NEW YORK:

Michael Phelps is the latest athlete to use a hyperbaric chamber to aid recovery.

The 16-time Olympic medalist said Wednesday he had been sleeping "at 8,000 feet every night" for almost a year. The 26-year-old swimmer says he realised he bounced back from workouts better when he trained at altitude, so he's trying a device that simulates that.

Phelps says "that's something that is so important to me now being older, I don't recover as fast as I used to."

He says the chamber looks like a fish tank around his bed and the only downside is trying to watch TV through its walls.

Phelps is preparing for what he says will be his final Olympics this summer in London.