(Cover) - EN Star Style - Rosie Huntington-Whiteley says "running in heels" requires a lot of work.

The 24-year-old model famously replaced Megan Fox in the lead female role opposite Shia LaBeouf in Transformers: Dark of the Moon.

Rosie says she had to prepare her body for the physical challenges on set, and also needed to accustom herself to the art of running in stilettos as she is normally used to strutting along the runway in them.

"There was a lot of running around in heels, so it was important to strengthen everything and get my balance right," she revealed in an interview with the July/August edition of Women's Health magazine.

Rosie worked with movement specialist Jason Walsh four or five days a week in preparation for the role. The stunning star has described the fitness sessions as "torturous" but says they had a massive impact on her physique.

"Jason works you hard, but it shows," she said. (C) Cover Media