The 40-yard dash, a standard acceleration evaluation for American football players, does not fall within the usual criteria of athletics racing events. In most 40-yard dashes, reaction times are not recorded as timing starts only once the player is in motion, and the standards for timing a "football 40" are so lax and inconsistent that a real world record cannot be claimed. Performances are also hand-timed and calculated to 1/100th of a second, although studies have shown human beings simply cannot react consistently or accurately enough for this to be a valid method, and even those using light beams are timed by the motion of the athlete, removing the normal factor of reaction time; further, football 40-yard dashes are usually run on a turf surface as opposed to an all weather track. All of these factors make track and "football 40" performances essentially impossible to compare. The world best time for a "football 40" is 4.17 by Deion Sanders, while the extrapolated best for an Olympic-level athlete (including reacting to a starting gun) is 4.24 by Maurice Greene at the 2001 World Championships in Athletics. Under conventional football timing on a turf field in 2017, Christian Coleman reportedly ran a 4.12. Outdoor events Men Women Indoor events Men Women Running records by race distance Notes Javelin specifications The men's javelin specification was changed with effect from 1986, and the women's from 2000. The purpose was to reduce the number of illegal flat landings, but a side-effect was to reduce the distance travelled. The prior world records in individual men's and women's javelin were invalidated, but the prior records in decathlon and heptathlon were not. The old specification records for men's and women's javelin were as follows: The current decathlon world record was set with the current javelin specification. The best performance in heptathlon using the new specification javelin is: Other Notes See also List of Olympic records in athletics Ultramarathon records References External links Records overview – IAAF World Record progression in athletics – athletix.org Track and Field all-time performances Masters Track & Field World Records World Athletics