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. Quadriceps The quadriceps (quads) are a group of four muscles on the front of the thigh. They allow your knee to straighten and provide stability when standing. Your quads are the most important muscle group for maintaining the ability to stand and to walk independently. Exercise Instructions Step 1 Start in a push-up position with your hands under your shoulders and your back flat. Step 2 Pull one of your legs up to the side of your hand and plant your heel into the ground. Keep your chest up and your hips down and gently try to work open your hips. Step 3 Return your leg to the starting position and repeat on the other side.