When I saw Blue Crush for the first time at a middle school sleepover, all I could think was 1) I need to learn how to surf and 2) Holy Hawaii—how do they strengthen their abs? Because riding those waves looks hard.

Surfing, in general, requires a level of core strength comparable to that of the Greek Gods, who are somehow always parading around shirtless in old paintings. Everything from “paddling out” to “popping up” to actually riding a wave requires some serious attention from your core, and let me tell you—it is no joke.

So when I had the chance to sit down with professional surfer Alessa Quizon—a Billabong-sponsored athlete who happens to be one of the top competitors in the world—I could hardly contain my excitement in asking about her workout routine. In fact, I believe my exact words were, “So like, you must have the strongest core on the planet. HOW?!”

Her routine,  she tells me, is a combination of a few different things: surfing for six hours a day, every day, and supplementing her in-water routines with a style of jiu-jitsu that has become popular among surfers. “It’s this idea of using your body consistently. You rest, but every movement is getting you ready for the next move, so that’s what I liked about it. It has good momentum and you use every part of your body. It’s like yoga, but with a little more intensity.”

Then, there are her four times-a-week personal training sessions, where she really works on building up her core. “I love planks, any type of planks,” she says, noting that she tries to stay away from any variations with impact (like plank jacks) to give her shoulders a break when she’s not on the board.

Here, Quizon shares the five moves she loves for keeping her abs surf-level strong.

High planks: Place your hands on the floor shoulder width apart, and rotate your elbows out while turning your hands in. Press away from the floor, keeping your spine neutral by tucking your ribcage and pelvis into a hollow position. Squeeze your quads, glutes and core as hard as you can to get the full effect of the move, and don’t forget to breathe.

Shoulder taps: Holding your high plank position, alternate lifting your hands and tapping alternate shoulders (so, the left hand raises and taps the right shoulder, and vice versa). Keep squeezing those muscles.

Russian twists: Sitting on the floor, lift your legs off of the ground and lean your torso back so you’re balancing on your butt—kind of like you’re making a human V. Engage your core with your hands in front of your chest, and twist from left to right without letting your chest or legs fall. Try to get your hands as close to the floor on either side as possible, but don’t feel like you need to rush through the move. To amp up the intensity, hold a weight to your chest.

Weighted suitcase sit ups: Holding a weight to your chest (Quizon usually opts for a 12-pound dumbbell), lay on your back with your legs straight and extended off of the floor in front of you. At the same time, lift your upper body into a crunch and tuck your knees to your chest. Lower your upper body back onto the floor and extend your legs long so they’re hovering a few inches above the floor.

Mountain climbers: Start in a high plank with your abs, glutes and quads engaged, and pull your knees one at a time into your chest. Turn it into a cardio blast by moving as quickly as possible (without sacrificing form, of course).

Bicycle crunches: Place your hands behind your head and lift your torso off of the ground and extend your legs out straight, a few inches off of the floor. Pull one knee at a time into your chest, twisting your upper body to touch it with your elbow.

Get a surfer-strength core of your own with this 12-minute at-home workout from Emily Turner. Plus, we finally figured out which was more effective for building strength: Crunches or sit-ups.