**Fun fact:** You do need to take occasional deep breaths (often called alveolar breaths) as they re-inflate tiny sacs in your lungs (alveoli) that absorb oxygen into your blood and can stick together over time due to surface tension.
This re-increases the surface area of your lungs to full, resulting in more oxygen transferring per breath.
It’s why originally people didn’t live for long in “iron lungs” as they neglected to realise how important “sighing” was in this/the necessary re-inflation of alveoli, and regular shallow breathing was unhealthy over time.
It’s also a neat energy hack… if you’re ever feeling sluggish, take a breath, pause then take another one (before breathing out) and this will re-inflate your lungs fully and should give you a small energy boost.
I see a lot of people here missing one of the big points: We breathe primarily to get rid of carbon dioxide, not to get more oxygen. In fact, if we didn’t make any carbon dioxide as a waste product at all, we would only have to take a single breath every 3 minutes to function fine. This is because our bodies make carbon dioxide much faster than we lose oxygen.
Taking a shallow breath means we get rid of carbon dioxide more quickly, because more exchanges happen via diffusion in the lungs. And because carbon dioxide buildup happens quicker than oxygen depletion, shallow breaths are an efficient way of pumping carbon out.
But, deeper breaths take *in* more oxygen. We don’t do this simply because your body doesn’t need that much oxygen in a normal setting, such as when you are lying in bed. So there is no point taking a deeper breath. Taking a deeper breath is useful however, when you are doing something energy intensive (e.g. running!) which is when you’ll start panting.
It’s efficiency vs peak
A lot of processes and systems within the body are designed to move at the most efficient speed possible, a more balanced longevity kind of way. Then almost all of them have the ability to kick into high gear
It’s just a function of how we evolved, in times of scarcity you don’t want to waste energy, but if you’re being hunted or hunting then you need to stay competitive
A similar analogy is to movement of our bodies. We can crawl, roll, wiggle, walk, run, jump, sprint whoever we want to move somewhere else. However we walk because it takes the least amount of energy to do. We call have different speeds for that walking but it’s roughly the same among different people.
The same thing is true with breathing. The lung has a certain amount of compliance, or ease of expansion. Also the small the lungs become, the more force it takes to open up because you are fighting the hydrostatic forces of water within the lung. The bigger they get, now there is recoil affect from the lungs that pulls them back in. Basically there is a sweet spot there that allows us to breath without fighting as much recoil and hydrostatic pressures. That zone allows us to breath without increased amount of work and we call this zone of breathing the resting tidal volume. That extra breath above normal breathing is call the inspiration reserve capacity. The amount we can breath out from baseline is the expiratory reserve capacity. And the total amount of all three together is called the forced vital capacity. However we don’t need to use the forced vital capacity for most people because we have more lung tissue than we need (for most people) and makes it so we don’t need that extra air to come in to make up for it. Basically it uses lots of energy to use all of that lung like that and is why people that have bad lung disease tend to become so skinny (burning too much energy to breath).
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