Here's how Alicia Vikander gained 12 pounds of muscle in preparation for 'Tomb Raider'

The latest interpretation of Lara Croft – the video game character that won hearts with her fierce will and incredible agility (and maybe her mini shorts too) – has just been released in cinemas. This time around, Swedish actress Alicia Vikander took on the role in the new Tomb Raider, following Angelina Jolie's version of the character back in the early 00's.

For many, it was a surprise that the Ex Machina actress was cast as the action hero – she's rather short, standing at 5'5" (1.65m), which left people questioning whether she could pull off the more physical feats expected of the character. But Alicia defied all doubts and bulked up massively, following an intense regimen to build up her strength like never before.

"I wanted her to be a very strong physical girl," Alicia said of her transformation during a promotional event. "This was the first time that I really weight trained. I think a lot of girls are intimidated by it, but I felt empowered lifting like that."

She gained a total of 12 pounds (5.5kg) of pure, lean muscle – quite a feat for someone so small. The 117-pound (53kg) actress worked with trainer Magnus Lygdback who guided her through intense training to bulk up for the role. Magnus has also worked with the likes of Alexander Skarsgard for his role in Tarzan, as well as Wonder Woman's Gal Gadot.

Magnus told Men's Health that Alicia was very determined and dedicated: "Alicia had an incredible work ethic, which comes from her past as a ballerina. She was already strong going into this process, but she wasn’t ‘Lara Croft’ strong."

To achieve this level of fitness, Alicia followed the Magnus Method program – an interval-based workout plan focused mainly on strength training, including squats, pushups and chinups, as well as heavy weight lifting. She also followed an intense core workout program to sculpt her abs, and incorporated Lara Croft-esque skills like rock climbing and mixed martial arts into her training too.

"No matter where we were in the world we found cliffs and rock walls for Alicia to hang off of," Magnus said. "We hadn’t seen the script yet, we didn’t have particular scenes to rehearse, but we were able to anticipate the kind of action that she would be doing because of the character."

They started three months before shooting began, and judging by videos of the 29-year-old working out, it looks like there was no need for a stunt double!

As well as her intense workout regime, Magnus advised Alicia to follow a strict keto diet in order to bulk up. "Since we were travelling so much over the holidays, we decided the keto diet would be best because it’s easier to control the macros that way," he told PopSugar. The keto diet is a high-fat and low-carb eating plan that forces the body to burn fat rather than carbs, therefore helping muscle growth and preventing fat gain.

"It’s always tricky the first couple of days, but [Alicia’s] willpower is just unbelievable and she didn’t complain, even though I could see she was struggling a little bit," Magnus said. And it certainly paid off - I mean, just take a look at those well-defined muscles!

"There aren’t many people out there who would have been able to keep up with her in the gym," Magnus said of Alicia.

Could there be anyone more perfect to play the role of Lara Croft?