Charlize Theron would ''roll in the sand'' to get ready while filming 'Mad Max: Fury Road'.

The 39-year-old actress features as Imperator Furiosa in the upcoming action movie and would prepare for shooting by covering herself in dirt in the arid landscape of Namibia to ensure she looked like she was living in a post-apocalyptic world.

She said: ''I got to show up 20 minutes before we went on set and I would walk out of my trailer in my wardrobe and roll in the sand, literally just roll.''

Charlize also took other deliberate steps to prepare for the role, including getting a buzz cut hairstyle which she had clipped every three days during filming.

Director George Miller recalled: ''She called one day and said, 'I'm thinking of getting a buzz cut.' The moment she said that, I just thought, 'Brilliant.' ''

Charlize - who is in a relationship with Sean Penn - also ensured she gained weight to play the character because she didn't want to look ''scrawny'' opposite co-star Tom Hardy, who is taking on the titular role made famous by Mel Gibson.

She told Total Film magazine: ''I wanted to look like I had tremendous upper body strength because there was so much physicality in the movie - especially with someone like Tom Hardy. I just hate that idea of scrawny little girls fighting men off and then winning. I looked like a football player in this movie!''