Less than six months after undergoing surgery on a torn ACL in his left knee, former UFC welterweight champion Georges St-Pierre has resumed “gymnastic training.”

Firas Zahabi, head coach at Tristar Gym in Montreal, told ESPN.com that St-Pierre is working out his upper body regularly and expects medical clearance for martial arts training around October. St-Pierre suffered the injury in March.

According to Zahabi, St-Pierre’s recovery is ahead of where it was at this point in his first comeback from a torn ACL -- which occurred in his right knee in 2011 and kept sidelined from martial arts activity for eight months.

“It’s looking way better than the first time,” Zahabi said. “We just finished training and were talking about how his quadriceps got back to size so much faster this time around. No two ACL injuries are the same. We’re learning that.

Georges St-Pierre, left, has been out of action since a close decision win over Johny Hendricks in November. Al Powers for ESPN

“In October, he’s going to try really light martial arts training. Maybe hit pads. A little movement. Nothing crazy. “

Following his ninth consecutive UFC title defense against Johny Hendricks at UFC 167 in November, St-Pierre, 33, announced he was going to take a hiatus from the sport. The Canadian superstar vacated his title as part of the announcement.

Zahabi swears the two do not discuss St-Pierre’s potential UFC return, even during rehabilitation sessions on his left knee. He does, however, admit his personal belief is that St-Pierre will return next year.

“Right now, every time I talk to him, we never talk about his comeback,” Zahabi said. “I’m being 100 percent honest with you. I tell him people ask me about it every day. I think we both just know that there is no answer until he gets back in the gym, in his routine and sees if he wants to continue.

“My personal opinion is he still has plenty of competitive juice in him. I don’t think he’ll be anywhere near fight shape until he’s late-34 -- mid-34. I think he’s got a few fights in him but I don’t want to speak for the guy. He might retire and no one could blame him.”

In an interview with BloodyElbow.com in August, St-Pierre insisted he would not even consider a UFC return unless both he and his opponent were advanced blood tested by an independent anti-doping organization.

UFC vice president of regulatory affairs Marc Ratner has since told ESPN.com the promotion is currently accepting proposals from independent sample collectors and hopes to introduce a year-round drug-testing program by the end of the year.

Zahabi, who has spoken to Ratner about the potential program, said St-Pierre was “happy” about the news. No specific details about the program have been formalized yet, but, in St-Pierre’s case, it would have to be implemented prior to his return.

“From now on, he’s in a place where he doesn’t have to fight a guy if that guy doesn’t do the test,” Zahabi said. “He is a big believer in everybody should be natural.

“Georges is happy. He’s a natural athlete.”