Jillian Michaels Reveals The Biggest Mistakes You're Making When Doing Planks

Sit-ups can be a struggle, with all of the hustling up and down from the floor to your knees — and it can be hard to know what to do with your arms. Do you cross them over your chest or tuck them behind your head, and for that matter, do you aim for your knees or is it good enough to just pulse upward? Bicycles are an equally flustering abs exercise, with all of that criss-crossing; if you're not a fitness pro, chances are, you'll end up touching the left elbow to the left knee instead of the right at least once during a set. In comparison, the plank is beautiful in its streamlined simplicity. Prop yourself up on your hands or elbows, and hold.

Except, we often hold planks the wrong way, according to Jillian Michaels, health and fitness expert and creator of the Jillian Michaels Fitness App. In an interview with The List, Michaels explained that despite seeming easy or basic, this is one of the most commonly botched exercises people do. "There are actually quite a few things people can get wrong with their form while doing plank," she said.

First things first: The right way to plank, according to Michaels, is to place your palms flat on the ground, directly under your shoulders. Next, rest your lower body on the balls of your feet, which you should keep hip-width apart. "Make sure to keep your spine totally straight and aligned — especially your head, making sure you aren't straining to look up or allowing your head to drop down," Michaels explained. "Draw your belly button up and in towards your spine, and tuck your tailbone by squeezing your booty," she added, "as though it was tryna gobble up ya undies." Once you're in this colorfully described position, you'll want to press away from the ground — "not just with your chest, shoulders and triceps, but also your lats — being sure to engage your upper back," Michaels said.

Sounds easy enough, but Michaels said one of the the most common mistakes is having your hands too far in front of your body. She's also seen clients make this form faux pas: "Their core isn't engaged and they allow their low back to dip and belly to fall toward the floor," or, "their booty is up in the air as they shift into their shoulders, due to a weak core." You'll also risk a sub-optimal plank if you don't engage your upper back, Michaels said.