In these steamy days of late summer, when large men in pads batter each other on the playing field, some try to speed their recovery on the sidelines by breathing pure oxygen.
Eagles tight end Josh Perkins did it during this year's final preseason game against the New York Jets, for example, when the temperature at 7 p.m. kickoff was a toasty 86 degrees.
Some physicians have ridiculed the use of 100 percent oxygen, noting that athletes recover perfectly well by breathing regular air, which is 21 percent oxygen. Few researchers have formally compared the two.