Squats are to leg day as sheet masks are to #selfcaresunday: essential. As many face mask options as there are in the world, there might be even more variations of the classic booty-building move. There are goblet squats, sumo squats, barbell back squats, jump squats, and loads more. Trust us, squats aren't going anywhere soon—but there’s one variation your routine may be missing.

Enter: The Bulgarian split squat—also referred to as the rear foot elevated split squat or just simply a split squat. “Bulgarian split squats are one of the best movements for developing glute, quad, hamstring, and core strength because it’s a unilateral exercise—meaning that it works and strengthens one leg at a time,” certified personal trainer Quianna Camper, a trainer with RSP Nutrition, tells Health.

Why is unilateral leg training such a big deal? According to physical therapist and certified strength and conditioning specialist Grayson Wickham, founder of Movement Vault, it comes down to compensation. “Most people are not perfectly symmetrical. So their right leg or glute might be stronger than the left, which means when you do a normal squat, the stronger side will compensate," he says. "Single-leg exercises like the split squat can help fix those muscle imbalances by developing that lower-body and core strength symmetrically.” Some research even suggests that unilateral exercises are more effective for building strength than bilateral movements like the standard squat. (Talk about upgrading your leg day).

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Because you need to activate your core during Bulgarian split squats in order to keep your chest upright, Camper says, “they also help you build core strength, and the benefit of that is that it improves your overall balance and stability.” Translation: Add Bulgarian split squats to your routine and you’ll sculpt a peach, strengthen your quads and core, and decrease risk of falling (and therefore injury) as you age.

Ready to feel the booty burn? Below, Wickham and Camper walk you through how to do a Bulgarian split squat, plus a few variations of the super-effective single-leg move.

How to do a Bulgarian split squat

Start standing with your feet hip-width apart, facing away from a box, bench, or chair that is no higher than your knees. Extend your left leg back and put the top of your foot (aka laces down) on the box. If this is uncomfortable on your left ankle, you may want to pad your left ankle with a yoga mat or towel. Then, readjust your right leg so that you're standing 12–24 inches in front of the box, hips squared forward. This is your starting position.

When you’re ready to begin, tuck your tailbone, engage your core, and draw your shoulders back. Keeping your chest up, lower your hips into a front lunge position by bending your right knee and dropping your left knee straight to the ground.

Continue lowering until your right thigh is parallel to the ground—or as low as you can go without feeling something you'd describe as "strain," Wickham says. (If you lack hip mobility, you may start to feel an intense stretch before you get very low, so stop descending and return to start.)

Once at the bottom, drive up through your right heel and straighten your right knee to return to the starting position. That’s one rep. Repeat for 8 to 10 reps before switching legs.

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To make it easier: Start with a basic split squat

Elevating your rear foot requires a ton of balance and stability, which means it necessitates a prerequisite level of core, glute, and quad strength. That’s why Camper recommends working up to it by first mastering the basic split squat.

“Start by standing in a staggered-stance position, with your feet hip-width apart and right foot about two feet in front of the other. Place your hands on your waist and square your hips forward. Then lower your body until your knee touches the floor, and come up into start position contracting your legs and glutes,” explains Camper. That’s one rep. She suggests doing 12 to 15 reps before switching legs.

To make it harder: Add weights to your Bulgarian split squat

If you have strength-training experience, Camper says you can try adding weight to kick things up a notch. “Just make sure you can do 3 sets of 15 reps on each leg [with your body weight] before playing around with weights," she says.

According to Wickham, there are lots of ways to add weight to a Bulgarian split squat. You could hold a dumbbell in each hand, one weight in front of your chest, or even use a barbell on your back, he says. The added resistance of any of these variations will help you target the glutes.

Whichever weight you grab, be sure to pay extra attention to keeping your shoulders back and down and your chest up, Wickham says. Dumbbells and kettlebells make for easier weighted options; when you're ready to try a barbell split squat, he suggests starting with an empty barbell first and slowly adding weight from there. (Because of the box or bench behind you, bailing with the barbell can be dangerous. “Choose a weight you know you can hit,” advises Wickham.)

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How to add Bulgarian split squats to your routine

Try to incorporate split squats every other time you do leg day, says Camper. “Either do them in place of your back or front squats, or do them first,” she says. While form is always important when you squat, doing split squats with tired muscles can lead to injury if you’re not extra careful, she adds.

Both Camper and Wickham recommend pairing split squats with deadlifts, glute bridges, wall balls, or dumbbell box step-overs—or core exercises like planks, bird dog, or dead bug.

However you add split squats to your workout regime, as long as your form is sound, your booty will thank you.

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