Mouth open 99% of the time. Other 1% is for making it look effortless when running past either pedestrians or motorists.

Closed, same with sleeping, I think it is a by-product from competitive swimming, or maybe I'm just weird.

You're absolutely weird.

I inhale through my mouth and nose.

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@floathammerholdon | @partners_in_tri

If you can get all the air you need only breathing through your nose, you aren't running hard enough.

This

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https://www.strava.com/...tes/zachary_mckinney

I'm a mouth-breathing neanderthal.

I used to be a mouth breather, but now less so. Coach had me doing specific breathing focused runs (5 step breathing, 5 steps in through nose, 5 out through the mouth), on a 10km weekly lunch run.

As well as the photo vanity benefits, then there's a noticeable aero benefit that's of the same order of ceramic bearings and tapeless bars on the bike. The specifics will depend a bit on the shape of your face of course.

zone 1 or easy zone 2 runs mouth closed. Speed it up or hills, then breathe both mouth and nose.


...

Closed when it's not allergy season, because that means I can breathe through my nose.

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Level II USAT Coach | Level 3 USAC Coach | NASM-CPT
Team Zoot | Tailwind Trailblazer
I can tell you why you're sick, I just can't write you an Rx

Close mouth, open up your stride, run past camera person. If you're feeling extra saucy, give them a little wink. Once you're past, slow down and pant like a dog.

To much drag with mouth open, it acts like a big parachute

Dimples create a boundary layer

Exactly! My Strava profile photo is from a half iron in 2018 where when I ran by the wife I gave the right bicep a hard flex and pointed to it with my left hand. It was a good one too because my wetsuit was too small and I had to fight the full swim so the bicep was especially swollen. The unknown fact is that I struggled to get the arm out of the flexed position for about 10 seconds and had to rub it a few times to prevent it from cramping.

Neither, we should strive to run with a smile :-)

when I started running, training for a ultradistance relay team in HS, our coaches brought in a yogi and ultramarathoner. He advised us to breathe through the nose during morning runs as this would enhance the flow of prāṇa..

these days I just pant like a dog..

I tend to run a little side on also, depending on where the wind is coming from to get the full sail effect-just like a rear disc.

Got a response to this very question already written up! Here you go:

The primary purpose of breathing is to transport air into and out of the lungs. This transports carbon dioxide out and oxygen in. Maximizing that exchange is accomplished by maximizing how much air goes in and comes out of the lungs. If you over-breathe, your body will just stop you from doing that by slowing your breathing rate naturally. If you feel like you need to breathe more, you'll benefit from breathing more and your body will do that naturally.

This all happens, both at rest, and during exercise, because chemoreceptors monitor the level of oxygen in your blood and fine tune your breathing rate to match your needs. These chemoreceptors act just like a thermostat in your house but instead of regulating temperature, they regulate oxygen and CO2 concentrations in your blood.

If you pre-select a breathing rate you're mentally overriding your chemoreceptors which are highly adept at fine-tuning air exchange to match your muscles exact needs. Your exercise performance will be worse because of it.

The best arguments for breathing rhythm focus during exercise are:

1. Intentionally restricting pace of exercise to what can be accomplished with restricted breathing as a way to limit overall exertion level. You still should not intentionally alter your breathing rate, but just pay attention to it, and if you notice it shifts to a faster rhythm than allowed for in your training programming, slow your pace very subtly until your breathing rate naturally falls back down to the prescribed rate without intentional breathing modification.
2. Mindfulness, which is an essential skill for both pace-monitoring, and for assessing how much more you have left to give.
3. Orthopedic rhythm. That is, it's often more comfortable for a person to have an inhale or an exhale to fall in rhythm with their stride.

Common misconceptions:

• "If I'm breathing fast, I'm doing something wrong." No, you're probably just pushing yourself, and if fitness is the goal, that's great. If you always burn out quickly in your training sessions, then sure, go ahead and slow down for at least half your running sessions. But sometimes you should be breathing fast and heavy.
• "In through your nose, out through your mouth." No, your nostrils are tiny air passageways compared to your mouth. The goal of breathing is to inhale and exhale air. Doing so through your nose causes unnecessary resistance to inhalation and will hurt exercise performance, without a doubt. It can be a great calming practice when not exercising, but has no place in running.

My recommendations for breathing during running:

1. Breathe however you like, through both your nose and mouth.
2. Be mindful of your breathing rate if you like, but don't change it artificially.
3. Settle into a breathing rhythm that feels good with your strides.

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Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

If you drill holes at the back of your head, the air passes thru like the vents of a Specialized Evade Helmet LOL!

Also need slits behind ears to help direct airflow thru rear holes.

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Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Already banned by UCI - see the latest Technical Bulletin.

fine for tri and WTC races, though.

Oh great, all of Tony Martin's innovations get banned by UCI...supertuck top tube riding, and now the aeroness of downhill riding with mouth wide open. What's next? Banning biking inside 2m distancing unless masked in an mass start event?

I haven't figured out how to chit-chat with a closed mouth when out for a social jog, so open most of the time.

If others can't keep a decent conversation, I prefer that they rather shut it, as I really don't care for moaning and grunting.

.

That's what the Eustachian tubes and typmanostomy tubes are for. All the more reason to keep your mouth open.

No need to drill new holes. You already have a rear hole in your body that also can provide extra propulsion when optimised!