This Common Mistake People Make When Doing Leg Lowers Wrecks Your Core Work

You can work your core muscles in almost any direction, doing standing abs, sit-ups, planks, and crawls. But if you’re experiencing lower back pain from core exercises that you do while lying down, you’ll want to fix your form.

Feeling soreness in your lumbar spine, or the vertebrae of your lower back, is extremely common with ab-focused moves like the leg lower exercise, flutter kicks, and scissor kicks. All of these involve lying down on your back and moving your legs without them touching the ground. While they’re considered productive, ab-strengthening exercises, many people make this all-too-common mistake time and time again: arching the lower back during the move.

“The most common mistake I see people making in class is not pinning their lower backs to their mats,” says Heather C. White, trainer and founder of Trillfit. “When your lower back isn’t planted, you’re not fully engaging your core, and over time this can lead to prolonged stress on your back.” You’ll know if this is happening to you if you feel more uncomfortable pain in your lower back than good soreness in your ab muscles after doing these exercises.

If you do these moves correctly, you’ll benefit from a stronger core. “With proper form, flutter kicks, leg lowers, and jackknives [another lay-flat ab move] are incredible for the lower abs,” says White. When your back isn’t firmly on the mat the entire time, you’ll not only hurt your spine, but you won’t be doing anything for your ab muscles. “Just because you can move your legs lower to the ground doesn’t mean you have stronger abs,” says Rebecca Louise, mindset and fitness coach and author of It Takes Grit. “It’s all about how engaged your core is.”

To do the leg lower exercise correctly, lie on your mat with your legs straight in the air and your feet flexed. As you pin your entire back to the mat and engage your abs, slowly lower either both legs together or one at a time towards the floor without touching the ground, and lift back up. “If you need extra support, you can place your hands together in a triangle position with your fingertips touching beneath your back as you do the exercise,” says White. Or you can place a towel underneath your lower back in line with your belly button. “Tuck your hips under, and pull your belly button into your spine so the towel doesn’t move,” says Louise. “As soon as the towel starts to slip, you’ll know you’ve gone low enough.”

For more back-friendly core work, try this 8-minute plank series workout that’ll have your abs quaking: