The impression most people have of Vitali Klitschko is that he works very hard. On Wednesday, during a open workout in Los Angeles, his main sparring partner and trainer confirmed it.

If anyone knows what the Klitschko brothers are like in the ring, it’s Johnathon Banks. The cruiserweight-turned-heavyweight has been Wladimir’s main sparring partner for about four years and is working with Vitali for his fight against Chris Arreola on Sept. 26 at Staples Center in Los Angeles. They have sparred seven, eight sessions since camp opened in L.A., Banks said.

Banks (21-1, 15 knockouts) has come to admire the brothers.

“One thing about (Vitali) and his brother, they train alike. They train hard all the time,” he said. “ÔǪ All you have to do is watch them work out and you’ll know why they’re successful. They train like the underdog every time.

“That’s what I’ve noticed from them. And now I try to add that to my own training.”

Klitschko said Banks is a “very good fighter, good technically. He’s not as big as Chris Arreola but his speed is very good.”

Banks had better be good – and resilient. Klitschko, a giant at a rock-solid 6-foot-7¾, demands a lot from his sparring partners, Banks said.

“They don’t like nothing that’s easy,” he said. “If they have a sparring partner who’s too easy to hit, after the first day, they’ll send him home. A sparring partner who can hit them and won’t get hit at will, that’s the type of guy they believe will take them to the next level.”

Klitschko said he is always training. It’s his “lifestyle,” he said. Even when he was out of boxing for almost four years, recovering from injuries, he said he stayed in shape. He ran, he swam, he surfed, which he still does at Southern California beaches.

So it was no surprise when his long-time trainer, Fritz Sdunek, said he never has to push his prot├®g├® to train.

“It’s very easy to work with Vitali,” Sdunek said through a translator. “The only problem is that he has so many different appointments, so many things going on. Sometimes he runs late. He’s self motivated, though. Sometimes I have to slow him down when he’s training.

“He’s very self critical. If I say I like what he’s doing, he says, ‘No, I want you to tell me what I’m doing wrong.'”

That might be one reason Klitschko is a dominating fighter at 38 years old.

“He’s getting better all the time,” Sdunek said, “because he’s so self motivated. He’s always look for new, different training methods. He’s always evolving. With experience, I see his level of effectiveness increasing.”

More Sdunek: Sdunek isn’t as well known as Emanuel Steward, Wladimir Klitschko’s trainer, in the U.S. However, he is very famous in his native Germany.

Sdunek, who has worked all of Klitschko’s pro fights, has trained 12 world professional champions (including both Wladimir before he switched to Steward), eight Olympic medalists and many European champions.

He learned his trade as a part of the former East German sports machine. He studied sports science at an East German university, not far from his small hometown of Lussow, near the Baltic Sea.

“I think the training methods are effective,” he said. “I still use a lot of the techniques I learned there.”

Sdunek, 62, started as a boxer during a time when no East Germans could fight professionally. He said he had 129 amateur fights, winning 99. He was a champion of East Germany and student champion of all the universities there.

“I was at the top level of boxing there for about four years. Then, in 1972, I started went into training,” he said.

Michael Rosenthal can be reached at [email protected]