FRISCO, Texas -- Travis Frederick is not ruling out a return later in the Dallas Cowboys’ season, but the four-time Pro Bowl center acknowledged he still has a long way to go before he will be ready to play.

Frederick was placed on injured reserve last week as he continues to battle the effects of Guillain-Barre Syndrome, an autoimmune disease that affects the nervous system. Frederick was diagnosed with the disease late in training camp, but the Cowboys opted to keep him on the active roster for the first four games.

The earliest he can return to game action is Dec. 9 against the Philadelphia Eagles.

Going on injured reserve “has nothing to do with where I’m going and how I’m getting better,” Frederick told ESPN.com. “It’s more about what I’ve missed so far. Basically, what it comes down to is the longer you spend not doing anything -- and now I’m doing some stuff, but I’m not running and doing any football movements -- the harder it is to get back and the longer it takes to get back. So we’re approaching the point where it was going to be another 4, 6, 7, 8 weeks of that sort of stuff on top of the recovery.”

Frederick said he is working out four days a week, splitting time between weights and cardio. He said he was working too hard for what his body could handle at the time and backed off in the last two weeks.

“I’m working about as hard as I can for what I’m doing, but basically at this point it’s about trying to provide a stimulus and an environment for your body to be able to continue to grow and also negating the negatives,” he said. “Trying to keep what muscles that are working at the top of their shape so that as we’re getting more and more [improvement], we can just work on those smaller parts.”

Frederick said he still is dealing with numbness in his arms and legs. He said he has lost strength and some weight, but “the muscles are still there and they’re still flexing, still doing everything. There’s just not as much juice to them.”

Frederick said the regeneration of his nerve is tested twice a month.

“It’s not something where it can say, ‘OK, you’re 50 percent better or you're 80 percent,’ but it is telling me that we’re moving in the right direction and we’re not going backwards, which is definitely a great thing,” he said.

Frederick repeated what he said at the start of the season: He has no thoughts of retirement.

“It’s about being able to get back to it,” Frederick said. “There’s been so few documented cases of people in my situation going from, I’m going to call it Point B to Point C, where you’re a functioning human and trying to get back to an elite athlete level, versus Point A, where you’re suffering from paralysis and other things trying to get back to functioning. ... The focus is getting back to being able to do the things I need to do to come out and play good football.”