There’s no greater advert for personal trainer Magnus Lygdbäck’s services than the promotional poster for The Northman (especially since it doesn't have a pesky title blocking your view). There, staring you down on your morning commute like you’ve just spilled a cortado down his favourite tunic, you’ll see Alexander Skarsgård looking, somehow, beyond all reason, even more ripped than he did as Tarzan six years ago.

It was Lygdbäck who transformed the Swedish actor into the king of the jungle back then, and so he was the only man who came to mind when Skarsgärd won the role of axe-wielding warrior prince Amleth in Robert Eggers’s Viking epic, which reached cinemas last week.

“They had planned this movie for a long time because Alex talked about it years ago,” Lygdbäck told us. “He contacted me and said, ‘It’s happening, are you in?’” He was, unsurprisingly, in.

alexander skarsgard workout
Aidan Monaghan

So they got to work on the character, talking about the different creatures that Skarsgärd wanted to embody. “His spirit animal in this movie is a bear and a wolf. We wanted the size and strength of a bear, but we wanted him to move like a wolf,” Lygdbäck says. “You can see that he’s hunching over in the movie like an animal, like a bear. We wanted him to be thick but not necessarily as cut as in Tarzan.”

Sadly, the Vikings didn’t survive long enough to set up YouTube fitness channel. Traditional workout plans were in short supply. “As a Swede you get taught in school about Viking mythology, so I do know more than the average person to begin with,” says Lygdbäck. “I learned a lot on this movie, but nothing that affected our training.” Instead, he fell back on his tried and tested methods.

“My approach is to build a character. It means you have to integrate movements and skills that your character needs into strength training,” Lygdbäck, who has previously trained A-listers like Harry Styles, Ben Affleck and Alicia Vikander, tells us. “I like to do a 4-day split normally with my male actors. Which means you target each muscle group much harder and then allow it to rest while training other body parts. Strength training is the main focus.”

Luckily, the pair were afforded enough time to fully commit to building Skarsgård's body. “We trained for 6 months to prep. If you get less than 3 months then you can’t do a build-up and a cutting cycle, you have to do one long lean mass gaining cutting cycle. When you get more than 3 months, like we did, you can do 2 training cycles. The build-up and the cutting.”

“The challenge is always to get enough rest and to get the training in in the mornings once you start filming because the turnaround is so short.”

So how did the fitness program differ to Tarzan?

“We did less HIIT training this time and more strength training. We did lower reps to get stronger,” says Lygdbäck. “We integrated a lot of shoulder and hip stability/mobility work to prepare him for swinging an axe and running around. Alex is the hardest worker in the room, that’s why he looks that way. He makes my job very easy. He should have the credit for this, not me.”

You can complete Lygdbäck's full workout plan for The Northman by checking out the Magnus Method on the Playbook app.