[vjanda]

Hi all,
I've been spear fishing for 3 months in Croatia this summer.

I was reading a local magazine in which they discussed some courses aimed at free divers and spear fisherman who want to increase the amount of time they can stay under water.

They made claims of people going from 1min30sec to 4min after the 5 day course. One of the exercises mentioned was the "negative diaphragm exercise"

I tried to find some information on the net about this and similar exercises but failed.

Anyone got some links?

Thanks