In bodybuilding speak, the “inner chest” refers to the fibers of pectoralis major that attach to the sternum. Specifically, those interested in building their inner chest are likely most concerned with the proximal or most central portions of those fibers.  Anyone who performs the hex press properly will tell you they feel a strong contraction of this portion of the pectoralis major. Although no studies have directly tested the hex press, let alone measured its long-term effects on chest muscle thickness, there is a case to be made for its use as an inner-chest builder.  Narrow-grip pressing tends to show lower muscular activity of the sternal part of pectoralis major compared to traditional or wide-grip pressing. (18) Although the arm path of the hex press resembles a narrow-grip or close-grip press, hex pressing involves the additional task of keeping the dumbbells squeezed together. Therefore, it’s safe to assume the “squeeze” enhances sternal pectoralis major contraction, a feat lifters may be unable to accomplish during the traditional bench press. (19)