Still , USA Today has reported NFL legend Bo Jackson 's time of 4.12 seconds at the 1986 NFL Combine as the fastest official time ever .
In 2008 Johnson registered a blazing 4.24 40 - yard dash time .
USA Today has reported NFL legend Bo Jackson 's time of 4.12 seconds at the 1986 NFL Combine as the fastest official time ever .
In 2008 Johnson registered a blazing 4.24 40 - yard dash time .