Side by Side

HOW DO THE FASTEST MEN ON THE FIELD COMPARE TO THE FASTEST MAN IN THE WORLD?

There are a lot of fast guys in football, but how does their speed compare to Usain Bolt's? It's hard to say. Since 1990 the NFL combine has used hand timing at the start of the 40-yard dash and electronic timing at the finish, but it has never used fully automatic timing, in which both the start and finish are electronically clocked. The fastest official time recorded at the combine 40 is the 4.24 seconds by Titans running back Chris Johnson in 2008. At the 2010 combine, Texans wide receiver Trindon Holliday ran a 4.21, but it was "unofficial" because it was entirely hand-timed.

While at LSU, Holliday ran 10.0 in the 100 meters, the fastest college 100 ever by a future NFL player. He clearly has world-class speed, but his best 60-meter time (6.54) put him in second place at the '08 NCAA indoor championships behind his LSU teammate Richard Thompson (6.51), who took silver in the 100 meters well behind Bolt at the '08 Olympics. The Patriots' Jeff Demps, who reportedly ran 4.26 in the 40 in college and won the NCAA 60 meters in 6.53 in '11, competed for the U.S. in the prelims of the 4 √ó 100 at the London Olympics, but he didn't make the team in the individual 100.

Johnson has repeatedly suggested that he could beat Bolt in a 40, but the numbers aren't in his favor. Johnson was an outstanding 100-meter runner in high school but lost the Florida state championship in '04 to Walter Dix, who was third behind Bolt at the '08 Games. (Bolt is only 11 months younger than Johnson, and both ran the 200 as high schoolers in '04—Johnson in a lightning 21.30 and Bolt in an unprecedented 19.93.)

According to an SI analysis that used data from Bolt's world-record 100 (9.58) and two methods of estimating Bolt's 40 potential, the Jamaican might flirt with four seconds flat. In his '09 record run, Bolt hit 40 meters in 4.64. Given his velocity, the conversion to yards and his reaction time to the starter's gun, Bolt ran a 4.19 40, but that was in a phase of the 100 in which he was not yet at top speed. Plus, the average difference between handheld times—like those at the combine—and an electronic time like Bolt's is 0.22 seconds. Subtract that, and Bolt is under 4.

Then again, there are other factors, such as the softer (therefore slower) surface at the combine and the lack of starting blocks, both of which would add fractions of a second to Bolt's time. "All things considered," says Ralph Mann, USA Track & Field's director of the elite athlete sprint-and-hurdle program and a world-renowned biomechanist, "I would guess he may just be able to break four seconds. It would be close."

Chris Johnson has suggested that he could beat Bolt in a 40, but the numbers aren't in his favor.

PHOTO

SIMON BRUTY (BOLT)

BLOWN AWAY Bolt is the undisputed king at 100 meters, but converting his record 9.58 to 40 yards provides an idea of exactly how fast he is.