Back in 2012, another couple of football geeks asked the question of how much usage is too much usage for a running back in a single season? There was an interesting conclusion reached by Aaron Schatz of Football Outsiders
A running back with 370 or more carries during the regular season will usually suffer either a major injury or loss of effectiveness the following year, unless he is named Eric Dickerson.
Schatz did his study back in 2004 which was about the time of the golden era of “bellcow” running backs in the NFL.