Eli5 Why do they say take 3 or 4 deep breaths before a deep dive?
In: Biology
When you exhale, you don’t actually get _all_ of the air out of your lungs. There is still some ‘stale air’ in there that hasn’t been circulated (known as the residual volume – give or take about 1/2-1/3 of the total lung volume). By taking a few deep breaths in rapid succession, you cycle out as much of that stale air as possible, giving you as much fresh air in the lungs as possible.
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