Abstract
The motions of the thorax and of the shins were recorded by a technic which gives approximately the same size waves when a given force is applied to the thorax in each of three planes. Applied to a group of men and women under 30 years of age and another group of normals over 50, the variations in form and size of the ballistocardiographic forces in three planes were recorded. During expiration and as a result of aging, the lateral systolic wave, IJ, increases in size relative to the head-foot IJ. It is concluded that the classic head-foot ballistocardiogram yields inadequate information on the force liberated in systole, particularly in older men.