How do American football players like Chris Johnson, Dri Archer and Jacoby Ford run so fast?

The thing that Chris Johnson, Dri Archer and Jacoby Ford all have in common is that they were elite prep track stars from Florida who specialized in the 100 and 200 meter sprints. 

• Chris Johnson ran a 10.3 in the 100m while at Olympia High School in Orlando, FL. At the 2004 state championship, he was runner up in the 100 and 200 behind future 2-time Olympic bronze medalist Walter Dix. He anchored the 400m relay team, which won the state title. 
• Dri Archer went to Venice High School in Venice, FL, where he was teammates with future NFL player Trey Burton. Archer was a track standout with a 10.4 in the 100m. He finished second in the 2008 state championships behind future sub-10 second All American sprinter Dentarius Locke.

• Jacoby Ford was the 2005 100m state champion at Newman High School in West Palm Beach, FL, with a personal best of 10.3. Unlike Chris Johnson and Dri Archer, Jacoby Ford also ran track at Clemson University while playing football. As a five time All American, he was arguably a better track athlete than football player. Though an adequate 100/200 runner, his specialty was the 60m run, an indoor event. He was the 2009 NCAA 60m champion with a time of 6.52; his time was just one hundredth of a second shy of the NCAA championship record held by 3-time Olympic silver medalist Richard Thompson of Trinidad and Tobago (and formerly LSU). 
• The track connection is important to note because these guys have superb sprint technique, which makes them efficient runners on the track and on the football field. Natural speed and power only goes so far. In order to cross into the level of sub-4.4 second times in the 40 (much like sub 10.5 second 100m times), an athlete needs to have great running form and quickness.
  
  In the particular cases of the Chris Johnson, Dri Archer and Jacoby Ford, they each had something else going in their favor
• The main thing to notice about Chris Johnson’s 4.24s 40 time – tied as the fastest 40-yard dash ever recorded – is his 10-y split (how fast he ran for the first ten yards). His 10-y split is a mind-boggling 1.40. This is the fastest 10-y split I have ever seen among NFL players: it’s definitely the fastest among all football players who have run 4.30s and under in the 40. The only player who has come close was Dominique Rodgers Cromartie, who has a 1.41 10-y split (and a 4.29s 40 time).
  
  The 10y-split is significant because it gives a good indication of an athlete's initial burst of speed. Chris Johnson’s split time suggests that he has a blistering fast reaction time and he very fast first steps. As a running back, this means that he can hit the hole so fast that defenses will have a very difficult time spotting him. 
• In Ford’s case, what helped with his great 40 time was that he already specialized in running the 60m race. Unlike the 100m sprint, where one can run a fast time despite a slow start or late top-end speed, success in the 60 requires a fast start and very rapid acceleration, just like the 40. It's worth mentioning that his 3-cone drill (4.44) and 20-yd shuttle (7.00) times were unimpressive, suggesting that he is much more of a straight-ahead runner rather than an agile ball-carrier who can change directions with ease. This is consistent with how he was used by the Raiders, as most of his damage was as a return man rather than as a receiver.

• Summary

  
  That these three athletes happen to be from Florida is admittedly somewhat irrelevant. Speed can come from anywhere. However, their track backgrounds are quite relevant. Each one of these athletes has explosive speed and great technique, along with their own special skills sets. These are the reasons why they ran fast 40 times. 
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