It’s understandable to feel that way, particularly since a lot of the formal breathing exercises we know in the west come from yoga practices which are thousands of years old and have all sorts of metaphysics tied up in them. But it doesn’t seem too hard to believe that having a nasal cavity to regulate air temperature, block dust, increase moisture, etc would be beneficial to the lungs.

Here is one somewhat extreme experiment on rats that showed continual mouth breathing had negative cognitive effects [1]. There is also research that has correlated nasal cycle dominance to different cognitive functions [2]. I’m not totally sure about the covid-19 links this paper makes, but it’s interesting to note the sinuses help create nitric oxide and NO plays a wide range of biological roles [3].

Personally, I do pranayama every morning before seated meditation as well as right before bed and find it to have great emotional benefits if nothing else.

[1] https://www.jstage.jst.go.jp/article/josnusd/61/1/61_18-0006...

[2] https://pubmed.ncbi.nlm.nih.gov/8063547/

[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7200356/

I was given "only nasal" as an endurance tip as a child and always understood that simply as a helpful intensity limit guide: if you stick to "noseable" level you won't find yourself completely exhausted any time soon.

It may lack sophistication but it's surely helpful for people who haven't yet learned how to spread out their endurance. But whenever something works in the realm of athletic performance, there'll be a flock of people who make up the wildest theories to explain how it works and misapply it to situations where it's actually completely wrong. So I totally get that "woo-wooh"

My kickboxing teacher just said "breathe like this" and nobody had time to ask questions. I've often found it to be pretty beneficial to have proper breath control. Because breathing in through your nose when exercising hard isn't instinctive, you practice breath control very consciously.

I must admit I'm a little curious what kind of woo-woo could surround proper breathing.

> ... the “only breathe through your nose” crowd always seemed a little woo-woo.

Can highly recommend 'Breath' by James Nestor, for some science-focused, non-woo look at the practice.

(I'm about 3/4 the way through it -- so I can't guarantee woo-free content in last quarter, but based on extrapolation we should be fine. :)

Not quite. Investigate the work of John Mew. ( considered a quack by mainstream, I think, though I personally I find him credible)