When a video featuring actor Sivakarthikeyan's workouts and heavily built-up physique was out early this year, many wondered what he was up to. Thanks to the sculpted, athletic look, the well-defined 'back pose' he struck in the video was also circulated widely on social media. Though it was known that he was working for director Rajkumar Periasamy's film based on the life story of Major Mukund Varadarajan, not many were aware that Sivakarthikeyan or SK, who plays the late army man in the film, had never weight-trained or strength-trained before taking up this project.

On the day the film Amaran hits theatres and is surging ahead with great reviews, here's what you should know about SK's hard work behind building his body for the movie. The film Amaran is also trending on Google Trends, with more than 100K search volume in the past 21 hours. From 'only cardio' to all-things-army While its lead actress, Sai Pallavi, had to work hard to emote its Tamil-speaking Malayali heroine, actor Sivakarthikeyan had to put in some major effort in the gym to look the part.

Interestingly, he weighs differently at each of the story stretches! The sequences in which he is training for the military have him at around 72 kgs, around 75 kgs for the Captain's portions and almost 80 for the part in which he plays the Major in the army. In various videos released by the Amaran team, the audience also sees his 100-day transformation to become Mukund. According to his trainer Sandeep, Sivakarthikeyan .