Ladies and gentlemen, let’s talk about three-ways. No—not the kind that happen in the bedroom (sorry to disappoint—though you can find that story here), but rather the kind that happen in the gym and hit every muscle in your core.

Most of us think of our “abs” as the general section around our stomachs, but in reality, the core is made up of (at least) 11 different muscles. These muscles, which wrap around your trunk, are divided into three major sheaths: Your upper abs, your internal obliques, and your “deep four” (which includes the pelvic floor, diaphragm, multifidus, and transverse abdominis). In order to strengthen your core to its full potential, you’ll want to work each of the three sections individually by way of a three-way abs workout that will hit them all.

Chances are, you’ve probably been doing these types of workouts forever without realizing it. “Moves like your standard crunches and sit-ups are upper abs movements, whereas lower abs moves involve moving your legs with things like leg raises and scissor kicks,” says Rhys Athayde, founding trainer and chief experience officer at Dogpound. “As for working your obliques, it’s about isolating one side and actively engaging and crunching it with something like a side plank or a leg raise.”

For maximum benefits, he suggests mentally splitting your abs into different sections and working them one by one. “I recommend taking one specific part of your abs and concentrating on that for a lengthy period of time, the way you would any other muscle,” says Atahyde. “That way, you’re working those muscles to the hardest possible condition and making sure that they’re activated before moving on.” So, for example, instead of alternating between your right oblique and your left oblique, fully work one side to exhaustion and then repeat the routine on the other side.

That said, there is one hero move that’ll get your entire core working hard: A good, old fashioned plank. Start with a hold, which will fire up your upper and lower abs at the same time, then add some hip dips (otherwise known as a “rainbow plank“) to hit your obliques. You can also mix and match individual moves—for example, pair a standard, straight-leg crunch with a leg raise and a scissor kick—which engages all three spots at once.