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. Glutes Gluteal Muscles (Glutes) are one of the strongest muscles in the body and are the connecting point between your legs and back muscles. Glutes are used in a variety of actions from moving the leg to extending and rotating the hip, as well as extending and rotating the trunk of the body. Exercise Instructions Step 1 Start in a basic plank position with your hips tucked, your glutes contracted and your back straight, while maintaining a tight bridge. Step 2 While maintaining the plank, extend one arm and perform a leg raise with the opposite leg at the same time. Step 3 Return your arm and leg to the starting position, alternate sides and repeat the action.