Vagus Nerve Breathing: How Slow Breathing Calms Your Nervous System

By Simon Kerle, Founder of Raw Power Yoga and Vincere Protocol

Think about how you breathe under pressure: stuck in traffic, before a hard conversation, or holding a difficult yoga pose. Your breathing often gets faster, moves higher into your chest and may shift towards mouth breathing.

Now think about how you breathe at the end of class, lying in savasana. It is usually quieter, slower and more relaxed.

The relationship works both ways. Your physical and emotional state can change your breathing, and deliberately changing your breathing can influence your physiological state.

One of the systems involved is the vagus nerve.

Slow breathing can increase heart rate variability during the practice and influence parasympathetic activity, particularly when breathing is comfortable and controlled.

At Raw Power Yoga, we integrate breathing education through Vincere Protocol, the performance-breathing system I developed from my experience as an 18-year professional athlete, yoga teacher and Advanced Breathing Coach.

In this article, we will look at:

what the vagus nerve actually does
how slow breathing affects heart rate variability
why breathing lightly matters as much as breathing slowly
what the research does and does not show
a simple vagus nerve breathing exercise you can practise yourself

Your Two Gears: Go and Recover

Your autonomic nervous system controls many functions you do not consciously have to manage, including heart rate, blood pressure, digestion and aspects of breathing.

Two major branches are:

The sympathetic nervous system: your mobilisation or “go” system. It helps prepare the body for action.
The parasympathetic nervous system: associated with rest, digestion, recovery and energy conservation.

A healthy nervous system does not stay permanently in one state. It needs to adjust according to what the situation requires.

A yoga class is a good example: effort followed by recovery, activation followed by release.

Stress itself is not the enemy. The problem is prolonged or repeated stress without enough opportunity to recover.

What Is the Vagus Nerve?

The vagus nerve is the tenth cranial nerve and one of the major communication pathways between the brain and the body.

It travels from the brainstem through the neck and chest and has branches that communicate with structures including the heart, lungs and digestive system.

It is a two-way communication system.

A large proportion of vagal fibres carry information from the body towards the brain. Other fibres carry signals from the brain towards internal organs.

At the heart, vagal activity helps slow the natural pacemaker through the neurotransmitter acetylcholine.

This is one reason the vagus nerve is sometimes described as part of the body’s physiological braking system.

You cannot simply switch the vagus nerve on like you would contract a muscle, but breathing patterns can influence cardiovascular activity associated with vagal function.

What Is Vagal Tone?

“Vagal tone” refers broadly to the influence of the vagus nerve on physiological regulation, particularly the heart.

Researchers often estimate cardiac vagal activity using measures of heart rate variability, or HRV.

HRV describes the variation in time between individual heartbeats.

Greater variability is not automatically better in every situation, but HRV can provide useful information about autonomic regulation when it is measured consistently and interpreted in context.

How HRV Changes With Breathing

Your heart does not beat like a perfectly regular metronome.

During normal breathing, heart rate tends to rise slightly during inhalation and fall during exhalation.

This phenomenon is called respiratory sinus arrhythmia.

Slow breathing can make these fluctuations much larger.

This is why you may see HRV rise quickly when someone begins breathing slowly.

But there is an important distinction.

A higher HRV reading during slow breathing is not automatically evidence that someone’s resting HRV or long-term vagal regulation has improved.

If you track HRV, compare resting measurements taken under similar conditions across weeks rather than judging your progress from a single breathing session.

How Slow Breathing Influences the Vagus Nerve

Slow breathing has been used in yoga, meditation and other contemplative practices for centuries.

Modern physiology helps explain several mechanisms involved.

1. Breathing changes cardiac vagal activity

During inhalation, vagal influence on the heart tends to decrease. During exhalation, it tends to increase.

This contributes to the natural rise and fall in heart rate that occurs with breathing.

2. Slow breathing interacts with the baroreflex

The baroreflex is one of the systems your body uses to regulate blood pressure.

Breathing changes pressure within the chest and creates rhythmic cardiovascular changes.

At slower breathing rates, these rhythms can become more strongly synchronised with the baroreflex.

Research often finds particularly large HRV oscillations somewhere around approximately 4.5 to 7 breaths per minute, although the optimal rate varies between individuals.

3. The lungs send information back to the brain

Breathing changes stretch and mechanical signals coming from the lungs and chest.

These signals form part of the continuous feedback between the respiratory system, cardiovascular system and brain.

4. Breathing influences physiological arousal

Fast, irregular breathing commonly accompanies stress and physical effort.

Slower, quieter breathing is commonly associated with lower physiological arousal.

Changing the breathing pattern therefore gives you one practical way to influence your physiological state.

Slow Is Not the Only Goal. Light Matters Too.

This is one of the most important parts of breathing practice.

Slowing your respiratory rate does not automatically mean you are breathing less air.

If you breathe slowly but take very large breaths, total ventilation can remain high or even increase.

Breaths per minute × size of each breath = total ventilation per minute

That is why, in Vincere Protocol, we combine slower breathing with quiet, comfortable breathing.

The aim is not to suck in huge amounts of air.

The breath should remain gentle, controlled and predominantly nasal when appropriate.

If you become dizzy, tingly, distressed or feel that you are forcing the breath, return to normal breathing.

Where Does Carbon Dioxide Fit In?

Carbon dioxide is one of several important influences on breathing regulation.

Your breathing is shaped by multiple inputs including metabolism, blood chemistry, physical activity, signals from the lungs and muscles, emotions and wakefulness.

Breathing lightly can help avoid unnecessarily increasing ventilation while practising slow breathing.

The Vincere Protocol Breathing Pace

Research commonly places slow-breathing protocols within approximately 4.5 to 7 breaths per minute.

Rather than chasing the slowest possible breathing rate, we keep the progression simple.

Level 1: 3 Seconds In, 4 to 5 Seconds Out

This is where most people should begin.

Keep the breathing quiet and comfortable.

Do not increase the breath size simply to hit the timing.

Level 2: 4 Seconds In, 6 Seconds Out

This produces approximately six breaths per minute and sits within the range commonly used in slow-breathing and HRV research.

Do not force yourself to reach this pace.

If 4 seconds in and 6 seconds out requires large breaths, gasping or strain, return to Level 1.

A comfortable 3:4 breathing pattern is more useful than a forced 4:6 pattern.

Step by Step: Vagus Nerve Breathing Exercise

Try this practice for approximately 5 to 10 minutes.

Get comfortable. Sit upright or lie down in a relaxed position.
Breathe through your nose if comfortable. Keep the breathing quiet.
Allow the diaphragm and lower ribs to move. The abdomen and lower ribs should expand gently rather than forcing a large upper-chest breath.
Begin with 3 seconds in.
Exhale for 4 to 5 seconds.
Keep the breath relaxed. Do not pull huge breaths in or push the air out.
Continue for several minutes.
If Level 1 becomes easy, experiment with 4 seconds in and 6 seconds out.
Stop forcing it if you become dizzy, tingly, uncomfortable or distressed.

Safety: breathing exercises should feel controlled and comfortable. If you are pregnant or have significant cardiovascular, respiratory, neurological or other medical conditions, speak with an appropriate health professional before beginning a new breathing practice.

What 18 Years of Professional Sport Taught Me About Breathing

I spent 18 years playing professional basketball in Australia and Europe.

Like most athletes, I trained strength, speed, conditioning, skill and recovery.

What I did not understand early enough was that breathing itself could be trained.

Later, through yoga and my education as an Advanced Breathing Coach and certified Oxygen Advantage instructor, I began to understand how breathing mechanics, breathing volume and nervous-system regulation interact.

That became one of the foundations of Vincere Protocol.

For athletes, breathing is not about trying to remain relaxed all the time.

Sport requires activation.

The skill is being able to regulate your state appropriately — switching on when performance demands it and settling again when the moment allows.

The same lesson applies outside sport.

Breathing Is One Tool, Not the Only One

Breathing is a practical way to influence physiological state, but it is not the only factor affecting HRV or autonomic regulation.

Other important influences include:

sleep
physical activity
training load
illness
alcohol
ongoing psychological stress
relationships and social connection

In Vincere Protocol, we look at breathing through three broad areas:

Mechanics: how the diaphragm, ribs and airway function.
Chemistry: whether ventilation appropriately matches the body’s needs.
Mind and nervous system: how breathing interacts with attention, emotion and physiological arousal.

Slow breathing primarily targets the third area, while breathing mechanics and breathing volume also matter.

Other Ways Breathing and Behaviour Can Influence Your State

Humming, Chanting and Om

Humming naturally extends the exhalation.

Research has also shown that humming can produce a substantial temporary increase in nasal nitric oxide compared with quiet nasal exhalation.

That does not mean humming directly “tones” the vagus nerve, but it can be incorporated into a relaxing breathing or yoga practice.

Social Connection

Feeling safe and connected with other people can influence stress and emotional wellbeing.

This is one reason the social component of a yoga studio can matter as much as the physical practice for many people.

Meditation

Meditation often coincides with slower and quieter breathing.

Breathing is therefore likely to contribute to at least some of the physiological changes observed during meditative practices.

How to Support Autonomic Regulation Over Time

Within Vincere Protocol, we build breathing practice around four simple foundations:

Nasal breathing when appropriate
Light breathing rather than unnecessarily large breaths
Diaphragmatic breathing with gentle lower-rib movement
Slow breathing practised comfortably rather than forced

If you like tracking data, HRV can provide useful information.

There is no single perfect HRV score.

Values vary substantially between people, so the most useful comparison is usually your own trend measured consistently over time.

Using HRV With Athletes

Through Vincere Protocol, I use HRV as one piece of information rather than treating it as a standalone performance score.

If an athlete’s resting HRV trend changes alongside poor sleep, unusual fatigue, increased training load or reduced performance, that information can help guide a conversation about recovery.

But one high or low reading does not tell you everything.

The same applies to everyday students.

Look at trends, how you feel and what has been happening in your life rather than becoming obsessed with one number.

What the Research Shows

Slow Breathing and HRV

A 2022 systematic review and meta-analysis examined voluntary slow breathing and found that slow breathing can increase measures of vagally mediated heart rate variability during practice, immediately afterwards and following repeated training.

This is one of the stronger pieces of evidence supporting the physiological effects of slow breathing.

HRV Biofeedback

HRV biofeedback uses real-time heart-rate information to help a person practise breathing near an individually responsive breathing rate.

A 2020 systematic review reported benefits across a range of psychological and physiological outcomes, although study quality and effects varied considerably.

Does the Exhale Need to Be Longer?

Many breathing traditions use a longer exhalation.

Research comparing equal inhale-to-exhale ratios with longer-exhale patterns has produced mixed findings.

The practical conclusion is simple:

Comfort, breathing rate and avoiding excessive breathing volume are more important than obsessing over the exact ratio.

Can Slow Breathing Lower Blood Pressure?

Slow breathing interacts with the baroreflex and cardiovascular regulation.

Some studies of slow breathing and HRV biofeedback have reported modest reductions in blood pressure.

Breathing exercises should not replace appropriate medical treatment for hypertension.

How Do You Know if the Breathing Exercise Is Working?

You may notice that your breathing becomes quieter, physical tension reduces and your heart-rate pattern becomes more rhythmic.

An HRV monitor will often show larger respiratory-related heart-rate oscillations during slow breathing.

If you feel dizzy, tingly, distressed or feel that you are fighting for air, stop forcing the breathing pattern and return to normal breathing.

A useful reminder is:

Nose. Slow. Low. Light.

Breathe With Us at Raw Power Yoga

At Raw Power Yoga in Albion, Brisbane, breath awareness is integrated into our yoga practice.

Our classes combine movement, breathing and attention rather than treating them as completely separate systems.

You can explore our full range of yoga classes in Brisbane, including:

See the Raw Power Yoga timetable to find your next class.

New students can also try 10 days of unlimited yoga for $48.

For athletes, teams and organisations wanting a dedicated performance-breathing system, visit Vincere Protocol.

Frequently Asked Questions

How does breathing influence the vagus nerve?

Breathing affects cardiac vagal activity and interacts with systems including respiratory sinus arrhythmia and the baroreflex. Slow breathing can increase the size of the heart-rate fluctuations associated with breathing.

What is the best breathing pace for the vagus nerve?

Research often finds strong HRV responses somewhere around 4.5 to 7 breaths per minute. In Vincere Protocol, we commonly begin with 3 seconds in and 4 to 5 seconds out and progress, when comfortable, towards 4 seconds in and 6 seconds out.

Why should I avoid taking huge breaths?

Slow breathing does not need to mean large breathing. If each breath becomes excessively large, total ventilation can remain high. The aim is comfortable, controlled breathing rather than forcing maximum inhalations.

What are the benefits of slow breathing?

Research shows that slow breathing can increase vagally mediated HRV during practice and may support relaxation and autonomic regulation. Research into repeated practice also suggests potential benefits for outcomes such as stress and anxiety, although effects vary between people and studies.

How often should I practise?

A practical starting point is approximately 5 to 10 minutes once or twice a day. Comfortable consistency is more important than forcing long sessions.

Can slow nasal breathing improve heart rate variability?

Slow breathing commonly increases HRV during the practice because breathing and heart rate become more strongly synchronised. Long-term changes in resting HRV should be assessed using consistent resting measurements over time.

Does a breath-hold test measure vagal tone?

No. A comfortable breath-hold test can provide information about your response to breath holding and respiratory discomfort, but it does not directly measure vagal tone or heart rate variability.

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