Leg day is tough no matter what—but if you're Jessica Biel, apparently it's a glutes-burning, legs-shaking kind of tough.
Jessica's trainer Ben Bruno (who also trains Kate Upton and Chelsea Handler, NBD) posted an Instagram video showing the actress and wife of Justin Timberlake doing a skater squat combination that looks absolutely insane.
Even Bruno realises how intense the combination is. He captioned the post, "Wanna see something crazy?" Duh! Of course you want to see the moves that help build Jessica's famous butt and toned physique.
In the caption, Bruno explains that he challenged Jessica to spend eight seconds lowering her body into each skater squat (he calls these eight-second eccentrics). The move is so tough, it only requires six reps on each side.
Oh and BTW: This video is just a snapshot of Jessica's full workout. Bruno makes sure everyone knows Jessica is putting in the work when the camera isn't recording, too. "This isn’t something we did one time for the video either; this was her third set and I have her do these routinely," he wrote in the caption. "It’s really a wonder she hasn’t fired me yet."
Welp, Jessica jokingly commented, "You're fired," on her trainer's post. But she also shared the video on her own Instagram, so I'm thinking Bruno probably still has the job. Her caption, "Never has anyone in the history of the world counted slower than my trainer @benbrunotraining."
Jessica's hard work has certainly paid off. The 37-year-old actress and mother to 4-year-old Silas looks ripped.
This article originally appeared on Women's Health US.