40-yard dash

The 40-yard dash is a sprint covering 40 yd. It is primarily run to evaluate the speed of American football players by scouts, particularly for the NFL Draft but also for collegiate recruiting. A player's recorded time can have a heavy impact on his prospects in college or professional football. This was traditionally only true for the "skill" positions such as running back, wide receiver, and defensive back, although now a fast 40-yard dash time is considered important for almost every position. The 40-yard dash is not an official race in track and field athletics and is not an IAAF-recognized event.

The origin of timing football players for 40 yards comes from the average distance of a punt and the time it takes to reach that distance. Punts average around 40 yards in distance from the line of scrimmage, and the hangtime (time of flight) averages approximately 4.5 seconds. Therefore, if a coach knows that a player runs 40 yards in 4.5 seconds, he will be able to leave the line of scrimmage when a punt is kicked, and reach at the point where the ball comes down just as it arrives.

Timing method and track comparisons
In terms of judging a person's speed, the best method of timing is through lasers which start and stop the times when passed through. A laser start (from a stationary position) is more accurate for measuring pure speed as it does not register a runner's reaction time. However, the method of timing a 40-yard dash can affect the accuracy by as much 0.5 seconds (with the manual stopwatch method). The National Football League (NFL) did not begin using partial electronic timing (started by hand, stopped electronically) at the NFL Scouting Combine until 1990.

In track and field races, the runner must react to the starting gun, which takes approximately 0.24 seconds, based on FAT timing. For electronically timed 40-yard dashes, the runner is allowed to start when he wishes, and a timer hand-starts the clock. This aspect means that comparisons with track times are impossible given that a reaction time is not factored in. Furthermore, the use of hand-timing in the 40-yard dash can considerably alter a runner's time; the methods are not comparable to the rigorous electronic timing used in track and field.

Records
This is a list of the official 40-yard dash results of 4.30 seconds or better recorded at the NFL Scouting combine since 1999, the first year electronic timing was implemented at the NFL Scouting Combine. Prior to 1999, 40 yard dash times were somewhat unreliable and often prone to exaggeration.

In 1986, Auburn's Bo Jackson ran the fastest 40 yard dash at an NFL combine, with a reported time of 4.12. This time was scrutinized, but a time of 4.18 run by Jackson within the same week added some support to the legitimacy of the times. Deion Sanders ran a 4.27-second 40-yard dash in 1989.