[naiad]

Originally Posted by jome

Towards the end of a maximum static I get what I call "hypoxic contractions" (for the lack of a better term), which compared to the co2 ones are much uglier and ultimately determine the break point. The CO2 contractions you can learn to ignore and tolerate pretty well...

I have also noticed that hypercapnia and hypoxia are quite different feelings. These are from some of my earlier posts...

Originally Posted by naiad

For me, the feeling of CO2 and low O2 simultaneously is less bad than either on its own. A good static is when I get the balance right. A max static is very difficult, but still not as much as the terrible contractions caused by high CO2 alone, or the fierce urge to breathe caused by low O2 without high CO2.

Maybe I'm lucky and the two feelings cancel each other out.

Originally Posted by naiad

I think that both elevated CO2 concentration and extremely low O2 concentration can cause the urge to breathe. I have experienced both separately, although in normal circumstances there would be a bit of both and CO2 would be the dominant one.

High CO2 causes an intense urge to breathe, much stronger than that caused by low O2, but it is more bearable. This is what happens at the end of a CO2 table, or after doing dynamics with short intervals.

Extremely low O2 causes a less intense feeling, but more urgent and unbearable. It usually comes on suddenly and gets rapidly worse, unlike low CO2. This is what happens if I hyperventilate too much before doing a max static. The feeling doesn't always happen, and it is possible to BO without any 'struggle phase'.

Lucia