There have been several threads with people describing rapid heart rate and arrythmia after freediving.
http://forums.deeperblue.net/safety/...rt-issues.html
http://forums.deeperblue.net/general...art-rates.html
http://forums.deeperblue.net/general...ax-static.html
I avoid any training which raises my CO2 level very high, as this causes a great increase in heart rate and I am worried about the risks. For me, hypoxia does not seem to have the same effect, but everyone is different. I do not think it is a good idea to do any training which causes unusual heart rates, even dry.
