That's majorly thanks to the help of her badass trainer, Melissa Alcantara. The duo trains together six days a week at 6 a.m., for an hour to an hour and a half each session, Alcantara tells WomensHealthMag.com.
Of course, core work come into play during basically all the moves they do. (Kim's all-time fave is the hamstring curl machine, which strengthens the hamstrings, glutes, and core.) But "we'll have one day entirely dedicated to abs," she says.
And Alcantara is letting WomensHealthMag.com in on one of Kim's go-to routines. Here, she demos a simple three-part abs workout that Kim does as part of their weekly gym routine, or while she's traveling. "It's simple, yet effective at the same time," Alcantara says.
Whether you crank out this workout on your own dedicated abs day, or fit it in after a run, this efficient routine is definitely worth a go. (Again, have you seen Kim's abs?! But we digress...)
LYING LEG LIFTS
For this move, be sure to "push your lower back flat on the floor, and keep it there," says Alcantara. She also recommends lifting your chest up slightly to maintain head and spine alignment. "From this position, your abs will already be engaged."
How to: Lie on your back with your palms facing down, planted underneath your butt cheeks. Raise your legs and chest a couple inches off the ground, keeping legs straight and neck aligned with chest. Inhale as you slowly lift your legs to a 90-degree angle, keeping legs straight. Pause, then exhale as you lower your legs back down. That's one rep. Do four sets of 12 to 20 reps.
REVERSE V UPS
"If at any point you feel like you’re rounding or hyperextending your lower back during this move, then reset and start again," says Alcantara.
How to: Start in a plank position and make sure your wrists, forearms, and shoulders are aligned straight (check out my plank video on Youtube). Exhale and use your legs to jump into the reverse V-position (or pike). Then inhale and jump your legs behind you, landing back into a plank position. That's one rep. Do four sets of 12 to 20 reps.
ABS BICYCLE WITH CLAP
"This one is really fun!" says Alcantara. But, again, "if your lower back starts coming off the floor, then reset and start again with good form."
How to: Lie on your back, with your lower back pressing into the floor. Then raise your chest slightly, and make sure it's aligned with your neck. Lift both legs off the ground. Exhale as you bring your left knee in towards your chest, curl your body towards that knee, and clap your hand underneath your knee. Then inhale as you bring it back to the starting position and repeat with your right leg. That's one rep. Do four sets of 12 to 20 reps.
This article originally appeared on Women's Health US