Photograph by Igor Polzenhagen

That’s you’re entire midsection… covered.

Your workout is missing this exercise! This resistance move is super popular with fitness trainers as well as yoga and Pilates instructors because it’s simple yet strengthens your entire midsection. It’s a chain exercise that engages your abs but offers even more benefits for your butt, hips and lower back, says master trainer Garson Grant.

READ MORE: This Total-Body Strength Move Will Make You Feel Like A Total Badass

The bridge builds muscle, boosts flexibility and can also be easily incorporated into any routine. Here’s the basic pose, plus a few advanced spins. Start by aiming for three sets of 15 to 20 reps.

Basic Bridge

Lie on your back, knees bent, feet flat on the floor hip-width apart, arms relaxed at your sides. Lift your glutes off the floor, pushing with your heels, so your body looks like a straight line from your knees to your shoulders. Squeeze your glutes and abs, hold for two seconds, then take three seconds to slowly lower back to the floor to start. “Make sure you’re extending your hips, not your back, and also that you aren’t tightening your shoulders so they come in closer to your ears,” says Grant.

READ MORE: The 4 Tightest Muscles – And Exactly How To Stretch Them

Alteration: Hands-Up Bridge

Get in the basic bridge position, but this time do the move with your hands directly in the air; it forces you to engage your abs and glutes more.

Alteration: Unilateral Bridge

Go back to the basic bridge position, but this time raise one knee to your chest or extend it all the way out, then start lifting your glutes off the floor as with a basic bridge. Working the muscles on one side of the body helps isolate them and make them stronger.

These are the 3 worst exercises you can do if you have sore knees. Plus: Your ‘no running required’ weighted cardio plan.