Usually runningbacks are the third fastest guys on a football team, they can't run with most WR or cornerbacks, here are 10 exceptions at the NFL level.
No order....
Bo Jackson....10.39 but faster than that
Herschel Walker....placed in the NCAA 100m
Ollie Matson.....Olympic 400 medalist
Curtis Dickey....world ranked sprinter
Michael Bennett 10.18
Travis Williams 9.3 yards a great kick returner
Jonathan Taylor 10.33
Chris Johnson 10.3ish
Adrian Peterson 10,2ish
Rayeem Mostert 10,2ish
Most great sprinters don;t have the size we see in runningbacks.
Tyreek Hill a college RB as was Bob Hayes.
Then there was TCU's Cyrus Leland a white cat back in the 30;s a runningback on the Horned Frogs football team and a 100 yard world record holder at 9.4.
Cy Leland stands out as one of the most successful multi-sport athletes in TCU history, as he ranks as one of the school’s best both on the football field and on the track. An All-Southwest Conference halfback on the Frogs’ 1929 unbeaten conference championship team, Leland rushed for 100 yards four times in his career and three times in 1929. His 13 rushing touchdowns that season stood as a school record for 26 years, while his 17 career scores sat at the top of the TCU career charts until 1956. He led the nation in 1929 with a 7.2 yards per attempt rushing average, and his 93-yard punt return for a touchdown against Baylor that season remains the school record. Despite his football exploits, Leland’s crowning athletic achievement came on the track, as he tied the world record in the 100-yard dash with a mark of 9.4 seconds at the 1930 Kansas Relays.