By Keith Idec

Joseph Parker sees all the videos and photos of a perfectly sculpted Anthony Joshua training extremely hard.

Parker’s physique isn’t nearly as photogenic, but the unbeaten WBO heavyweight champion thinks his rigorous training regimen is more effective because he has been able to go 12 rounds. Joshua, on the other hand, has tired later in fights, according to Parker.

“My body type, even though it’s not really muscular, [has] worked for us,” Parker told Sky Sports for a story posted to the network’s website Saturday. “We know that we can fight hard from round one to round 12. It’s all that matters.”

New Zealand’s Parker (24-0, 18 KOs) and his trainer, Kevin Barry, hope taking England’s Joshua (20-0, 20 KOs) into the later rounds works to their advantage in their 12-round title unification fight.

“I see videos posted everywhere of him doing the most sophisticated, new-age training methods that man has ever seen and yet, he has looked very tired in his last couple of fights,” Barry said. “Every time he has been asked to go on to the later rounds, he’s really struggled. So that’s a question for his training staff. He wouldn’t want to be slowing against Joe because I can promise you this – Joe will be coming on in the later rounds.”

Each of Parker’s three WBO championship matches have gone all 12 rounds. Only four of Joshua’s 20 professional fights have gone beyond the third round and none have reached the 12th round.

They’ll fight for Joshua’s IBF, IBO and WBA titles and Parker’s WBO belt March 31 at Principality Stadium in Cardiff, Wales (Sky Sports Box Office; Showtime).

“When you watch him, when you see all the training,” Parker said, “it’s like they are doing all this new training and it looks really hard, and it looks intense, and it looks like the type of training that will prepare you for 12 rounds. But in saying that, just maybe their team need to work on a few things. We know that our team has a good structure and a good training program that will allow us to fight for 12 rounds if we need it. But I’m not sure why he tires. That’s something he has to sort of figure out.”

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