Nature of Specific Basic Exercises to be Used in Posture Control and Improvement. Regardless of the type of activity being done, there are certain posture characteristics to which one must adhere if good posture is to be maintained. These characteristics involve {1) a retraction of the lower abdomen, (2) elevation of the chest, and (3) a control of the pelvic tilt.* There are other important factors in posture control as indicated in the accompanying pages (see Illustrations X and XIII), yet the three factors just mentioned are of the greatest importance. , To master these three factors one must develop postural skill in the muscles controlling the chest, abdomen, and pelvis. It is well to begin with simple exercises which involve (1) voluntary retraction of the lower abdomen, !2) voluntary rounding forward of the upper abdomen, (3) voluntary elevation of the chest, and (4) voluntary reduction of the pelvic tilt. One of the best exercises to use in helping the individual get the "feel" of posture control is illustrated below. The exercise is executed in the prone: position when first being taught. *These characteristics are equally applicable to one's posture while walking, sitting, lying, etc.