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"Get down on all fours resting your forearms and knees on the floor," says Dede Lagree, owner and head trainer at Lagree Fitness Studio
who has worked with Ashley Graham, Viola Davis, Elsa Hosk, and Bella Thorne. "Then step your feet back to a plank position. Contract abs to keep your body in a straight line and spine parallel to the floor. Abs should be pulling toward the ceiling. The key is to hold it for as long as you can." Lagree recommends starting out by holding for 20 seconds and working your way up to a minute, or longer. Come down to starting position, rest and repeat three times. Want to kick it up a notch? Here's a look at some plank upgrades
"Lie on your left side with your left forearm on the floor perpendicular to your body and your right hand resting on your side or on your hip. Legs should be out straight and feet slightly scissored one in front of another. Pull your belly button in towards your spine. Raise your body up by straightening and lengthening the waist so that you are balanced on your left forearm and the bottom of your left foot; once balanced, lift arm up." Lagree recommends holding for 20 seconds and working your way up to a minute. Rest in between, and repeat three times on each side. Here's how to get a flat belly without a lick of exercise
"To start, sit on the floor with your knees bent and heels about a foot away from your body. Then, slightly lean back without rounding your spine—this part is particularly important (and hard), but don't let your spine curve or the exercise won't work. Hold a weight with both hands in front of you, elbows bent. Then while pulling your belly button to your spine, twist slowly to one side. Hold for three seconds and inhale, then rotate to the other side." Lagree recommends trying to complete as close to 16 full rotations as possible
"Position your body in plank. Pull your right knee into your chest. As the knee draws to the chest, pull your abs in even tighter to be sure your body doesn't stray from the plank position. Then, quickly switch and pull the left knee in. At the same time, you push your right leg back, pull your left knee in to the chest. Continue switching knees so that you are creating a running-like motion. A common misconception is that mountain climbers have to be done fast. Rather, whatever your speed, be aware of your body positioning and core stabilizers." Lagree recommends three one-minute intervals with short rests in between. Side note: Mountain climbers are great for preventing knee pain
"Lie down on the ground, making sure that your lower back is fully pressed down. Lock your hands together behind your head. Then, bring knees into the chest, and lift up your shoulder blades. Straighten your left leg to a 45-degree angle while turning your upper body to the right, bringing your elbow to the knee. Make sure that your core is engaged and rib cage comes with the elbow. Switch and repeat on the other side. Focus on doing this exercise slowly and controlled so that you're engaging all core muscles. Lagree recommends trying for 20 repetitions (both sides counts as one rep).