Muscle Group: Abdominals
Seated Leg Tucks work your whole core, both upper and lower abs. In all abdominal exercises, your rib cage should contract toward the pelvis or the pelvis toward the rib cage, when doing seated leg tucks, both of these things happen.
Sit across a bench, grip the sides to stabilize yourself. Lift your legs a bit and bend your knees and lean backward at about a 45-degree angle.
Then using a scissors movement, lift your upper body toward your pelvis, rounding your back, and at the same time lift your knees up to your face. Emphasize the crunch as your rib cage and pelvis squeeze together. Now, lower your torso and knees back to the starting position.