Of the 2,600 players that are in the NFL, roughly 400 of them are injured every year. That number includes rookies and veterans from each team and counts both minor and extreme injuries.
The number of injured NFL players increased in 2010 from previous years. The number of players that were put on the injured reserve list in 2010 was 464. For comparison, that number was only at 388 in 2009. The injured reserve list is an official designation used by the National Football League for athletes who become injured and temporarily unable to play. The increase in injuries over the years was most likely related to the increase in players' physical fitness and strength as well as to certain NFL rule changes, according to famous Vikings running back Adrian Peterson, cited by NFL.com.