A Swiss freediver held his breath underwater for 19 minutes and 21 seconds, according to news reports this week. The gasp-inducing feat beat the previous world record by 19 seconds, and blew away the record of 17 minutes and four seconds that magician David Blaine set on Oprah Winfrey’s talk show in 2008.

For most ordinary humans, all that breath-holding can be hard to fathom. The feat might also bring up some basic questions about biology. For example: Is it really possible to survive without inhaling for that long? And is it healthy?

“It is, as a matter of fact, possible — with certain tricks,” explained Claes Lundgren, a physiologist at the University of Buffalo School of Medicine in New York.

It is probably not, however, good for you, and consequences can be deadly.