the strongest running back in the nfl is running back Steve
slaton he was known for excellent speed and tremendous strenght in
his career for Virginia and carries it out through the nfl he will
be a top 5 back in the nfl.
The hardest running backs would definatley be Jacobs,Reggie
Bush,Adrian Peterson, Warrick Dunn and i know he isn't a running
back but Micheal Vick...hes scary good.