The number-one sign your abs workouts aren't working

You’re in the middle of a group fitness class and it’s time for abs. The instructor is cueing exercises like toe touches and Russian twists, explaining which area of your abs you should feel the burn.

You’ve checked your form in the mirror and everything looks good. So why are you feeling these exercises in your hips instead of your abs? And why is it painful?

News flash: The core and the hip flexors are connected, explains Christi Marraccini, NASM-certified personal trainer, and head coach at Tone Housein New York City. “This means a lot of our go-to core movements make it hard to work the abs without working the hip flexors as well, and vice versa,” she says. “So having strong or weak hip flexors will affect your core, one way or another.”

Chances are, if you’re feeling it in your hips, you may have poor hip mobility. Past injuries, your current workout or workouts, or even your lifestyle can affect the amount of hip mobility and flexibility you have. The issue could be connected to your quads as well, explains Marraccini. “Are your quads tight or are you quad dominant, meaning your quads tend to take over when doing leg exercises?” she asks. “Because the quads are connected to the hips as well, they affect each other, too.”

So what should you do if you’re feeling some discomfort in the hips while you’re working to chisel your middle? First, notice if your hips are firing before your core during the exercise. “If so, you’re most likely using strength from the hips to do the exercise and not relying on your core strength,” says Marraccini. “You can still perform these abs exercises, like leg lowers and toe touches, but these may not be movements that you’ll benefit from most.” Because the hips and core are connected, you will always be working the hips during abs exercises, and feeling discomfort when you’re pushing yourself or taxing a certain muscle group is normal.

However, if you’re feeling pain in the hips, avoid doing the exercise that’s causing you pain. If you’re in a group fitness class, let the instructor know and ask if there is a modification that you can do instead. Marraccini recommends keeping it simple. “It is fun to do the ‘fancy’ core exercises every now and then but it’s always great to bring it back to the basics—exercises such as planks and standing cable twists are great since they focus on engaging the core first and are less hip dependent,” she says. “Butterfly situps are also great since they help to disengage the hips slightly and recruit a bit more core strength.”

You should also incorporate mobility into your workouts; not just for your hips but your entire body, suggests Marraccini. “We are constantly in a ‘crunch’ position sitting at a desk or a computer all day, so taking the time to stretch, open up the hips shoulders, and back, and to just recover will only improve your workouts.”

And don’t just give up on abs exercises if you’re feeling uncomfortable or fatigued in the hips. “These muscles are the center of your body, where all your power and stability come from,” says Marraccini. “This is the base to grow as an athlete or just as a healthier individual.”