A Guide to HRV: The Impact of Breathing

In this video we're going to talk about breath, and how breathing can affect your heart rate, your heart rate variability and the autonomic nervous system. In particular, we can talk about breathing techniques that can help regulate or calm your autonomic nervous system to your benefit.

We think about the autonomic nervous system as that part of our primitive brain that automatically puts in place all the things we are doing but don't have to think about doing, such as breathing, our heart rate, temperature regulation, peristalsis — which is contraction of your gut — and sweating. Now, it turns out that breathing, when you don't think about it, is under the thrall of the autonomic nervous system. But the power of the breath is that it is the one component affected by your autonomic nervous system that has a dual control. That means it responds to subconscious commands when you're not aware. But importantly, you can take control of your breath, because now I can do a conscious breath. [Demonstrates.] And I've completely changed the cadence of my breath. We can talk specifically about how delivering specific inputs can trigger a change or a modulation in the autonomic balance in the autonomic nervous system through breathwork.

In controlling your breath, the first step is being aware of your breath. For example, a very upper-chest, high rate of breathing, mainly mouth breathing, not nasal breathing — these are all markers of breathing through the lens of a highly expressed sympathetic nervous system, or fight-or-flight response. And that's the exact opposite of what we would like for most of our patients.

Once they become aware of their breathing, we go to step two, which is to take control of their breath consciously. There are several principles of breathing that I always say to my patients are pretty critical beyond awareness.

The first is to take an active breath through your nose, which means actively close your mouth and breathe in nasally. That's number one.

Number two: try to breathe into your diaphragm, which means a belly breath. The easiest way to demonstrate this is to put one hand on your chest and one hand on your belly. On the breath in, the belly should expand outwards, like this. [Demonstrates.] And on the breath out, the belly button should touch the spine. [Demonstrates.] The chest need not move if we're doing that breath pattern. So we're nasal, and we're diaphragmatic or belly breathing.

The third component is the cadence: slow and rhythmic. So slow down the breath and make it rhythmic, which means that the rate of flow of air through your nose needs to be constant throughout the breathing cycle. The ideal breath is said to be a breath that takes five and a half seconds in and five and a half seconds out. Now, for most patients, that's going to be a long time. But whatever cadence you choose — let's say four seconds in, four seconds out — breathe in through the nose and make the rate of flow of air the same throughout those four seconds, which means it's a breath that is steady. [Demonstrates.]

That steadiness of the breath will do something very powerful to your autonomic nervous system. It will change the inputs and regulate the inputs almost in a sinusoidal pattern, where you go up and down in a nice, gentle curve. That form of breathing is called coherent breathwork.

So just to recap: nasal breathing, into the diaphragm; the cadence needs to be slow, ideally five and a half seconds, and rhythmic, which means the rate of breath needs to be the same throughout.

Now, the fifth thing, which is a bonus point, is to breathe into the heart. This means that when you breathe, after you've settled into a motion of breathing — for example, for two minutes or five minutes — and it becomes second nature, bring in a positive feeling. That's because the combination of accessing and modifying the autonomic nervous system through what's called a bottom-up approach — i.e. taking a breath to influence the inputs into your autonomic nervous system — combined with a top-down approach, which is changing your thoughts and emotional state to bring in something positive, to feel gratitude or compassion, is the most powerful way, in my experience, to settle and regulate your autonomic nervous system. This is one of the reasons why meditation, which encompasses both breathwork and mindfulness, is a particularly potent combination to regulate the autonomic nervous system and heart rate variability.

The specific way in which breathing controls the autonomic nervous system directly is through a phenomenon called respiratory sinus arrhythmia. Respiratory sinus arrhythmia is actually the fundamental basis for heart rate variability, and it goes something like this: you take a deep breath in and your heart rate goes up, and you take a deep breath out and your heart rate goes down. This variability in the heart rate going up and down, and up and down, in cycle and in concert with your breath — inhale and exhale — is what gives you, at a fundamental level, heart rate variability.

There are many types of breathing exercises, and it can be confusing to understand which would be the best breathing exercise for you. When we think about the autonomic nervous system, in my opinion, the most important breathing exercise to practise on a regular basis is coherent breathing. Not everyone will achieve five and a half seconds in and out on the first go. You might start with two seconds in, two seconds out. But keep up with the practice. Do it daily, two minutes a day. Tomorrow, do two and a half seconds in, two and a half seconds out. You will feel more comfortable slowing your breath down, and you'll know you are recalibrating your body's homeostasis.

Regular practice of coherent breathing has been shown to reduce inflammation, to help patients feel more calm and to sleep better. And HRV, or heart rate variability — a marker of the autonomic nervous system — can be improved by regular coherent breathing practice.

How much time should you spend practising coherent breathing? I would say a minimum of 10 minutes, at least twice a day — ideally when you first wake up and before you go to bed. The benefits of coherent breathing extend way beyond the time of practice. In fact, if you practise more on a daily or weekly basis, you will notice that your HRV improves over that time.

What I'd like to introduce is the idea that the autonomic nervous system has truly multifaceted input. What drives you into a fight-or-flight response may not only be a dysfunctional breathing pattern. It could be the fact that your blood pressure is low, it could be the fact that you are not hydrating enough, it could be the fact that you're still living with your mother-in-law. All these factors clearly are inputs into the autonomic nervous system, and what we're talking about is addressing some of the ways in which we can influence them that are under our control. You might not be able to control how your mother-in-law speaks to you, but you can certainly control your breath. But you also have to think: am I hydrating well? Am I sleeping well? Am I going for a walk, or doing as much as I can without triggering post-exertional fatigue? Am I doing all the other things around the edges of the inputs into the autonomic nervous system? But breath is a fundamental that everyone with a complex chronic illness needs to do.

To recap, controlling your breathing can influence autonomic nervous system function. Specifically, if you breathe in a particular way — and I would recommend coherent breathing — over a period of time you can regulate your autonomic nervous system so it moves away from being so dominantly in fight-or-flight mode, shifting back towards a more balanced, rest-and-digest dominant mode. Over time, breathing in a coherent way can help improve heart rate variability and improve your symptoms.