Middle linebacker Mike Barrow wore full pads and participated in some agility drills on Tuesday, but he sat out the team's two-hour practice to continue resting his left knee. Barrow has tendinitis in the knee and has missed all three of the Redskins' preseason games.

Barrow said his knee has been feeling better, but added that there's no established timetable as to when he'll return to the practice field.

"I've never been hurt this long in my career, so it's frustrating," Barrow said. "We push it every day and if I irritate it, we just back on down. It's a learning experience and right now I'm learning what I can and cannot do."

Said Joe Gibbs: "Mike did some agility drills with the pads on and his work level is moving up some. He's going in the right direction. It's just a matter of how long it's going to take."

Barrow, 34, joined the Redskins from the New York Giants last April. He is in his 12th NFL season and has been durable throughout his career, missing just five games.

In Barrow's absence, Antonio Pierce has been starting at middle linebacker. The Redskins also have veteran Kevin Mitchell and second-year player Clifton Smith.

Barrow said he has been staying sharp by studying play calls and adjustments during practices. But that only goes so far.

"Obviously there are some limitations when you're not out there," he said. "I try to stand behind the unit and try to take steps like I was making calls. But you have to be in the fire to really experience what's going on."

Meantime, linebacker LaVar Arrington sat out practice again. The three-time Pro Bowler has a sprained knee.

Said Gibbs: "LaVar is getting closer. [Trainers] did some agility drills with him today, which is the next step for him. We need to get him to the point where he can really run full-go. Then we'll move him toward putting the pads on. LaVar told me today I'm anxious to get back out there.'"