Age is just a number. Of course, in football, this greatly depends on the position. For quarterbacks age seems like nothing more than just a number with the likes of Peyton Manning, Brett Favre, Tom Brady and John Elway putting up high productive and winning seasons as starting quarterback late into their 30's - i.e. Elway won back-to-back Super Bowls at age 37 and 38.
On the hand, running backs who are generally the workhorse of the team face contact on nearly every play they are on the field for have a much shorter shelf life. Age is seemingly everything to them.
When it comes to running backs and age related records, the numbers and achievements dwindle very quickly post-30:
The oldest player to every rush for more than 100 yards in a single game - MacArthur Lane rushed for 144 yards at age 38 (1978 - Kansas City Chiefs), he'd finished the season with only 277 total rushing yards.
The oldest player to rush for 1,000 yards or more in a season - John Henry Johnson rushed for a total of 1,048 yards at the age of 35 (1964 - Pittsburgh Steelers).
We decided to take a quick look at the top 50 running back season by 30+ year olds since 1990 (sorted by rushing yards):
As you can see from the above, since 1990, there have been only 27 times in which a running back who was 30+ years old broke the 1,000 yard milestone with only 3 of those rushing seasons breaking the 1,500 rushing yards barrier.
When it comes to fantasy football, the running back position has traditionally been one of the most important as there is a significant tiering among the various backs.
For the 2014 NFL season, here is a list of running backs who are aged 30+: