By Stefani Jackenthal and Pam Mazzuca

Guess what? A study done at the Biomechanics Lab at San Diego State University found that crunches on a ball rank high for strengthening and toning the rectus abdominis.

WEIGHTED BALL CRUNCH

Target Muscle: rectus abdominis

Set Up: Lie on stability ball holding a medicine ball or dumbbell with your arms above your head and close to your ears [A].

Action: Contract your abs and exhale while moving into a sit-up position, keeping the weight above your head [B]. Inhale while returning to the start position and repeat.

TRY OUR AT-HOME MODIFICATION!

Set Up: Lie on your back with your knees bent and feet flat on the floor, hip-width apart and extend your arms above your head (with or without a weight).

Action: Exhale while slowly lifting your shoulders off the floor. Inhale while returning to the start position and repeat.

Do three sets of 15 reps.

Photos: Stewart Volland, Hair and Makeup: Nancy Jambazian, Stylist: Julia Perry, Model: Jelena Abbou, Clothing: Bebe