A behind-the-scenes video showcases Charlize Theron’s intense training for The Old Guard. Based on Greg Rucka and Leandro Fernández’s graphic novel, The Old Guard follows a group of immortals who use their regenerative abilities to help people around the world. It has become one of Netflix’s most-watched films of all-time, being praised for its action sequences and Theron’s performance.

Theron plays the leader and oldest of immortals, Andromache “Andy” of Scythia, in The Old Guard. The 44-year-old actress has more than cemented herself as an action badass in the past by playing fighters like Mad Max: Fury Road’s Furiosa and Atomic Blonde’s Lorraine Broughton. She plays her most formidable character yet in The Old Guard. Having lived for centuries, Andy is described as having “forgotten more ways to kill than entire armies will ever learn.”

Related: The Old Guard: How Old Andy Really Is

Theron, along with fight coordinator Danny Hernandez, details her intense training in Netflix Film Club's “Training Day” featurette. Theron worked with fight coordinators on her striking motions for 3-4 hours a day in preparation for The Old Guard. To meet the demand of the shoot, she built her upper body strength, trained in martial arts, and practiced with firearms and a variety of melee weapons (from swords to axes). The full clip can be seen below:

Netflix’s video briefly addresses the fighting we see Theron do on horseback in flashbacks. Even the hours spent on those scenes is testament to work that went into crafting all of the film's thrilling action sequences. While The Old Guard is director Gina Prince-Bythewood’s first action outing, Hernandez is a prominent stunt coordinator. He has worked on such blockbusters as Avengers: EndgameBirds of Prey, and Venom. His experience, coupled with the confidence and tenacity of Theron, translates on screen.

Andy and the other immortals’ fighting prowess is acknowledged by everyone in the film. At one point, Chiwetel Ejiofor’s James Copley tells executives looking to utilize/monetize immortality that “these are extraordinary individuals. They are extremely resistant to capture.” Theron had to deliver the action goods for the audience to suspend their disbelief, and she does. Her character sustains minimal damage and outclasses several heavily-armed opponents with nothing but an axe, which wouldn't have looked real had Theron not trained as hard as she did. While Theron is highlighted in the video above, all of the actors playing the immortals clearly stepped up to the plate when it came to training for fight sequences, and it shows in the final cut of The Old Guard.

More: The Old Guard Ending & Sequel Setup Explained

Source: Netflix Film Club