How Michael B. Jordan got that ripped boxing bod for ‘Creed II’

The typical training montage for a “Rocky” film lasts only a few minutes. The reality of getting actors to look and move like battle-hardened boxers takes more effort.

Coming off his buff bad guy success in “Black Panther,” Michael B. Jordan had to challenge his physique yet again to reprise his 2015 role of Adonis Johnson in “Creed II,” opening this week. Because, you see, he doesn’t maintain that look year-round.

“He doesn’t work out a lot in the off-season,” Corey Calliet, who has been Jordan’s personal trainer for the past four years, said of his client. “It took about four months to get him ready.”

And the way Jordan looked as Killmonger in the Marvel film wasn’t what they were after.

“We needed to start off with thinking, ‘What does this character look like?’” Calliet said. The well-known celebrity trainer, who sports an impressive physique himself, wanted Jordan to have the conditioning of a boxer. It’s not just about being pretty from the neck down.

For “Black Panther,” the goal was to be massive, and his client lifted many heavy weights to add mass. But for “Creed,” a different tack was taken.

“We needed to do a lot of high-intensity training,” Calliet said. He explained that there was little that resembled old-school bodybuilding techniques: lift heavy, take a break, lift heavy again. Rather, it was a massive mixture of muscle-morphing and metabolism-boosting sweat sessions Calliet prescribed for his client.

Jordan’s body was put to the test, jumping from one exercise to another with little rest in between. It would be a set of bench presses followed by squat thrusts, then pull-ups, jumping rope and plyometrics, among others.

“He was running the gamut of everything,” Calliet said.

Also, he was running. And boxing, of course.

“We boxed a lot because the choreography required a lot of conditioning.” Jordan’s training wouldn’t end when filming began. Rather, he had to train to handle the rigors of being in the ring all day to learn and perform the various boxing moves you see on the big screen.

It’s the SAID principle: specific adaptation to imposed demands. If the adaption you desire is the ability to box, the demand you impose is … boxing. And lots of it.

During those four months, Jordan trained with Calliet an average of six hours a day, taking only Sundays off. Motivation was never an issue.

“It wasn’t hard because we had no choice,” Calliet said. “We had one job to do — get his body ready to look and be the part — and no one else could do it. We couldn’t fail.”

Unlike many fad diets that have been popular over the years, Calliet had Jordan chewing his carbs rather than eschewing them. It was the fuel necessary to provide energy for all that high-intensity training.

And the efforts paid off.

“He held that physique and conditioning for 27 days straight of filming,” Calliet said of Jordan’s boxing in front of the camera. “That’s a long time to hold your body at that level. He did it by being in the ring for 12 hours a day, every day.”

Alas, it didn’t last. “He lost all the muscle after filming was done,” Calliet said.

James Fell is a certified strength and conditioning specialist. His website is bodyforwife.com.

health@latimes.com