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 Dumbbells The dumbbell, a type of free weight, is a piece of equipment used in weight training. It can be used individually or in pairs (one for each hand). Dumbbells vary in weight from 3lbs. up to 150lbs. Exercise Instructions Step 1 Start on your back with one knee bent and the other leg straight. Hold a very small hand weight or medicine ball in the hand opposite of your straightened leg. Step 2 Using your abdominal muscles, lift your leg back up at the same time that you crunch up to your shin with the arm holding the hand weight. Step 3 Lower your arm and leg back down to the starting postion and repeat.