I really liked the period when I did freediving, and practiced to hold my breath. Doing "CO2-tables", almost like intervals except holding your breath. (And as in running, you don't run a marathon every workout, so didn't "push" it to the extreme these breathing sessions). A CO2-table for instance could have you hold your breath for 3 minutes, breathe normally for 90 seconds, then again hold for 3 minutes, then only 80 seconds break etc, decreasing the break each time.
It's quite a sensation overcoming the "need" of breathing. To truly learn that the feeling of having to breathe is only because of CO2 buildup in your body, not because of lack of O2. Mind over body.
It's something to be careful of, but doing it for a short time is probably fine.
When sitting around, people exhale 4-5% CO₂. That's 40000 - 50000 ppm. But the Navy has done studies at that level and found it doesn't have a noticeable effect¹.
Thus, CO₂ at 40,000 ppm for 2 weeks did not affect performance on multiple tests of cognitive function in physically fit young airmen, a population probably not unlike submariners.
Comments
I really liked the period when I did freediving, and practiced to hold my breath. Doing "CO2-tables", almost like intervals except holding your breath. (And as in running, you don't run a marathon every workout, so didn't "push" it to the extreme these breathing sessions). A CO2-table for instance could have you hold your breath for 3 minutes, breathe normally for 90 seconds, then again hold for 3 minutes, then only 80 seconds break etc, decreasing the break each time.
It's quite a sensation overcoming the "need" of breathing. To truly learn that the feeling of having to breathe is only because of CO2 buildup in your body, not because of lack of O2. Mind over body.
Indeed there are many ways to experience it: https://news.ycombinator.com/item?id=27159001
CO2 is toxic at high concentrations though.
It's something to be careful of, but doing it for a short time is probably fine.
When sitting around, people exhale 4-5% CO₂. That's 40000 - 50000 ppm. But the Navy has done studies at that level and found it doesn't have a noticeable effect¹.
[1]: https://nap.nationalacademies.org/read/11170/chapter/5#54