There is also a special null type, the type of the expression null, which has no name. Because the null type has no name, it is impossible to declare a variable of the null type or to cast to the null type. The null reference is the only possible value of an expression of null type.
The military barbell press mainly works the shoulder, or deltoid, muscles. The anterior deltoid, the front head of the shoulder muscle, does much of the work. The side, or lateral, deltoid and the rear, or posterior, deltoid are also involved in the movement, although to a lesser degree than the anterior deltoid.
Strong Shoulders. The spring chest expander works the deltoids as the primary muscle for the movement. There are three primary sections to your deltoids, or shoulder muscles, anterior or front, middle and posterior or back.road Back. The basic exercise of the spring chest expander also engages the upper back muscles. The pulling action requires the upper back to engage. To get more back flexion out of this exercise, squeeze your shoulder blades toward each other as you pull the chest expander outward.