Infantrycak is correct. Once they are designated as such, they are prohibited from practicing with the team. They can, however, rehabilitate and participate in team meetings. If a player begins training camp on the PUP list, they can be moved to the active roster at any time, even after one practice. A player is not allowed to be placed on the PUP list if they start training camp on the active roster. A player who is put on the PUP list before the preseason's first roster cutdown must remain inactive through the sixth week of the regular season. At that point, he has a three-week practice "window" before he must either return to the 53-man roster or end his season on injured reserve.