Breathe Deep to Explore the Heart’s Physiology

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Breathe in, breathe out. You may have heard that deep breathing techniques are good for your health because they can help you relax and manage stress. You may not know that they are also useful teaching tools for learning about cardiovascular physiology—the study of how the heart and blood vessels work.

Breathing—particularly deep breathing—can cause heart rate variability, also known as normal sinus arrhythmia or respiratory sinus arrhythmia. Heart rate variability is a measure of the normal differences in the amount of time between one heartbeat and the next. When you breathe in, your heart rate speeds up because more blood flows to your heart. This activates a part of your nervous system that lowers heart rate and blood flow. So when you breathe out, your heart rate slows down. 

A recent study in Advances in Physiology Education, describes an experiment in which two types of breathing techniques typically associated with yoga and meditation helped physiology students learn about the relationship between breathing and heart rate variability. In the exercise, the students’ heart rate and breathing patterns were monitored as they used either deep breathing or alternate nostril breathing—a deep-breathing technique in which you inhale and exhale through one nostril at a time. Both of these calming breathing methods are used in yoga and meditation.

The students looked at the differences in heart rate variability for each breathing method and compared them to a group of people that breathed normally throughout the experiment. The students used their knowledge of the autonomic nervous system—which controls functions we don’t think about such as heartbeat, breathing and digestion—in their discussions about the study. The class determined that deep breathing had a significant effect on heart rate variability—more so than alternate nostril breathing.

So, next time you’re doing yoga or destressing with a series of deep breaths, know that it’s not just your lungs and mind that are experiencing the change. Your heart and nervous system are also contributing to your feeling of calm.


Audrey Vasausakas, PhD

Audrey A. Vasauskas, PhD, is an associate professor of physiology at the Alabama College of Osteopathic Medicine. She is a former volunteer editor for the I Spy Physiology blog.

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