After languishing on the sidelines for over half a year, Anthony Pettis is finally back in gym. The UFC's exciting but injury prone lightweight champion, who pulled out of a December 2013 title defense against Josh Thomson due to a torn posterior cruciate ligament (PCL) in his left knee, was cleared to return to full contact training at Milwaukee's Roufusport academy last week.

"I feel good," Pettis told MMAFighting.com. "I had my first kicking session on [Wednesday]. The doctor said (it would be) six months from surgery to impact. I did that, I didn't kick at all for six months.

"We had a sparring session and I felt good. Definitely, I wouldn't say it was 100 percent. I still feel like I'm second guessing the knee, but it's still fresh off. I think with two months of kicking, I'll be back normal."

It's been 10 months since Pettis last competed, when the 27-year-old wrested the UFC title away from his old WEC rival, Benson Henderson, with a slick and surprising first-round armbar at UFC 164.

Yet because of the delayed timetable caused by his filming of The Ultimate Fighter 20, which began on Monday, nearly 16 months will have passed before Pettis returns to the cage this winter, most likely on December 6 at UFC 181. The process has been long and largely agonizing, he admits, although Pettis has also been able to glean a few positives from it as well.

"Having [the time off] is hard, man," he said. "All you do is train. All you do is get ready for your next fight and have a next opponent in front of you. It felt good though. I needed it.

"I got to heal everything. Every time I was doing a fight, there was something bothering me. As a mixed martial arts athlete, there's so much that goes into it from the conditioning side, the boxing, the kickboxing, the jiu-jitsu. The way I fight, it's very athletic. So it's hard to say what caused the injuries or what's making the injuries happen, but definitely, this next camp, I'm going to do it a little smarter, a little less involved with the sparring and a more involved with technique."

It's true that injuries have become somewhat of a running theme four years into Pettis' UFC career. During his final 12 months in the WEC, from December 2009 to December 2010, Pettis fought five times. It's a figure which now appears relatively remarkable, considering that Pettis has managed to only match that number in the collective four years since.

Though now that Pettis is champion, the narrative of his inactivity has shifted. Before, when Pettis was just another exciting contender in the UFC's loaded lightweight division, a 16-month absence could be worked around. Now, his idleness affects every 155-pound fighter under UFC contract, and more than a few restless contenders have already begun grumbling about Pettis holding up the division.

"I don't think these guys are educated whatsoever," Pettis said in response. "The TUF gig is something I didn't choose to happen. The UFC chose that. I'm not going to say no to an opportunity like that. That signs me up for three months filming for that, so that's why the fight got pushed back all the way. I could be ready to fight by August, at the latest. From now to August, if I started a training camp, I could be ready to go.

"But that's what [the other lightweights] are supposed to do as well. The division needs to somehow keep themselves relevant. The main guy doing it, Ben Henderson, I beat him twice, so he can talk all he wants. He's going to have to wait his turn. There's a couple guys that can talk and I guess they deserve their shot, but at the same time, I was in the same position as them guys. I was talking and I was trying to make my case to get that title shot."

Henderson isn't alone, as lightweight's resident undefeated Dagestani, Khabib Nurmagomedov, recently engaged Pettis in an amusing Twitter back-and-forth, with Nurmagomedov proclaiming "I do not touch the disabled" and asking Pettis "how much of disability payment do you get?"

Though Henderson, in light of his recent electric submission over Rustam Khabilov, has been the most vocal lightweight of late. The former record-tying champ has already fought two top-ranked contenders since his loss to Pettis, and made it clear that he intends to maintain a busy schedule, publicly raising the question of what impact Pettis' inactivity has on the belt and challenging all No. 1 contenders to come see him instead.

Regardless, Pettis isn't impressed.

"I think it's funny," Pettis said. "I beat Ben twice. Like, why is he even saying that? If he wants to consider himself the interim champ, we all know who the real champ is, so he can keep saying that. They're all pleading their case. They all want a title shot. Honestly, Ben is a great fighter. He's a great guy. I mean, I like the guy, it's just, I think I got his number.

"Ben is one of the best lightweights in the world. I'm just better. He won a belt in WEC. I took that away from him. He won the belt in UFC. I took that away from him.

"I beat him twice," Pettis finished. "So it makes it that much harder to hear him say anything."