Is Nasal Breathing The Best In All Situations?

Have you ever paid attention to how you breathe?

Do you breathe through your nose or your mouth?

In what situations do you breathe through your nose or your mouth?

You might be asking yourself….

“Why does it matter how I breathe, the main goal is to make sure I am getting in enough oxygen, whether I do it via my nose or mouth, who cares?”

If you are thinking that, you are 100% correct (well mostly), the ultimate goal is not to die and as long as you breathe you are avoiding that.

However there is a difference between surviving and thriving, and I would make an argument that by breathing through your mouth you are surviving, but you likely are not thriving.

Why do I say that?

Breathing through your mouth can negatively affect you in a variety of ways. I covered many of the negative effects in this post, which I will summarize below.

  • Breathing through your mouth causes your diaphragm to become weak and can result in poor posture. This poor posture is associated with emphysema, asthma and other respiratory problems.
  • Breathing through the mouth is associated with being in a stressful situation (imagine running from a tiger or bear). When we breathe through our mouths even in non-stressful situations our monkey brain still thinks we are under some kind of stress. This results in a chronic stress signal which can have a variety of negative health effects.
  • Breathing through the mouth while sleeping can also cause a disruption in our sleep, and sleep is a cornerstone of our health.

On the other hand breathing through the nose has been shown to have positive health benefits.

  • Increase nitric oxide production[1] which is important for heart health because it dilates blood vessels leading to lower blood pressure.
  • Humidifies and warms the air, making it easier to breathe (try nasal breathing when going for a run on a cold day to see the impact for yourself!) [2]
  • It can also filter the air and reducing pathogens and bacteria entering your body [3].

Given this information it seems like nasal breathing is the way to go and we should probably be doing it all the time, right?

For the most part I think this is true. I do think that we should be trying to breath nasally as much as possible. I think this is especially true when we are sitting, standing, sleeping, or any other time you are not moving.

However, like nearly everything in today’s world people hear something is good and it is treated as a MUST DO AT ALL COSTS AT ALL TIMES.

Personally I think we evolved to breathe through our nose AND our mouths for a reason. There are very few examples where a physiological function is kept around in the human body for no good reason, so breathing through our mouth should serve a purpose.

I believe that the reason we can breath through our mouths is to deal with an imminent threat, where we need to physically exert ourselves at a near maximal effort or perish.

Remember when I said breathing through our mouth signaled that we are under stress? That is because we had to breathe through our mouth when we had to escape a dangerous situation while running at near maximal effort. When the body needs to exert itself at that intensity, “optimal” goes out the window, it’s all about survival

This applies to a variety of physiological functions, including how we breathe.

Why is it more efficient to breathe through our mouths during a survival situation?

It all comes down to removing carbon dioxide from the body.

Contrary to popular belief the most important part of breathing is not taking in oxygen rather it is removing carbon dioxide. Carbon dioxide is a poison to the human body and it’s the removal of it which causes us to take a breath.

When we are exerting ourselves at maximal effort carbon dioxide is produced at a greater rate and the most efficient way to remove that carbon dioxide is via the mouth, not the nose.

However because of the popularity of nasal breathing and the benefits it has you may see people suggest that nasal breathing even at maximal effort is superior.

Obviously today we are not running from many predators, but we do see people maximally exerting themselves physically during exercise. I have seen many people suggest that you should be nasal breathing even during maximal effort.

I even came across a study recently that showed there was not difference in power output or performance measured during anaerobic exercise when breathing through the nose versus breathing through the mouth [4].

While I don’t dispute the outcomes of this study and the conclusions the researchers reached, I would like to put some context around these results. First, if you dig into the methods section of this study you see that participants performed exercise for 6 different durations breathing nasally and via the mouth.

They did an all out effort on a cycle ergometer for 5, 10, 15, 20, 25, and 30 seconds.

For most athletes, breathing through their nose up to about 15 seconds even at an all out pace should not be challenging at all. Now I would say that 20-30 seconds may not be easy for people, but it’s also not terribly long either. This is reflected in the study as we see at 25 and 30 second efforts the group that was breathing through their nose had statistically significantly higher heart rates.

On the plus side when nasal breathing participants tended not to hyperventilate.

At the end of the day though what mattered most, performance, was not significantly different, so that means we should be nasal breathing during maximal exertion!

Not so fast.

What I would like to see these researchers do is extend the duration…what happens at 45 seconds, 1 min, 2 min, 3 min?

I am willing to bet that as time goes on the nasal breathers will be at a significant disadvantage to those that mouth breath.

However if I could design this study I would add a third group in the mix. I would have a group that trained using more of a “gear system” that the folks at Shift/Adapt promote.

Here is how the gear system works…

You breathe nasally only up to an intensity you can manage, then you breathe nasally for the inhale, and exhale through the mouth, and then finally once you get to an intensity that is high enough you breathe in and out with your mouth.

So the study would have 3 groups, nasal only for all durations, mouth only for all durations, and then the group that used the gear system that transitioned from nasal only towards mouth only.

My guess would be that as duration increases that the gear system group would outperform the nasal only or mouth only groups because they would get the best of “both worlds”.

In fact I use this gear system with my own training and with my clients.

As always I like to give people practical advice that they can actually use so here are some things you can do to leverage both nasal and mouth breathing.

First thing to do is to focus on breathing nasally while you are going about your day to day activities.

Rather than try to explain how to go about doing that, here is a great article and video by Zac Cupples that has some great tips for implementing this.

On the exercise piece I always start with aerobic, very easy, zone 2 cardio work. The goal when doing this type of exercise is not only to keep your heart rate down, but once that is fairly easy to do then exercise breathing only through your nose. At first this may be quite hard, and you might only be able to breath nasally for a short time before having to breath through your mouth. If that is the case don’t worry about it, but instead I would suggest you employ the gear system.

Once you can no longer breathe through your nose, breathe in through your nose and out through your mouth and see how long you can sustain that. If you eventually feel like you need to breathe through your mouth that’s OK.

The goal though is to increase the amount of time you can breathe through your nose exclusively. It will take time so don’t give up. Some days will be easier than others, so try not to get down on yourself. Stick with it, these adaptations are not overnight, but you should notice things getting better.

Once you can do your easy aerobic zone 2 exercise breathing from your nose, it’s time to practice the next gear, nasal in mouth out. For this you will likely need to increase the intensity, you will want to be somewhere between your easy aerobic intensity but less than maximal intensity. This is what I refer to as the “black hole” of intensity. To learn more about this intensity you can read this blog post I did on the topic.

When you are at this intensity you are going to try and do your workout breathing in nasally but exhaling through your mouth. Again, to start this might be hard and you might not be able to last the entire duration breathing this way, that’s OK. Just keep trying to increase the duration you can maintain that breathing pattern.

When it comes to putting the pedal down to the floor, now is the time to breathe through your mouth. However I still advocate the gear system at these times.


In the study above where they were testing nasal versus mouth breathing, they showed the nasal breathing group was able to avoid hyperventilation. This is certainly a good thing as it can have negative effects on your performance the longer you hyperventilate. So if you can delay that from happening by nasal breathing, and then breathing in through your nose and out through your mouth, the better it will be for you, especially as you are asked to sustain that intensity.

One other question you might have is how to breath while resistance training?

My opinion is to again leverage the gear system. The difference is that intensity can be hard to judge because it’s dependent on the weight and the number of reps you are doing. In general though the longer you are actively lifting the weight the harder it’s going to be cardiovascularly so it’s going to become tempting to breathe through your mouth. Again it’s beneficial to try and delay the mouth breathing as long as possible. If you do end up breathing through your mouth that’s OK, but what I would suggest in this situation is to pay close attention to your breathing during your rest between sets. You want to return your breathing to through your nose exclusively as soon as possible. This should lower your heart rate and send a signal you are under less stress, getting you set up for the next set.

You probably never thought that the way you breath could be so impactful. The truth is, like the many things I speak about, we are just trying to fix ancestral mismatches. We shouldn’t really need to think about how we are breathing, but our modern environment has dysregulated our breathing habits, so now we need to do some work to correct it. The good news is that it is not hard to correct, it just takes a bit of conscious oversight for a while. Eventually though breathing through your nose will become your default. If you would like to get more practical advice to help correct ancestral mismatches to help you reach your goals sign up for my newsletter using the form below. Each week I provide down to Earth practical advice you can immediately incorporate into your daily life to get you where you want to be!

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  1. (n.d.). Decreased pulmonary vascular resistance during nasal breathing. Retrieved January 23, 2023, from
  2. (n.d.). [The influence of breathing mode on the oral cavity] – PubMed. Retrieved January 23, 2023, from
  3. (2020, May 6). Could nasal nitric oxide help to mitigate the severity of COVID-19?. Retrieved January 23, 2023, from
  4. (2017, July 1). Effects of Nasal or Oral Breathing on Anaerobic Power Output and …. Retrieved January 23, 2023, from

2 thoughts on “Is Nasal Breathing The Best In All Situations?

  1. In the paragraph directly above the first bar graph, I think there is a mistake. It looks like the group that breathed through their NOSE had the higher heart rates. Or did I read the graph wrong?

    1. No you are right Susan! Thanks for catching that! I updated the post.

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