Falcons running back Warrick Dunn underwent surgery for a herniated disc last week and is expected to miss six weeks, which would encompass all of training camp, ESPN's Ed Werder reported Wednesday. It's the second surgery the 32-year-old has had since the Falcons completed a 7-9 season. In January, he had arthroscopic surgery for a damaged shoulder that bothered him much of the season. At the time, the team said that Dunn would need several months of rehabilitation before he's able to resume football workouts but was expected to make a full recovery.