Anna Kaiser‘s known as one of the top trainers in the business—clients including Karlie Kloss, Alicia Keys, and Shakira turn to her for effective workouts, and she delivers. But you don’t have to be a celebrity to benefit from her method. Kaiser posted one of her go-to full-body exercises on Instagram, and all you need is a stability ball to try it for yourself.
They exercise is called a stability ball abs curl, and even though “abs” is right there in the name, it also targets the arms, shoulders, back, inner thighs, and glutes. It’s a mainstay move at her AKT studios in NYC.
In fact, “every client that comes into our studio is doing this exercise,” Kaiser tells SELF. And that goes for her celebrity clients, too. In particular, “Kelly Ripa loves this exercise—well, she loves to hate it.”
And it’s definitely a “love to hate” exercise. It’s tough, but effective. With your shins on a stability ball and your hands on the ground in a plank position, you bring your knees in toward your chest (rolling the ball with you), then press them back to starting position. Then, do a push-up. Here’s what it looks like:
It’s challenging, but it’s also a true compound exercise that works multiple muscle groups at once.
Your core is the main muscle group working when you’re doing this exercise, because there’s a major stability challenge involved.
“When you decrease the base of support, you’re asking more muscles to engage to perform the exercise,” explains Kaiser. In other words, because your feet aren’t on steady ground, you’re challenging your balance, so all of the stabilizing muscles in your core have to engage more to hold you steady as you pull your knees to your chest.
This works your entire core, says Kaiser, including your rectus abdominis (what you think of when you think “abs”), your obliques (the muscles on the side of your abdomen that keep you from rotating out of your plank), your lower back, and your transverse abdomis (your deepest core muscle, which is often tough to target).
It’s also great for your arms, shoulders, chest, and back.
To make sure you’re getting all of these muscles involved, during the push-up, Kaiser has clients keep their elbows at a 45-degree angle to their bodies, rather than bringing them straight out to the sides or really close into the body. “It’s right in between so you target not only your arms and chest, but you’re also engaging your back,” she says.
Your upper body’s also working while you’re bringing your knees toward your chest. To really work your arms and shoulders, “the goal is to press into the ball with your shins and try to lift your hips over your shoulders, and not just roll the ball in toward you,” says Kaiser. “It’s more challenging this way because you’re bringing more weight over your shoulders, and you’re using more core to [drive your hips up.]”
Plus, as if the upper-body benefits weren’t enough of a reason to try this exercise, “when you squeeze your inner thighs together and squeeze your glutes, it targets your lower body as well,” says Kaiser.
While this is primarily a strength exercise, it also has a bit of a cardio element. “You are really engaging every muscle in your body, which is what brings your heart rate up,” says Kaiser. One piece of equipment, one exercise, seemingly endless benefits.
Here’s how to try it for yourself:
- With your hands on the floor slightly wider than shoulder-width apart, place your
shins on a stability ball so you’re in a plank position.
- Press your shins into the ball and pull your knees to your chest,
bringing your butt up into the air.
- Press back to the starting position, then bend your elbows at a
45-degree angle to complete one push-up.
- That’s 1 rep. Do 10, then rest for 1 minute. Repeat for 3 sets