DWAYNE 'THE ROCK' JOHNSON wanted to be in the "best shape of his life" for 'Black Adam.'

The 50-year-old actor stars in the upcoming superhero movie and explained that because it was the "most important" role of his career to date, he felt compelled to change his diet and maintain his peak physique during the four-month shoot.

He said: "This was it for me. This is the most important role of my entire career that I've been so lucky and blessed so I wanted to be in the best shape of my life. I felt like 'Black Adam' commanded that. I changed my diet around, my training. The challenge is when you peak your body to a certain point, the challenge is then maintaining it for the next four months, which was hard. It was a lot of stress on the joints but I think it was well worth it and that's what you see - that passion and that work ethic on screen."

The 'Red Notice' star went on to describe himself as a "gym rat" but admitted that the training he went through for his latest project was even more "fine-tuned" than what an Olympic athlete might endure.

Speaking on UKTV show 'This Morning', he added: "I do like to try and stay and shape. I love working out, I'm a gym rat. But the training for 'Black Adam' was more fine-tuned and it became really scientific. The training was fine-tuned, and the volume became more fine-tuned with the training. So for example, elite athletes who prepare for the Olympics, a championship, or anything like that will train very hard with their coaches and then they will peak. Then they have to maintain that for a night or maybe a week or two. But the idea of maintaining it for four months, that's where the science and detail come in. The minutiae that we don't think about - and we shouldn't have to think about it every day - but it's like pulling sodium at the right time or pulling water at the time."