“Take a Deep Breath” Is Bad Advice!

February 17, 2021


Dr Sven Hansen

Taking a deep breath will create arousal, anxiety, distress, and reduce CO2 even more. “Experts”, from physicians to coaches, default to this faulty recommendation.The science of breathing demonstrates how this advice is scientifically and practically wrong. Rather, apply the correct practice to counter distress, calm, focus and connect to reality. This is how you prevent and beat "burnout".

Basic science to understand:

1. Heart rate changes with breathing. Inhalation accelerates your heart. Exhalation – particularly when sustained longer than inhalation – slows your heart.2. This is called sinus arrhythmia or heart rate variability. When it follows a sine curve it is a very reliable marker of good health and reduced risk (1).3. Exaggerating inhalation engages chest muscles shortening and accelerating the breath. This causes CO2 to drop and is part of hyperventilation syndrome (2).4. Hyperventilation happens when anxious and, if sustained, leads to low CO2 (carbon dioxide) and a range of symptoms including anxiety, pounding heart rate, chest pain, light-headedness. It is estimated to affect 10-30% of otherwise healthy people and can lead to hospitalisation.5. Arousal, with increased heart rate is associated with the sympathetic nervous system (SNS) and calm, with lower heart rate is associated with the parasympathetic nervous system (PNS, mediated by the vagus nerve) and called vagal tone or vagal brake (3).6. Neck and upper chest (secondary) muscles ventilate the upper lung. These are only required in extreme situations of physical effort7. Diaphragm and intercostal (primary) muscles ventilate lower lung. These muscles facilitate heart rate variability, calm and good health.

When you take a deep breath …

You will activate your chest and neck muscles, trigger the sympathetic system, strain your neck muscles, accelerate your heart, and activate a state of increased arousal. The vagal brake is switched off and you can compromise both muscle and brain function as CO2 falls.Advice to “breathe in through the nose” further strains secondary breathing muscles. Adding “out through the mouth” causes the loss of CO2 and a shorter exhalation. If you continue to take this advice you can drive your physiology into an acute or chronic case of hyperventilation.There is no point in voluntarily taking a deep breath. Your neurophysiology takes care of it in the background. Remember the last time you dived under a big wave!

Tactical calm is exhalation…

The first step to calm and focus is to exhale voluntarily through the nose. As you lengthen the outbreath, the diaphragm relaxes, domes upward and the vagus (PNS) nerve activates. Heart rate slows, muscles relax, and blood returns to the prefrontal cortex and empathy circuits.Whether on stage, in battle, on the court, needing to connect or be creative, experts in all fields have to master this simple technique. Below is a short demonstration of heart rate variability showing these effects.


Figure 1. Heart rate changes through three conditions:

  1. Concern about conflict in a family (heart rate accelerates from 55-60 up to 70 bpm)
  2. Advised to take three deep breaths (irregular pulse, wild acceleration 50 to 70). It counters the natural calming that was taking place prior to advice.
  3. Slow exhalations creates high amplitude heart rate variability and calm

For more on the physical, emotional and mental effects of breath and vagus nerve read Calm, Control & Connect, December 2019.

Let’s get practical…

Whenever you notice agitation, worry, fatigue and any distress symptom, simply exhale for 5 or 6 seconds with a pause at the end. Then breathe slowly into the lower ribs and abdomen through the nose for 3 or 4 seconds.Repeat as needed.

Tactical (square) breathing

All special forces are now taught a variation of this which involves: 4 seconds exhale, 4 seconds hold, 4 seconds inhale and 4 seconds hold. This is used to get combat ready (condition yellow) and effective by being calm, focused an connected.Live webinar April 2020 with Tania Clifton-Smith, Brad and SvenNothing new here folks! The yogis have recommended this explicitly for over 2000 years. A simple audio for guided practice can be found here: Breathe out slowly!I highly recommend reading Breath by James Nestor (Penguin, 2021) and for those wanting to stretch adaptation, The Wim Hoff Method by the iceman (Penguin, 2021)(1) Matthew Mackinnon, Psychology Today.(2) Dinah Bradley, Family Doctor.(3) Sven Hansen, Breath, Revive, Connect: Insights.

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