In MPH what is the fastest a human has ever run?

Since Usain Bolt became the 100m WR holder with a 9.69 (Beijing - 2008) and now (August 17, 2009 - Berlin) a 9.58, I don't know if this figure still stands but in the 1996 Atlanta Olympics, Donovan Bailey in a WR time of 9.84 secs, covered a 10m portion at 12.1 meters per second. That would translate to about 27 MPH or about 43 Km/h. Both he and Maurice Greene hit a 10m section of the 100m final of the 1997 World Championships at 11.91 m/s... Greene ran a 9.86 and Bailey ran a 9.91. That would mean both reached a speed of roughly 26.5 MPH. Considering that, even the reductions the WR has taken in the last 12 years, it would be okay to assume 27-28 MPH is the fastest speed ever attained by a person running.

Though Bob Hayes, in 1964, ran his leg of the 4x100m relay in 8.50 seconds.

During Usain Bolt's World record 100m sprint (9.58) at the 2009 Athletic Championships in Berlin, Usain covered Bolt reaches his top speed of 12.27 m/s or 27.45 miles per hour at the 65 meter mark.

For a biomechanical breakdown of Bolt's 9.58 WR, see:

http://berlin.iaaf.org/mm/document/development/research/05/31/54/20090817073528_httppostedfile_analysis100mmenfinal_bolt_13666.pdf

First answer by Dlmick. Last edit by CB70. Contributor trust: 4 [recommend contributor]. Question popularity: 9 [recommend question].