The connection between the heart and breath has long been recognized by ancient and contemporary cultures and spiritual leaders.
Nicephorus the Solitary said that "breathing is a natural way to the heart." Spiritual leader and peace activist Thich Nhat Hanh elegantly captured the heart-breath connection: "Happiness lies in your heart. You only need to practice mindful breathing for a few seconds, and you'll be happy right away."
Beyond this subtle relationship, the heart and breath are also physically connected. The left lung is actually smaller than the right to make room for the heart. Research shows us that the connection goes even deeper, and the heart and breath are more synchronized than you might have thought.
Let's look at how.
Respiratory Sinus Arrhythmia: The Breath's Gateway to the Heart
Each breath we take impacts our heart rate. During inhalation, the lungs and heart expand, lowering blood pressure in the heart, and the brain responds by sending a signal for the heart rate to increase.
The reverse happens every time you exhale. The heart contracts, blood pressure increases, and the brain sends a signal to the heart to slow down. An excellent video of this can be found here.
These signals are mediated through the autonomic nervous system. The sympathetic (fight-or-flight) branch becomes more dominant during inhalation, which increases the heart rate. During exhalation, the parasympathetic (rest-and-digest) branch is activated, slowing the heart rate down (this is also why taking a nice slow, extended exhalation is so calming).
This delicate breath-heart connection is known as "respiratory sinus arrhythmia," or RSA. RSA is one reason our heart does not beat like a metronome but has variability throughout each breath cycle. And as you probably know, this heart rate variability (HRV) is a significant marker of our overall health.
Harmony, HRV, and How Slow Breathing Can Improve Our Health
Heart rate variability is the beat-to-beat variation in our heart rate. Broadly, it represents our resiliency, our body's ability to adapt quickly and rebound from changing conditions.
Decades of research have uncovered the importance of HRV for overall health and wellness. It has been discovered that low HRV is correlated with adverse outcomes such as a shorter life, increased risk of heart attack, and impaired cognitive function, among others.
Encouragingly, our breath can be used to increase HRV. Specifically, breathing at a rate of 5-6 breaths/minute (sometimes called "resonant breathing" or simply slow breathing) is the sweet spot for boosting cardiovascular function. Click here for a simple resonant breathing practice video to save for later.
When we breathe at this rate, signals from our respiratory, cardiovascular, and autonomic nervous systems all harmonize. This increases the heart rate fluctuations with each breath, increasing HRV. With time and consistent practice, this harmony makes our bodies run more efficiently, lowering blood pressure, increasing blood flow, reducing inflammation, reducing stress and anxiety, and helping us live healthier lives.
Pretty remarkable results for just breathing slowly.
But there's another significant way our breath and heart interact, and it involves the size of our lungs.
Lung Capacity: 20 Years of Heart Research Shows Us How to Live Longer
The Framingham Heart Study began in 1948 and has included over 14,000 people spanning three generations. Its main goal was to understand cardiovascular disease risk factors better. There have now been over 3,000 publications related to this larger objective.
But in the early 80s, a paper using 20 years of its data was published with a pretty unexpected finding:
"They gathered two decades of data from 5,200 subjects, crunched the numbers, and discovered that the greatest indicator of life span...was lung capacity…larger lungs equaled longer lives." – James Nestor, Breath.
So not only can we boost heart health by breathing slowly, but we can also reduce our risk of cardiovascular disease and death by increasing our lung capacity. The breath-heart connection is indeed powerful.
A Recap of the Heart-Breath Connection
Our breath is intricately linked to our hearts. On a second-by-second basis, each breath we take influences our heart rate. Over several minutes, our breathing rate can harmonize our respiratory, cardiovascular, and autonomic nervous systems, allowing our bodies to function optimally. Lastly, greater lung capacity is associated with less risk of cardiovascular disease.
In an upcoming post, we'll examine different breathing techniques we can use to benefit from this heart-breath connection to boost our health.
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These are expert opinions on lifestyle from professionals who are board-certified physicians, registered dietitians, or healthcare professionals. This content does not represent any medical advice for the prevention or treatment of any medical diseases.