Try this simple ab move for a toned core

Youve probably spent your whole life doing situps, so youll be forgiven if you think every single ab exercise performed on your back will turn into some type of crunch.

Trainer Charlee Atkins, C.S.C.S., says that she surprises clients when she teaches them ab circles, a move that has a similar starting position to situps. That beginning point, however, is where the commonalities end - and that difference makes the exercise a big hit.

"My clients love this exercise," Atkins says. "They often exclaim, 'How have I never done these before?'"

The key to the move is the hollow body position, a core-crushing technique popular with gymnasts. Once you add motion from your upper body to the equation, you have a well-balanced, ab-shredding exercise.

"The continuous circle hits the upper abs while the rest of the core stabilizes the lumbar spine," says Atkins. "It’s a sneak attack on every abdominal: upper, lower, transverse, and obliques."To perform the move, you don't need any equipment. If you want a soft surface to rest your back, though, check out this self-rolling yoga mat.

Lay flat on ground, legs extended.
Put your hands behind head, keeping your elbows open.
Start to take your upper body through a circle, keeping one shoulder blade on the mat at all times.
Move slowly in one direction for 30 seconds, and then reverse direction for another 30 seconds.

The move is simple, and your tailbone isn't at risk of being scraped on the ground like it is during reps of crunches or situps. Atkins does have one important note before you get circling: mind the tempo.

"Don’t race through these," she says. "Try to go as slow and controlled as possible."

Add ab circles to your routine with 3 sets of two 30-second rotation periods.