By Dr Raymond Lau, Chiropractor



Breath Part II — How Does Breathing Affect My Body? 

(if you missed part 1, catch up here)

There are two ways air can enter into our lungs, either through our mouth or nose. However, they are designed to do different things. Our mouth should be mainly used to eat, drink and talk. We can occasionally use our mouth to breathe but it should be reserved for higher intensity exercise when we can’t maintain nasal breathing. On the other hand, our nose is a crucial and vital organ that is designed for us to breathe optimally (and smell).


By breathing through our nose, it can perform the following functions:

  • Filters particles (i.e. germs and bacteria) and pollutants from the air
  • Humidifies, and heats the air for easier and better absorption of oxygen.
  • Increases oxygen uptake by 10-20% from greater resistance vs mouth breathing.
  • Creates a boost of Nitric Oxide (NO) — a very important molecule that I will go into a bit more detail later.
  • Improve athletic performance by helping aerobic/anaerobic performance, reduction of lactic acid build-up and fatigue.

In contrast mouth breathing can cause:

  • Dry mouth (which can lead to greater infections) causing bad breath, dental and gum decay (from increased acidification and altered bacterial flora in the mouth)
  • Upper chest breathing — which in turn can cause forward head posture and restricted neck movement
  • Greater incidence of sleep apnoea and snoring — causing increased fatigue
  • Introduction of unfiltered and cold air into the lungs — potentially increasing risk of illness
  • Changes to the structure of our face! — long, narrow face and mouth, and dental occlusions

Carbon dioxide and nitric oxide helps with increasing circulation and the delivery of oxygen into our cells (as discussed in Part I), improving immune function, and has been found to play a significant role in cardiovascular health. In fact, a slight reduction in carbon dioxide in the blood can cause an increase in heart rate. In addition, nitric oxide is an essential and powerful stimulus to tell our blood vessels to relax and dilate, while reducing cholesterol and the build-up of plaque in our blood vessels preventing the risk of heart attack and stroke. The great thing is that we can increase the amount of nitric oxide production in our body by including slow nasal breathing and regular moderate physical exercise as it is produced inside our nasal sinuses and blood vessels. Breathing slowly through the nose allows it to be picked up and carried around our body through our lungs and blood.

(One Nobel Prize winner wrote a book titled ‘No More Heart Disease: How Nitric Oxide Can Prevent – Even Reverse – Heart Disease and Strokes.’)

How to change your breathing rate

Interestingly, the rate at which we breathe also has an effect on our body. In Breath Part I, I mentioned how over-breathing can be brought on by exhaling too much CO2 and taking in too much air with each breath. But over-breathing can also be caused by increasing the rate. Changing our breathing rate can determine if our sympathetic (fight-or-flight) or parasympathetic (rest-and-digest) nervous system is more active.


When we are stressed, our sympathetic nervous system — fight-or-flight response — becomes more active making us feel overstimulated and anxious/stressed. Give this a try. Take rapid and shallow breaths for a minute. You may notice one or a few of these responses: increased heart rate, increased anxiety/stress, upper chest and neck breathing, difficulty concentrating, light-headedness. Now imagine if your flight-or flight response was active all day! This could have compounding effects on your body. Some of these effects could show up as: increased fatigue, headaches, muscle tightness, increased resting heart rate and blood pressure. The good thing is that we can change that! By simply breathing slower!

When you slow down your breathing and extend your exhales your rest-and-digest system starts to become more active. By slowing down our breathing rate and normalizing the amount of air inhaled (5-6L/min)— blood flow to the brain increases, heart rate and blood pressure decreases, and calmness ensues. Which is why when people practice meditation or even yoga they start to feel really relaxed. For example, a group of researchers found an immediate improvement in heart rate and blood pressure after a group of young adults practiced the 4-7-8 breathing (1).


To get a sense of how much air we should be inhaling with each breath, the traditional Chinese practice of Taoism and concept of Chi (Qi), and Indian yoga echoed the importance of effortless breathing. Effortless breathing is described as breathing so softly that you don’t feel yourself breathing. It should feel as though the hairs in your nose remain motionless or if you were to put a feather under your nose it shouldn’t move when you breathe. When you initially practice effortless breathing, it can feel very nerve wracking and feel like you aren’t getting enough air. However, with practice (for a few minutes a couple times a day) your body will adapt to it and become easier and effortless.


*Disclaimer* — please consult with a medical practitioner before starting a breathing program, especially if you have a current cardiovascular or respiratory condition, and if you are pregnant.


Try this 4-7-8 breathing exercise – made popular by Dr. Andrew Weil. (I personally like doing this lying down with my eyes closed)

  • Inhale through the nose to a count of 4
  • Hold for a count of 7
  • Exhale completely through the mouth to a count of 8.
  • While doing this exercise, place the tip of your tongue against the roof of your mouth behind your upper front teeth.

If you complete this cycle at least 5 times you should find that your body starts to enter a state of deep relaxation (like your entire body starts to float on a cloud). I find it very useful for patients who are extremely ‘wound-up’, experiencing tight muscles, or just really stressed.

To watch my video demonstrating this technique on our youtube channel, click here.

If you would like to learn more about breathing less and what exercises you can do to improve your breathing, feel free to book a consultation with me.

In Part III, I will be discussing how breathing properly can help athletic performance and perhaps help with your mobility.



  1. Allen R. The health benefits of nose breathing
  2. Vierra J, Boonla O, Prasertsri P. Effects of sleep deprivation and 4‐7‐8 breathing control on heart rate variability, blood pressure, blood glucose, and endothelial function in healthy young adults. Physiological Reports. 2022 Jul;10(13):e15389.
  3. Nestor J. Breath: The new science of a lost art. Penguin; 2020 May 26.
  4. McKeown P. The Oxygen Advantage: The simple, scientifically proven breathing technique that will revolutionise your health and fitness. Hachette UK; 2015 Sep 15.