If you’re like most women, you notice that the backs of your arms get a little looser every year. Personal trainer Amy Carillo suggests trying the triceps seesaw on a stability ball. Just watch your upper arms firm up!

What It Works

“It might sound complicated,” says Carillo, who’s certified by the Aerobics and Fitness Association of America, “but it’s really one of those exercises that gives you the most bang for your buck.” She says that this exercise not only shapes and tones the back of the arm but also gets your abdominals and legs into the act.

How It Works

You’ll be working the triceps, which is made up of three “heads”: the lateral, medial, and long. Because you’re also stabilizing your body on the ball, you’ll activate leg muscles (calves, quads, and glutes) and your entire core, or abs area.

Work It

Starting Position. Get yourself into a push-up position on a medium-size stability ball so that your quads are directly on the ball. Your legs are straight, and your toes pointed. Your hands should be directly under your shoulders—with your fingers pointing forward and elbows straight—supporting the weight of your upper body. Pull your navel in and up toward your spine. Your body should be in a straight line from the top of your head to the tips of your toes.

Movement. Rolling forward on the ball, inhale as you bend your elbows and lower your chin to a spot about two inches above the floor. Your knees should now be directly on top of the ball so that your body is in a seesaw position. Hold for a count of two seconds, and then exhale and press your body back to the starting position.

Work It Easier

To make this movement easier, roll forward on the ball only a very short way, so that your elbows don’t bend too much and your chin is four to six inches from the floor.

Work It Harder

This is a challenging movement to begin with, Carillo says. But if you’re looking for an added pump, place a light dumbbell between your feet and hold the count for four seconds, instead of two, before returning to the starting position.

When to Work It

Carillo suggests incorporating this movement into your triceps routine three times per week with three sets of ten reps. Rest for two minutes between sets.

Work It Better

In order to get this movement right, body position is essential. Keep these points in mind with this exercise:

• Hold your body in a straight line as you perform the seesaw movement.
• Always keep your navel pulled up and in toward your spine.
• Maintain tight glutes (squeezed and contracted) through the entire movement.