Safety Tanard Jackson, left, with cornerback Morgan Trent, will practice fully Thursday (John McDonnell/THE WASHINGTON POST)

Davis had been sidelined by an injury to his left knee. Signed to Washington’s practice squad last October, he is trying to earn a spot behind backs Evan Royster, Roy Helu and Tim Hightower.

He can’t practice because of a rule in the league’s collective bargaining agreement that prohibits on-field activities for the first day of camp and requires two more days of non-contact drills.

Jackson was activated from the PUP list Sunday and will be allowed to practice fully today. He went through Thursday morning’s walk-through, and has been eager to compete for the starting free safety duties.

Fullback Darrel Young (strained hamstring) was moving around much better than he was two days ago. Young said he feels better as well. He tested out his hamstring with a little running and walking on the treadmill, but he and the team are being cautious not to rush him back before he has fully healed.

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