The "Why" Behind Nasal Breathing

Updated: May 12, 2020



I was first introduced to this topic when I was reading through Cal Dietz' work years ago. He frequently referenced conditioning methods involving taping his athlete's mouth shut. I could't help but think:

Couldn't this be dangerous?

How important might this be if he's taken the time to convince all these kids to tape their mouth shut?

I've got to learn more about this.

Luckily, Cal referenced a great resource to learn more about the topic, The Oxygen Advantage by Patrick McKeown. I immediately purchased it and read through it in a matter of days. It's truly a great read that requires no scientific background to grasp and understand. I would recommend it if any of the below details or future blog posts interest you.


The premise comes down to the way that we tolerate carbon dioxide (C02) in our system. As you may know, our body relies on our respiratory system to bring in oxygen and expel C02. What is lesser known is that C02 is the most relevant part of that equation when it comes to our breathing and our training.


Oxygen is extremely abundant in our blood with a normal blood oxygen saturation of 95-100%. Personally, mine has always measured at 97-99%. A lot of phones have a blood oxygen saturation measurement tool and you can test yourself. Try testing at rest then begin a high intensity workout. Are you able to drop the measurement 1-2%? You may be shocked at how much effort is required to make such a small change. Alternatively, you could try doing a series of breath holds to see what changes that makes. Again, you may be surprised how little it changes. (I cannot attest to the accuracy of the sensors built into phones but it is an easy way to experiment).


C02, on the other hand, is what your body is on high alert for. The mechanism in your brain that forces you to breath against your conscious will when holding your breath is also the mechanism that increases your breathing rate when you exercise. That mechanism is triggered by high C02, not low oxygen. Now, consider what the limiting factor to your endurance is. When you play your sport or go for a long distance run is it the muscles in your legs that get so sore you can't continue, or is it your breathing that gets so heavy you have to slow down? Chances are it's the later. Therefore, one of the best things we can do for our aerobic fitness and sport endurance is increase our tolerance to C02. In other words, delay the mechanisms in our body that freak out in response to elevated C02 levels.


This brings us to the root of the issue, our daily breathing habits. Mouth breathing during the day and mouth breathing while you sleep cause us to over breath. Most people do one or the other, if not both. Remember, C02 is the most relevant factor. When we breathe through our mouth we are breathing too much air at too fast a rate. This doesn't change our blood oxygen saturation because under normal conditions we are already maxed out (do you really need to get from 98% to 99%? You wouldn't notice this change anyway.) Instead, by over breathing you're emptying your blood of C02. When you do this day after day you naturally decrease your bodies tolerance to high C02 levels because there's never any exposure to significant C02 in the blood. Heavy breathing causes low C02 tolerance, which causes us to breathe heavier and the feedback loop continues.


Here lies another interesting issue; when C02 levels are low we actually limit the availability of oxygen in our cells. When oxygen travels through our bloodstream attached to red blood cells there is a positive correlation between C02 levels and the oxygen's ability to separate from our red blood cell and enter our tissues. In other words, as C02 levels rise oxygen is more readily available to the cells in our muscles, organs, and other vital tissue cells. As C02 levels decline, as with over breathing, oxygen clings to our red blood cells harder making it functionally useless. This leads to another counter-intuitive fact, breathing less causes more oxygen to enter our tissues where we need it most.


Let's move on the the practical side of things. What can you do today to begin increasing your C02 tolerance?


Disclaimer: The recommendations below are meant to be educational in nature only. It is up to you to consult a physician before attempting any of the exercises/techniques and consider any conditions you may have (ex: asthma) that may compromise your ability to safely participate. With that said, these techniques are widely considered beneficial for asthmatic symptoms (I may or may not have helped someone with severe asthma with some of these principles). Be smart, be safe, and seek proper supervision/guidance.


You can begin by testing your BOLT (Blood Oxygen Level Test) Score. Here's the protocol:

  1. Rest up to 10 minutes before testing to ensure an accurate resting measurement.

  2. Take a small/natural breath in followed by a small/natural breath out. Do not breathe in or out too deep here.

  3. After your small breath out pinch your nose and hold your breathe. Use a timer to track duration starting from the breathe hold.

  4. Release your nose and stop the timer at the first sign of "air hunger." This is represented by small muscular contractions in the torso or neck, or the first strong desire to breathe. Do not surpass these signs, both for safety and for the accuracy of the measurement. Using pure willpower to continue would be considered cheating the test.

  5. After releasing your nose take a breath in through your nose. This should be a relaxed breathe that's not too deep. Aim to return to a normal breathing pattern immediately.

Now, measure your results against the benchmarks. If you were 20 seconds or less, don't worry, you're in the company of most of the population. It also means you will see huge improvements in your fitness and performance and if you improve that number. If you were 40 seconds or more, congrats! You're already at the goal that Patrick McKeown sets as the benchmark to reach.


Here's some tools to use to increase your score:


Control What You Can Control

During the day be mindful of your breathing. If you're sitting or standing at rest you should absolutely be breathing through your nose. To take it a step further, maintain nasal breathing when walking or doing light physical activity. This may be a shocking challenge for many.


Control What You Can't Control

What's the one time you can't consciously control your breathing? When you sleep! If you snore, drool, or wake up with a dry mouth it's likely that you switch to mouth breathing while you're asleep. Luckily there's a simple fix. I mentioned at the beginning of this post that my first introduction to this idea was Cal taping his athlete's mouths shut. That's right, you can sleep with some tape on your mouth. I use this tape from Nexcare. It holds strong enough to last through the night for me, but I have no doubt if I were to need to open my mouth (say, hypothetically, a runny nose blocked my air) the tape would release without my hand. It also causes no pain when pealing off!


The "Nose Unblocking Exercise"

This is very similar to the BOLT score test, except you're adding walking. Take a small breathe in followed by a small breathe out then hold your breathe. Count how many steps you can take before "air hunger" (see above) sets in then resume normal breathing until air hunger dissipates. Avoid the urge to breathe through your mouth unless necessary. Rest for about a minute then repeat again. Try 4-5 rounds a day.


Stay tuned as I will be sharing ways I've been using these principles in my own training on my Instagram and in future blog posts.