Right now, three of the top 20 running backs in career receptions are active: Matt Forte, Darren Sproles, and Reggie Bush. Note that for these purposes, players like Bobby Mitchell, Charley Taylor, and Eric Metcalf — who all entered the league as running backs but then converted to wide receiver — were excluded.

Sproles just turned 33, and entered the league back in 2005. He was a rookie at 22, but as a late 4th round pick, he had just 42 career receptions before turning 26.

Bush was the second overall pick in ’06, of course, and he entered the NFL at just 21. He got off to a blazing start, tying the NFL record for receptions through two seasons set by Larry Fitzgerald. But Bush has not maintain that level of play, and the future isn’t all that bright. He turned 31 in March, and just signed with the Bills, his 5th NFL team. Bush had just 4 catches in five games last year, before an ACL injury in St. Louis ended his season.

Forte, despite being only nine months younger than Bush, he entered the NFL two years later. Forte has been a mix of Bush and Sproles when it comes to the age curve: he started off strong, like Bush, but has aged well, like Sproles. Forte had 223 receptions in his first four seasons in 60 games; In his last 4 years, he has also played in 60 games, and caught 264 passes.

Despite being the youngest of the three, Forte has the most career receptions. Bush had more receptions last year, but given the age difference, Forte seems like the better bet to become the 5th running back — and only 3rd non-fullback — to hit the 600-reception mark.