Plot twist: leg lifts can work your hips more than your abs, which is why back pain is a common side effect of the move.
"It's important to understand when you do leg raises, the first 90 degrees are primarily activating the hip flexors, not the abs," NASM-certified personal trainer Kim Lyons says. While leg lifts can tone abs, Lyons says that hip flexors reap most of the benefits. And since hip flexors are connected to thigh bones below the spinal column, low-back pain can be triggered.
According to Lyons, feeling a snapping sensation or hearing a popping sound at your hip joint as you raise and lower your legs can be an uncomfortable outcome of leg lifts, too.
Besides consulting with your doctor regarding the pain you're experiencing, Lyons' biggest suggestion is to consider a different ab-toning move, as she doesn't recommend the exercise for anyone with back pain.
"There are many exercises that work the core more effectively without working the hip flexors as a primary mover," she says. Her two examples: planks with alternating leg lifts to the back and bird dogs.
If leg lifts are your goal, there are several healthier options, including single-leg or bent-knee versions, that Lyons can walk you through — both are equally effective and should be progressed or regressed as needed.
- Start on your back with your knees bent and feet on the floor, as if you were going to do a crunch.
- Contract your abs to press your spine into the mat firmly.
- Raise one leg to the 90-degree angle.
- Slowly lower the leg while keeping the abs contracted.
- Keep your legs together and do not allow your back to arch off the floor. Exhale on the way up, inhale on the way down.
- Do equal reps on each leg.
- Progress to bending both knees to a 45-degree angle as you do the leg lift.
- Once the bent leg movement is mastered, progress to straight leg lifts.