Zac Efron Details His 'Shocking' Physical Transformation For 'Iron Claw' Role (Exclusive)

For his bulked up role inThe Iron Claw, star Zac Efron brought the legendary and groundbreaking pro-wrestler Kevin Von Erich to life on the big screen -- a challenge that truly took a lot of effort and help to accomplish.

Efron walked the red carpet in an ivory suit by Reiss at the Dallas premiere of the new wrestling biopic drama, at the The Texas Theatre on Wednesday, and he spoke with ET's Cassie DiLaura about his experience becoming the famed figure.

"This movie's a true story, and that man, Kevin Von Erich right there, he really motivated me to get in shape for this movie," Efron said of the real-life figure he portrayed, who was also in attendance at Wednesday's premiere.

"The physicality he brought to the ring every single day was really unique. It changed wrestling," Efron continued. "I knew that was going to be the hardest [thing] for me to master and get right. So, I put everything I had into it"

And it seems to have paid off. As Efron explained, "He told me he was happy with it last night, so I'm stoked! I cried a little bit, if I'm going to be completely honest."

Apart from getting in peak physical condition, the role also required Efron to rock the famed wrestler's bowl cut 'do and notably wrestling attire.

"It was shocking at every point of the transformation," Efron said. "I remember Harris [Dickinson] and I were walking out of hair and make-up and it was like the first time we had to wear the full kit, and we were both thinking, 'What the hell are we doing here, man? How did we get into this?'"

"But I think it ended up looking really good and we had a great crew helping us out with that," Efron added. "The hair and make-up team was epic."

The Iron Claw follows the Von Erich family, led by patriarch and coach Fritz Von Erich (played by Mindhunter star Holt McCallany), and his sons -- Kevin Von Erich (Efron), David (Dickinson), Kerry (Jeremy Allen White), and Mike (Stanley Simons).

The Von Erich brothers spent the majority of their careers in World Class Championship Wrestling (WCCW), where they won multiple individual and tag team titles. The family was a pro-wrestling dynasty in the 1980s, who found both triumph and tragedy in and out of the ring.

The brothers' untimely fates (five of Fritz's six sons would precede him in death) led many wrestling fans to mythologize the idea of the "Von Erich curse."

The Iron Claw hits theaters on Dec. 22.

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