Here's a pretty interesting article from a few years back. When I was just starting to get into freediving and looking for information, this is the article I found in Outside.
Cheers,
Erik Y.
http://www.outsidemag.com/magazine/1098/9810manfish.html
Cheers,
Erik Y.
http://www.outsidemag.com/magazine/1098/9810manfish.html