How Zac Efron’s ‘wildly uncomfortable’ Iron Claw preparation pushed the actor to the limit – from eating every TWO hours to training so hard he couldn’t breathe for days

Zac Efron has revealed how tough his preparation for his new film Iron Claw was, describing it as 'extremely uncomfortable'.

Created by Sean Durkin, the wrestling drama revolves around the true story of the Von Erich wrestling family.

The film portrays the meteoric rise of Texas brothers Kevin (Zac Efron) and David (Harris Dickinson) and Kerry (Jeremy Allen White).

It will also chronicle their crushing fall as they try to keep up with that of their father, Fritz Von Erich (Holt McCallany), and his unrealistic expectations.

But adapting to the role has not been smooth sailing for Zac, who found it difficult to cope with the physical demands of the role.

Zac, left, transformed his body so much that he was unrecognizable compared to his naturally slim physique (right in 2019)

In an interview with USA todayZac confessed that he had no idea how real men could be so successful in the sport.

He said, “You think you've got it down, and you speed up a few times and your confidence builds.

'Then you hit one of those things that is just an inch too high and your rib has as good as disappeared. You can't breathe for a few days.'

He confessed that the first time he tried the sport was “shocking” because it wasn't as “easy” as it looked on TV.

Many of the wrestling matches in the film were recreations from the Von Erichs' prime against some of their rivals, Harley Race, Rice Flair and the Fabulous Freebirds.

The physical transformation into wrestling professionals seemed to be a challenge for all three actors, with Dickinson describing it as difficult and Zac joking that it was “pretty annoying” having to drag himself to the gym every day.

Jeremy said his least favorite part of their workout routine was having to eat every two hours.

But it wasn't all a challenge, as the 17 Again star himself compared the wrestling training to a “fun camp with your best brothers.”

The film portrays the meteoric rise of Texan brothers Kevin (Zac) and David (Harris Dickinson) and Kerry (Jeremy Allen White) – alongside their fall (photo: Jeremy and Harris)

Zac admitted the first time he tried the sport was 'shocking' as it wasn't as 'easy' as it looked on TV (Picture: Zac)

He said there was a “team element” to the sport and that learning a new skill allowed him to use different parts of his brain.

His co-star Dickinson described Efron as the group's “biggest cheerleader” and explained that the star always wanted them to win.

Speaking about the real-life wrestlers they play on screen, Jeremy said it was interesting to explore the bond and rivalry between the siblings.

“They reached this level of rock stars or superheroes, and not for a very long period of time, really.”

The Iron Claw stars also turned to the wrestling community for support and guidance.

Jeremy also confessed that he didn't realize that a lot of wrestling is about making each other “look good.”

The High School Musical star confessed it was 'quite annoying' to get up and work out at the gym every day (pictured Lily James as Pam and Zac)

Jeremy said it was interesting to explore the bond and rivalry between the struggling siblings, who achieved 'rock star' status in such a short time (Picture: Jeremy Allen as Kerry)

He went on to explain that it's essential to “leave your ego at the door” when participating in sports.

Many real-life professional wrestlers have appeared at various Iron Claw premieres, including John Cena, All Elite Wrestling Champion Maxwell Jacob Friedman, as well as the real Kevin Von Erich.

Despite the grueling training, Dickinson announced that he would be ready to step back into the ring with his Iron Claw castmates.

Zac added that it would be the “most electric show” but that he would need a few more weeks and a few more workouts to get his flexibility up to scratch.