Sit on the floor while holding a medicine ball (or dumbbell) in both hands with shoulders relaxed, elbows bent, and arms pulled close to the sides of the body. Place your knees and feet about hip-width apart, heels on the floor, knees bent and back straight. Pull your abs in tight and with a straight back, lean back from the hips until you feel your abs engage (pictured).
INHALE: Keeping heels on the floor, abs engaged, and arms close to your body, twist from the waist to the left side. EXHALE: Twist back to the center (starting position). INHALE: Twist to the opposite (right) side. EXHALE: Return to the starting position to complete one rep.
Keep your abs pulled in, shoulders relaxed, and feet down at all times. Focus on twisting from the waist, allowing your upper torso and arms to turn with you. Keep your back long and flat at all times.
Make it easier: Don't lean back as far. Use a lighter weight or no weight. Limit your range of motion.
Make it harder: Lean back and/or twist further. Lift one foot off the floor to increase the intensity and balance challenge.
Muscles Worked: Abs, Obliques