Sydney Sweeney’s Kickboxing Roots Fueled Her Breakout Boxing Role In ‘Christy’

Sydney Sweeney’s revelation about her kickboxing background has emerged as a crucial element in her preparation for portraying boxing legend Christy Martin in the upcoming biopic “Christy.” The actress recently disclosed how her childhood martial arts experience provided the foundation for her dramatic transformation into one of boxing’s most celebrated champions.

​Sydney Sweeney’s Extensive Combat Sports Training from Youth

In an interview with TalkSport, she explained:

“So, I had the pleasure, like you said, of working with Christie. She actually would get in the ring with me and sparred a few times and she would help walk me through different techniques. And also being able to watch all of the fighting footage, I was able to look at her past fights.

“I grew up kickboxing, grappling, so I was a fan of the sport as well. But what’s a cool thing is every single fight that happens in the movie is the exact fight in her real life. So like her Diego fight, her Leila Lee fight, every combination you see, they’re the real combinations from her actual fight. It was intense. Our our fight choreographer uh Walt, he was absolutely amazing. Like he truly took to detail every single move of Christie’s, how she would turn her head, where her foot stances were. We were there was a lot of care to detail the entire time.”

Sweeney began training in martial arts at an early age, developing skills that would later prove invaluable for her boxing role. From ages 12 to 19, she dedicated herself to grappling and kickboxing. Her martial arts journey extended beyond basic training, with Sweeney competing in grappling tournaments where she was often the only female participant.

​The actress trained at Gokore Highest dojo from age 13 until approximately 18 or 19, where she faced the unique challenge of being the sole girl in an all-male environment. During competitions, she successfully defeated male opponents who competed in weight categories above her own. Her diverse combat sports background included taekwondo, jujitsu, grappling, and kickboxing, which she began practicing at age 5 to help manage her hyperactivity.

For her portrayal of Christy Martin, Sweeney underwent an intensive three-month preparation period that mirrored her earlier athletic dedication. She gained approximately 30 pounds and followed a rigorous daily schedule that included morning weight training, midday kickboxing sessions lasting two hours, and evening strength conditioning. The transformation required her to increase from a size 23 to size 27 in jeans while developing the muscular physique necessary to authentically portray the boxing champion.

​Her diet during preparation included calorie-dense foods, protein shakes, and frequent meals at establishments like Chick-fil-A, combined with constant physical activity that burned through the increased caloric intake. Sweeney described feeling “crazy strong” throughout the process and expressed genuine enjoyment of the physical demands.

The subject of Sweeney’s portrayal, Christy Martin, established herself as a pioneering figure in women’s boxing during the 1990s. Known as “The Coal Miner’s Daughter,” Martin became the first female boxer signed by legendary promoter Don King and was the first woman to appear on the cover of Sports Illustrated.

​Martin’s professional career spanned from 1989 to 2012, during which she compiled a record of 49 wins, 7 losses, and 3 draws, with 31 victories by knockout. She held the WBC female super welterweight title in 2009 and was inducted into the International Boxing Hall of Fame in 2020, the first year women were eligible for the ballot.

Director David Michôd and co-writer Mirrah Foulkes crafted the biopic to address not only Martin’s boxing achievements but also her survival of domestic violence and a near-fatal attack by her husband and former trainer in 2010. The film, set for theatrical release on November 7, 2025, features Ben Foster as Jim Martin and includes a cast that brings authentic depth to Martin’s story.

​Sweeney’s commitment to authenticity extended to performing her own fight scenes, resulting in real injuries including concussions and bruises during filming. Producer Kerry Kohansky-Roberts confirmed that Sweeney and other actors sustained genuine physical impacts to maintain the film’s realistic portrayal of boxing.

The role proved transformative for Sweeney beyond the physical aspects. She described how portraying Martin taught her to “stand up for myself more and feel stronger in my personal life”. The actress developed a close relationship with Martin during filming, with the boxing champion frequently present on set to provide guidance and authenticity to the production.

​Martin praised Sweeney’s dedication to capturing both her aggressive fighting style and her naturally reserved personality outside the ring. The collaboration between actress and subject created what Sweeney characterized as a “powerful experience” that extended beyond typical actor preparation.

​The film premiered at the Toronto International Film Festival on September 5, 2025, where it received a standing ovation and brought Sweeney to tears during the emotional moment. Critics have noted Sweeney’s complete transformation, with reviewers highlighting her ability to disappear into the role through changes in hair color, eye color, accent, and physical presence.​