Tony W said:
As I understand it hyperventilating is when you are breathing too fast to be able to get enough
oxygen into your lungs -- in this case you are unlikely to be able to continue for very long
without blacking out!!
I'm not a medic but I think hyperventilating is when you breathe sufficiently fast to remove CO2
from the body faster than your body is producing it.
Typical resting pCO2 is about 40mmHg. With hyperventilating this can be reduced to about 30mmHg. The
"must breathe" reflex occurs at about 50mmHg.
But, because normal blood is about 97-98% oxygenated, the hyperventilating doesn't
(significantly) increase the O2 available to the body but it can double the time before the "must
breathe" feeling occurs.
Particularly when swimming underwater this can mean that people can hold their breath until they
blackout, often with fatal concequences.
On a bike I suppose the eventual result could also be a blackout (leading to a fall) but I would
expect it might actually be quite hard to hyperventilate normally. At the end of a downhill prior to
going uphill might be possible - I don't know if this would be possible and I'm not going to try!
The only time I have ever hyperventilated (accidentally) was when (trying) to play a flute. There is
no resistance to the blow and, unless you are doing it properly, most of the air doesn't produce
much if any effect on the instrument so you end up blowing very hard for very little effect. It was
when I stopped that I started feeling very light headed - presumably I wasn't breathing enough.
Regards,
Tim.
--
God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t," and there was light.
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