MUSCLES ENGAGED Abdominals The abdominal muscles (abs) provide movement and support to your core area. The deeper and closer to the spine the particular abdominal muscle is, the more effect over body posture it will have, and this often contributes significantly to a healthy back. Equipment Used Kettlebell The kettlebell is a cast-iron weight (resembling a cannonball with a handle) used to perform ballistic exercises that combine cardiovascular, strength and flexibility training. Sizes may range from 4 pounds (1.8 kg) to 175 pounds (79 kg). Exercise Instructions Step 1 Start on your back with your feet raised while holding the kettlebell above your chest with both hands. Step 2 Lift your hips up off of the ground and press both legs straight up toward the ceiling. Step 3 Lower your hips back down to the starting position and repeat.