VONTAE DAVIS WAKES just after sunrise on a weekday in August and wonders how he'll start the day. He has little on his schedule -- a lunch meeting with his business partner and maybe some household chores -- so he decides to spend his morning doing something familiar, a routine from his NFL playing days: logging an hour in his hyperbaric chamber.
He zips himself inside the pill-shaped device -- an inflatable mattress meets sleeping bag -- and breathes in the pure, compressed oxygen. To pass the time, Davis reads a business book on his Kindle.