing.
