The NFL scouting combine begins this week, and there is no more anticipated event at the combine than the 40-yard dash. The 40-yard dash showcases one of the most important traits that can’t be taught in the NFL: speed.

There have been great players in the NFL that weren’t fast—namely Tom Brady, who ran a famously slow 5.18 second 40 in 2000. Still, speed can be a massive advantage for many players, particularly wide receivers, running backs, and defensive backs, the three positions responsible for the fastest times in combine history.

With that, here are the fastest 40-yard dash runs in NFL combine history:

The NFL combine 40-yard dash record was set just last year by Texas Longhorns receiver Xavier Worthy. Worthy ran a 4.25 second 40-yard dash on his first attempt, before breaking the record by running the 40 in 4.21 seconds on his second attempt.

“It’s crazy,” Worthy said after the run. “I watched the combine my whole life as a kid. Seeing John Ross run that, I never thought I’d be able to be on this stage and do that.”

Speed does not automatically translate to NFL success. Though fast 40 times likely helped Worthy and Ross rise in the draft, several of the fastest runners of the 40-yard dash did not go on to have transient careers. Here’s a look at how each of these runners’ careers fared.

Among the 13 runners listed above, only Deion Sanders has made the Hall of Fame. Champ Bailey, who finished just outside this list by running a 4.28 40-yard dash, is also a Hall of Famer.

After Sanders, Chris Johnson is the most recognizable name on the list, and was even tied for the 40-yard dash record for nearly a decade. Johnson was the NFL Offensive Player of the Year, an All-Pro, three-time Pro Bowler, and is one of nine running backs to rush for 2,000 yards in a season.

Jerome Mathis had one extremely successful All-Pro season as a rookie, but only lasted four seasons in the NFL. Stanford Routt, a member of Mathis’s draft class, spent eight seasons in the NFL. Similarly, Marquise Goodwin spent a decade in the NFL as a deep threat option. Rondel Menendez and Dri Archer only lasted a few seasons each in the NFL.

Henry Ruggs is currently serving a 3-10 year sentence after killing a 23-year-old woman and her dog while driving under the influence.

Xavier Worthy, Kalon Barnes, Tariq Woolen, and D.J. Turner are still young and in the early stages of their careers. Woolen already went to a Pro Bowl and Worthy is coming off of a Super Bowl appearance, but Barnes and Turner have spent significant time on the practice squad to begin their careers.

Many of the fastest and most successful players in recent memory ran between a 4.30-4.40 40-yard dash. For example, Julio Jones ran a 4.39 40-yard dash in 2011, Darrelle Revis clocked in at 4.38 seconds Ja’Marr Chase ran an unofficial 4.38 40-yard dash at LSU’s Pro Day, Terry McLaurin ran the dash in 4.35 seconds, Lamar Jackson ran a 4.34 40-yard dash in 2017, and Jahymr Gibbs ran a 4.36 40-yard dash.

The 40-yard dash at the combine has measured several of the fastest players to ever enter the NFL, but by no means has it included all of the fastest players. For one, the NFL combine first took place in 1982. Even when the combine was instituted, runs were hand-timed, leading to more discrepancies than modern, electronically timed sprints.

Since the combine did not start until the 1980s, speedsters including gold medal sprinter Bob Hayes and former NCAA 100 meter record-holder Cliff Branch never ran the 40 at the combine. Hayes was one of the first men to run 100 meters in under 10 seconds. Branch was so fast he claimed at 69 years old he could run a 4.6 40-yard dash time.

Another ageless wonder was former Washington cornerback Darrell Green, who ran a 4.24 40-yard dash at the age of 40. Rumor had it that Green ran a 4.09 40-yard dash in training camp in 1986. Also in the 1980s, Bo Jackson claimed he ran a 4.13 40-yard dash at a regional combine in 1986.