There is no such record. In fact, there is no official record for 40 yard dash at any age. The dash is used primarily by American football scouts and is not a santioned event by any major sporting organization. The record for NFL prospects is unclear because of flaws in timing methods used. It was timed manually until 1990 and then switched to a manual start and electronic finish. Justin Gatlin, who ran 9.85 for a gold medal in the 100meters at the 2004 Olympics, has a verified 40-yard dash best of 4.42 s. This was the fastest verified time I was able to find, but several NFL players and prospects have clocked faster times using less accurate timing methods that cannot be considered legitimate. Washington Redskins hall of fame cornerback, Darrell Green, once ran the 40 in 4.09 seconds. However, the timing was done manually with a stop watch, so it could easily be off by a half second or more. Green's fastest verified 100m run was 10.08 seconds, so it is unlikely that he could really run the 40 faster than Gatlin.
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