1 . Crunch
Lying flat on the ground with knees bent and hands behind the head, push lower back into the ground and lift upper back off the ground and slightly forward.
2 . Vertical Leg Crunch
Lie flat on the floor with lower back pressed to the ground. Place hands behind head. Extend legs straight up, crossed at the ankles with a slight bend in the knee. Contract abdominal muscles by lifting torso toward knees. Make sure to keep chin off your chest with each contraction. Exhale as you contract upward; inhale as you return to the starting position.
3 . V Ups
Lie faceup with legs and arms extended. Keeping knees and elbows locked, simultaneously raise upper body and lower body while trying to touch fingers to toes.
4 . Raised Knee In
Lie on back, arms along sides, palms down and just under lower back and butt. Press the small of your back against the floor and extend legs outward, with heels about 3 inches above the floor. Keeping lower back against the floor, lift left knee toward chest. Your right leg should remain hovering above the floor. Hold, then straighten left leg to the starting position and repeat with right leg.
5 . Reverse Crunch
Lie flat on the floor with lower back pressed to the ground. Place hands behind head or extend out alongside body. Crossing legs at ankles, lift feet up. Pull lower back off the floor as you contract abs. Reach legs toward the ceiling with each contraction.
6 . Flutter Kicks
Lie faceup with legs extended, toes pointed, and hands tucked underneath glutes to support lower back. Lift both legs off the floor a few inches and alternately kick legs up and down.
7 . Side Plank
Lie on side with lower arm bent at the elbow. Place lower elbow beneath shoulder and place upper hand on hip. Align ankles, hips, shoulders, and head. Push body toward the ceiling, balancing on the edge of your bottom shoe with one foot directly over the other.
8 . Lying Side Crunch
Lie on on your side with knees bent at a right angle and twisted to the left. Curl upper body, lifting shoulders off the floor a few inches. Pause at the top of the contraction and slowly lower back down. Switch sides and repeat.
9 . Oblique V Up
Lie on side, arms folded across chest. Keeping legs together, lift them off the floor as you raise top elbow toward hip. Place opposite hand on the floor if you need extra stability.
10 . Russian Twist
Sit on the floor, knees bent and feet flat. Hold arms straight out in front of chest, with palms facing down. Lean back so that your torso is at a 45-degree angle to the floor. Twist to the right as far as you can, pause, then reverse movement and twist to the left.