When it comes to sports documentaries, HBO’s Hard Knocks was revolutionary. It may be impossible to believe it now, but Hard Knocks has been around since 2001 when the Baltimore Ravens first took the plunge to allow HBO cameras into their training camp. Since that time the NFL has had a team highlighted every year as they prepare for the regular season. To help put that in perspective, that’s the year that New Orleans Saints quarterback Drew Brees was drafted by the San Diego Chargers. Now comes news that Hard Knocks will keep going for at least a little while longer. John Ourand of Sports Business Journal reports that HBO and the NFL have agreed to a four year contract extension that will keep the series rolling on. It’s great news for fans of the league and fans of great behind-the-scenes style television. Hard Knocks has been the inspiration for just about every similarly-fashioned behind the scenes documentary about sports. 24/7, All Access, the list goes on and on and on. Without the success of Hard Knocks, none of those programs probably exist today. The show has offered up some classic moments over the years. Who could forget Rex Ryan’s inspirational snack-related speech from a few years ago.