Arizona Cardinals general manager Steve Keim has expressed his belief that running back Andre Ellington will have to get "stronger" to endure the rigours of a full NFL season.

The 26-year-old was named as the club's feature back for the 2014 campaign and had a solid start to the year before injuries slowed his production to a meagre 3.3 yards per attempt, while his season finished prematurely due to sports hernia surgery.

"When I went back and looked at some of the cut-ups, you can't deny his skills - his feet, his acceleration - he's got dynamic skills and game-changing speed," Keim told reporters.

"That being said, it remains to be seen whether he can stay healthy for a full season. To me, that's why this off-season is so big for him.

"He's got to get bigger and stronger in the weight room and he's got to prove he can stay healthy through a full 16-game season."

Ellington recorded 660 rushing yards and three touchdowns for the Cardinals in the 2014 season.