This week I’ve been enthusiastically digesting the book The Oxygen Advantage: The Simple, Scientifically Proven Breathing Techniques for a Healthier, Slimmer, Faster, and Fitter You. It’s eye-opening and counter-intuitive in many ways. I thought I knew how to breathe, but it turns out I didn’t.

Someone recommended this book to me earlier this year, so I added it to my audiobook queue. I wondered what I’d learn about breathing from nine hours of audio that I didn’t already know. I figured it would just be reinforcement of some relaxation techniques and meditative practices that I was already familiar with. Nope, that’s not what it’s about.

What I didn’t expect was that it would challenge what I thought I knew about breathing. This book encouraged me to experiment with breathing differently – not just during some deliberate breathing practice but all day, including during exercise.

It’s too soon to share long-term results since I’m only a couple of days into this type of experimenting, but I like to share what I’m learning along the way since I think there’s value in the newbie perspective.

Shallow Breathing Is Better

I always thought that deep diaphragmatic breathing was good. Breathe slowly and deeply. Sometimes I’ve heard “in through the nose and out through the mouth,” at least for meditative breathing.

Nope – all wrong. Apparently it’s healthier to breathe shallowly, so shallowly that it barely looks like you’re breathing at all. Just inflate the lungs a little, not deeply. And pause for several seconds between breaths.

Perhaps you believe that if you take deeper breaths, it will oxygenate your blood more. Lots of people believe that. So did I. It’s a myth. Breathing more deeply won’t oxygenate your blood any more than breathing shallowly.

I tested this for myself using the new Apple Watch’s blood oxygen sensor, which takes 15 seconds to test each time. Normally my readings are 96-100%. If I breathe deeply, it doesn’t get any better. And when I slow my breathing down even more and breathe as shallowly as I can, the readings are still in the same range.

Is 100% the best result for this test anyway? No, a slightly lower reading is actually better. You want your cells taking the oxygen out of the blood, so if you’re at 100%, it may mean that your cells aren’t absorbing the oxygen as well as they could be. The high 90s are apparently best.

Taking in enough oxygen through breathing isn’t the issue. Your lungs are really good at taking in oxygen, unless you’ve damaged them through smoking or coal mining. If you’re already close to 100%, taking in more oxygen isn’t going to get you any higher. The blood is already as full as it should be.

What matters here is getting your cells to absorb oxygen from the blood more efficiently. This depends on the level of carbon dioxide in the blood, not on the oxygen level. Whether your blood is at 96% or 99% oxygen capacity, you’re unlikely to notice a difference because anywhere in that range, your blood still has plenty of oxygen for your cells. So your blood oxygen is like a cup that’s always full. The real question is how fast your cells are drinking from that cup. Trying to overfill the cup won’t get you anywhere since it’s never low or empty (or you’d be dead).

With more CO2 in the blood, cells naturally take in more oxygen. Shallow breathing doesn’t affect blood oxygen levels, but it does increase the amount of CO2 in the blood. And apparently there are measurable health and fitness advantages to building up your CO2 tolerance, so your blood is higher in CO2 and your cells absorb oxygen more efficiently. Basically you’re helping your cells absorb more of a key resource they need, so your brain and body will work more efficiently. Help your cells at the micro level, and you’ll likely see benefits at the macro level. This sounds reasonable to me as it’s explained in the book, but of course it invites personal testing to know for sure.

When you hold your breath, what makes you feel that strong urge to breathe again? You may think that it’s your need for more oxygen. It isn’t. It’s actually the urge to get rid of the CO2 that’s building up.

Even while you hold your breath, there will still be plenty of oxygen in your blood being delivered to your cells for a good while longer, but the carbon dioxide buildup feels incredibly uncomfortable, and that increasing CO2 makes you want to breathe again.

As it turns out, developing a higher tolerance for CO2 is advantageous. While CO2 is a waste product, it actually does some good if you can handle higher concentrations of it, including potentially reducing depression and improving focus. And that’s because CO2’s presence encourages cells to take in more oxygen, as previously noted.

I wasn’t aware of this before reading this book, so this simple reframe motivates me to experiment with it to see how breathing differently affects me physically, mentally, and emotionally. I love these types of growth experiences where I learn some new tidbit of information, and then I can dive into some fresh experimentation to see where that information leads in terms of results.

Consequently, this week I’ve begun practicing with making my breathing slower and more shallow, such as while I sit at my desk and work, challenging myself to lean into a less comfortable way of breathing until I get comfortable with it.

Take a Simple Breathing Test Right Now

Here’s a simple breathing test you can take right now. It’s called the BOLT test (Body Oxygen Level Test). It will take less than a minute. You just need a timer or stopwatch – some way to measure seconds. I’m sure you can Google to find an online timer if necessary.

Here’s what to do:

1. Stabilize your breathing if you’ve been moving around.
2. Breathe in once normally and then out normally, through your nose.
3. After your out-breath, pinch your nose with your fingers to prevent any extra air from getting in, and keep your mouth closed. This is when you begin timing.
4. For this next step I’ll quote the exact wording from the Oxygen Advantage website: “Time the number of seconds until you feel the first definite desire to breathe, or the first stresses of your body urging you to breathe. These sensations may include the need to swallow or a constriction of the airways. You may also feel the first involuntary contractions of your breathing muscles in your abdomen or throat as the body gives the message to resume breathing. (Note that BOLT is not a measurement of how long you can hold your breath but simply the time it takes for your body to react to a lack of air.)”
5. When you feel that first definite desire to breathe, release your nose, take a normal breath, and note how many seconds have passed. Keep breathing normally afterwards.

Your BOLT score is the number of seconds you timed.

If you do this right, you should be able to breath calmly afterwards. If your breathing is strained or rapid after you release your nose, you held your breath for too long. You want to breathe when you feel the urge to breath, so it’s not a contest to try to hold your breath for longer than that. Keep your ego out of the testing process, and seek the truth.

I suggest you do this test now if you can before you continue reading. I’ll wait. 🙂

When I do this test, I’m not always sure about the exact second when I feel that definite desire to breathe because it comes on semi-gradually. So there might be a 3-4 second range where I’m not really sure if I’m there yet. But I figure that even if I’m off by +/- a few seconds, I’ll still get some worthwhile info from the measurement, and I can also see if I’m improving over time. I might not notice a 3-second improvement, but I’d surely notice a 10-second gain.

According to the book, a typical score is around 20 seconds, and the ideal score to build towards is 40 seconds. If you’re below 10 seconds, you likely have some health challenges that you probably already know about. Apparently you’ll notice health improvements with every 5 seconds of improvement in your score. The book goes into detail on those improvements, along with many exercises for how to improve.

The first few times I tested my BOLT score earlier this week, I kept landing in the 13-17 second range. Yesterday I tried it again after breathing calmly and shallowly for a while, and I got 19-21 seconds. I just tested it now this morning, and I’m currently getting 15-16 seconds. So my scores aren’t hideous, but they aren’t great either. Awesome! That means this is likely to be a growth experience. Now I’m extra curious about what would happen if I trained up to 40 seconds.

Nose Breathing While Exercising

Do you breathe through your nose or mouth while exercising?

I’ve always been breathing through my mouth. Even while walking, I usually breathe through my mouth unless I’m going fairly slowly.

I can’t recall ever doing running, cycling, elliptical, weight training, martial arts, tennis, or any other kind of sustained exercise while breathing through my nose.

If I tried to breath through my nose while exercising, I’d feel like I wasn’t getting enough air. So I always breathe like a doggie. 🙂

The possible exception is yoga, but only if it’s a very yin style with long, slow stretches. If I’m doing a form of yoga that gets my heart rate up, including hot yoga, then I’ll be breathing through my mouth for at least part of it.

When I’m not exercising, I normally breathe through my nose, but even then I might sometimes catch myself breathing through my mouth, depending on what I’m doing.

According to the book, I’ve been doing it all wrong. Supposedly it would be wise to retrain myself to breathe through my nose all the time, including during exercise. I wondered if I could even do that.

I love running and typically run 5-6 miles most mornings, sometimes more. I always breathe through my mouth when I run though. Breathing through the nose doesn’t seem like it would give me enough air. But apparently I don’t need as much air (or oxygen) as I might think. Instead I need to develop a higher tolerance for CO2. Breathing through my mouth all of these years has likely made me extra sensitive to CO2, so I breath through my mouth while running to get rid of CO2 quickly.

Feeling like I can’t get enough air while breathing through my nose is actually the discomfort of CO2 buildup. It’s not the need to take in more oxygen. Fascinating!

I wondered how to retrain myself to run while breathing through my nose. I didn’t see any way that I could just immediately switch over and still be able run for an hour or more. I figured I might only last a minute the first time I tried it, and then I’d be choking for air like that scene in Total Recall.

So how to train if I can’t just switch right away? Do I try doing intervals, switching between mouth and nose breathing? I figured I could do that and then extend the intervals till I could fully sustain nose breathing.

Fortunately the book had another suggestion, which is to do only nose breathing but go slower, and then drop down to walking if necessary. So it can still be done like interval training but between walking and slow running, not between mouth and nose breathing. Okay, I could try that approach.

This morning I decided to see what would happen if I tried breathing through my nose. The book notes that warming up adequately makes it easier. So I walked for 15 minutes to warm up slowly, breathing through my nose the whole time. Even that felt a bit awkward, but I’ve been practicing walking with nose breathing for a couple of days now, so it’s getting easier. Now I can walk with nose breathing sustainably if I don’t go too fast, even though it still feels a little weird and unnatural.

After 15 minutes of walking, I switched to running at an easy pace. It felt like my body was confused right away. I struggled to coordinate a good rhythm between my steps and my breathing. I didn’t know how big or fast my breaths should be. It was pretty obvious that my breathing wasn’t in very good sync with my running.

I made it 1:44 before I had to drop down to walking again to catch my breath, so not even 2 minutes. But I stuck with nose breathing throughout and didn’t open my mouth. I stabilized my breathing with a few minutes of walking and decided to try again. I figured I’d make a game of it and see if I could keep beating my previous best each time I tried. Could I beat 2 minutes this next time?

The second time was better – still awkwardly unnatural at first, but I began falling into a better rhythm. I ran with nose breathing for 5 minutes straight. I probably could have gone longer, but I thought it wise not to push too far too quickly. I figured I’d give my brain some time to process the learning experience more gradually.

I did a few more minutes of walking, still nose breathing. Then I ran for 10 minutes with nose breathing – starting to get the hang of it. That’s more than I expected to be able to do in my first training session of this type.

Then a little more walking, and for the final stretch I ran for 31:30, which was closer to 30 minutes of actual running since I had to stop at a traffic light to cross the street at one point near the end. Amazing!

I was surprised that I could do that in just my first training session with this approach. I don’t think I’ve ever run for 30 minutes straight while breathing through my nose – like never in my life. Somehow I just learned to exercise while breathing through my mouth, and I never thought that might be a problem.

Additionally during the last stretch, I also wove in some breath holding, which is supposed to help even more with the training effect. Now and then I’d hold my breath while running for 10-12 paces, so that’s just a few seconds each time. Then I’d resume normal breathing, always through my nose the whole time. I did about 12-15 of these breath holds during the 30-minute segment. It took me 2-3 breaths to stabilize my breathing after each hold. The hardest were when I was running uphill.

Eventually I’d like to build these breath holds to 20-40 paces, which should be doable as I get more efficient.

I’ll keep training with this approach to see where it leads since I’m super curious about it. I imagine that I could do a 60-minute run with nose breathing very shortly, maybe even tomorrow, since I just did half of that this morning. The key seems to be giving my brain and body enough practice to learn to sync breathing and movement, so I get into a nice rhythm. The rhythms for exercising with nose breathing and mouth breathing are different. I think I figured out one version of a sustainable rhythm today, but I’ll likely need more time to learn the rhythms for different conditions like faster pacing and doing hills. I think it’s just a matter of keeping my mouth closed while running, and my body will figure it out.

Note that I did today’s run at a slower pace than usual, so my heart rate was on the low side for cardio – only in the 120s most of the time (124 bpm average, 140 max). It may take a while longer to rebuild the pacing with sustainable nose breathing.

I’m especially curious if I can eventually run faster while breathing through my nose than I could through my mouth. That seems impossible if I’d need more air to run faster since I can’t take in as much air through my nose. But now that I know that this is really about CO2 tolerance, not oxygen intake, I have to wrap my mind around the idea that it’s very possible that I could run faster while taking in less air than before. That idea makes my brain do a double-take, but it will be fun to find out. That would be freakishly weird – and cool – to discover that I might actually run faster with nose breathing.

For now I revel in the challenge of exploring a different way of running. After decades of doggie style, I’m ready for a fresh approach. For the next few weeks at least, every run will seem different than before, even on familiar routes.

I also have to relearn how to do other exercises with nose breathing. And even when I was doing nose breathing, I have to practice how to take shallower breaths with longer pauses between breaths. I practiced this while doing 40 minutes of yoga last night, and I noticed that my heart rate was lower than usual… as low as 52 bpm on some floor stretches. I think that’s the lowest heart rate I’ve ever seen during a yoga session.

If any of this fascinates or challenges you, I encourage you to read The Oxygen Advantage. See if it inspires you to retrain yourself to breathe differently and to improve your BOLT score. If you get into this and notice some improvements, please let me know how it goes, so we can compare notes.