Los Angeles, June 10 : Actress Sydney Sweeney has shared the 'crazy' preparation that went into essaying the female boxer Christy Martin in a new biopic set for release later this year.

Speaking to W Magazine, the film's director David Michod said the Emmy-nominated Euphoria star gained more than 30 pounds (over 13 kilos) to play the athlete, who put female boxing on the map in the '90s, covered Sports Illustrated and fought on Mike Tyson's undercard.

'I loved it,' Sweeny said of the behind-the-scenes training, reports deadline.com.

'I came onboard to play Christy, and I had about three and a half months of training. I started eating. I weight-trained in the morning for an hour, kickboxed midday for about two hours and then weight-trained again at night for an hour.'

Sweeney, who also donned brown contact lenses and a brunette wig fashioned into a mullet-like hairstyle for the role, said that her body was 'completely different.'

'I didn't fit in any of my clothes. I'm usually a size 23 in jeans, and I was wearing a size 27. My b***s got bigger. And my b*** got huge. It was crazy! I was like, 'Oh my god.' But it was amazing: I was so strong, like crazy strong.'

Amid production for the film last year, which has since wrapped, Sweeney shared the first photos of herself as Martin.

She wrote at the time on social media, 'Over the past few months, i've been immersed in training to bring to life the story of an incredible woman'a true champion who fought battles both inside and outside the ring. Her journey is a testament to resilience, strength, and hope, and I'm honored to step into her shoes to share her powerful story with you all. more to come soon.'

The yet untitled biopic, which is from a script co-written by Michod and Mirrah Foulkes, follows Martin's story as the first breakout in U.S. female boxing.

The biopic will trace her rise to fame and the abuse she faced at the hands of her then-husband, who attempted to murder her.

/IANS