If I say “core workout,” what’s the first thing that comes to your mind? A lot of movements aimed specifically at those visible abdominal muscles? Well, today I’m going to lead you through a core workout that involves your entire core—not just your abs. Flexion is when you bring the pelvis to the ribs or the ribs to the pelvis. For example, in this workout, we’re going to go pelvis to ribs with a seated reverse crunch. With anti-flexion, on the other hand, we don’t want the hips to move toward the ribs or vice versa. In this workout, a solid plank achieves that goal. As for rotation and anti-rotation, the first involves twisting your torso to work your core, whereas the latter requires you to engage your muscles to prevent rotation in your core. Ready to put these principles into practice? Try the quick workout below! I recommend moving through the sequence two or three times total and adding it to your routine a couple of times weekly. That said, even once a week is totally enough to get every part of your core burning! Your 4-week challenge: Over the last four weeks, I’ve shared a different strength-training workout that focuses on a specific exercise principle—to help you strengthen your mind and body all at once. I challenge you to make it a goal to incorporate these routines two to three times per week.