The bone in the middle of the anterior chest is the human sternum. The only joint on the sternum that can make a sound is called the stalk joint, which is a joint made up of the sternal stem of the sternum and the body of the sternum. The only joint on the sternum is connected by a lot of fibrocartilage on the outside, which protects the stalk joint to prevent the stalk joint from moving more than the range, but some people often overwork, overactivity or strength training will lead to the relaxation of the fibrocartilage on the outside of the stalk joint, which will lead to the increase of the range of movement of the stalk joint when the shape of the chest profile changes or when doing When there is a change in the shape of the chest contour or when doing chest lifts, the external force on the stifle joint will cause the joint to move beyond its range, thus causing the bones to rattle. This is a relatively normal phenomenon, and people who experience this phenomenon usually do not experience localized pain. If there is localized pain and a rattling sound in the middle of the sternum, injury or inflammation of the stalk joint should be considered.