Trent Richardson practiced on Thursday after missing the beginning of camp. (USATSI)

After starting training camp on the "Active/Non-Football Illness" list, Trent Richardson hit the practice field with the Oakland Raiders on Thursday for the first time since camp began. Richardson also denied that he missed the beginning of training camp because he was overweight.

Instead, he says he was down sick with pneumonia.

"I had pneumonia," Richardson said via the San Jose Mercury News. "It was in the back of my lungs, so that's nothing to play with."

On Sunday, head coach Jack Del Rio said the following about Richardson's absence from practice:

"Trent is here, he came back very close to the weight, which was a pretty ambitious goal to get to and he's down in the low 220s. That's what we asked of him, that's where he was as a player at 'Bama. I believe that, with Trent committing himself like that and getting in that type of shape, that he'll have a chance to come out here and show what he’s really capable of."

But on Thursday, Richardson denied that he was anywhere close to being overweight.

"I was nowhere near overweight," Richardson said. "I actually came back in around 222. I was actually below what coach wanted me to come in at."

Regardless of the reason for his absence, Richardson has his work cut out for him. Since he has been gone, undrafted rookie Michael Dyer has been a practice star and could threaten his roster spot. With Latavius Murray already in control of the No. 1 spot on the running back depth chart, with Roy Helu expected to play some sort of role, and now with Dyer's emergence, there's not much room left on the ship.

Still, Richardson seemed optimistic after his first practice with the team. 

"It feels good," Richardson said via Fox Sports. "It's probably been the most eager I've been to go to practice for a long time. It's been a long time coming for me."