With the Indianapolis Colts set to begin practicing today to begin training camp, they have announced a few injury-related moves that were fully expected. The team announced that outside linebacker Robert Mathis and offensive lineman Donald Thomas have all been placed on the physically unable to perform (PUP) list.
Basically, the PUP is a designation for players who are unable to begin practicing with the team at the start of camp because of football-related activities. They don't practice with the team until they are cleared by the team doctors, but once that clearance comes they are eligible to return to practice immediately.