Artur Beterbiev turned 38 on Saturday, which makes him one of boxing’s oldest reigning world champions.

You wouldn’t know it, according to his assistant trainer. In fact, John Scully has never seen the type of improvement from a boxer Beterbiev’s age that the unbeaten IBF/WBC/WBO light heavyweight champion has made in recent years.

Scully discussed Beterbiev’s unusual career arc during an open workout Wednesday to promote the pulverizing puncher’s 12-round, 175-pound title fight against Anthony Yarde on Saturday night at OVO Arena Wembley in London.

“Honestly, and I mean it – I’m not just saying it,” Scully told Queensberry Promotions’ commentating crew. “And I’ve said this. You could see online, I’ve said this. I think he’s the only guy I’ve ever seen who’s gotten better in his mid-30s. I think his fights with Marcus Browne and Joe Smith, he did things and he performed in a way better than when he was 30.”

Beterbiev blasted through Long Island’s Smith (28-4, 22 KOs), then the WBO champion, in his most recent fight. He sent Smith to the canvas once in the first round and twice during the second round, when their scheduled 12-round championship unification fight was stopped June 18 at Madison Square Garden’s Hulu Theater in New York.

Hartford’s Scully, who went 38-11 (21 KOs) mostly as a light heavyweight, attributes Beterbiev’s ability to improve at this late age to his habits in and out of the ring.

“I think his devotion to his religion,” Scully said, “he doesn’t drink, he doesn’t smoke, he doesn’t hang out, and I just think it’s kept him preserved. You know, his whole mentality, he’s like a 28, 29-year-old guy, not 38.”

The Russian-born, Quebec-based Beterbiev (18-0, 18 KOs) didn’t make his pro debut until he was 28, nearly 10 months after he lost to Oleksandr Usyk at the 2012 Summer Olympics in London. He has had only 18 professional fights in almost 10 years in part due to promotional issues and injuries, but Scully believes Beterbiev has succeeded in spite of his inactivity because he is completely committed to staying in shape.

“He alleviates that because he trains,” said Scully, who assists Beterbiev’s head trainer, Marc Ramsey. “He’s always in shape. You’ll never see him not be able to do things physically. He’s always in good shape. His mentality is always within range of being ready for a fight. So, I don’t see it as a problem.”

Most sportsbooks list Beterbiev as at least a 9-1 favorite over England’s Yarde (23-2, 22 KOs), who is the mandatory challenger for Beterbiev’s WBO belt. Beterbiev-Yarde will headline a BT Sport 1 broadcast in the United Kingdom and Ireland (7 p.m. GMT) and an ESPN+ stream in the United States (3:30 p.m. ET; 12:30 p.m. PT).

Keith Idec is a senior writer/columnist for He can be reached on Twitter @Idecboxing.