Starting Strength

torso, placing the bar quite a distance down the chest from the shoulders. This position produces an obviously very long moment arm between the bar and the shoulder, as well as a humeral angle that eliminates most of the pecs’ function from the movement, reducing the muscle mass involved and the efficiency of the lift as an exercise for the whole upper body. This technique works well for powerlifters wearing a bench press shirt that does much of the work off the chest for the lifter, but for general strength training purposes, it is not useful.
     
    Chest
     
    The chest, for bench pressing purposes, is the anterior rib cage and the muscles attached to it. The main chest muscles – the pectoralis majors, or pecs – attach to the humerus at a long insertion point along the upper third of the bone. They wrap across the rib cage to a long origin along a line from the bottom of the sternum, up to the clavicle, and along the clavicle two-thirds of the way back to its distal end at the shoulder, with the muscle fibers fanning out in a broad angle. The frontal deltoids attach with the rest of the deltoid muscle at the deltoid tuberosity, a bump on the lateral aspect of the humerus, almost halfway down the shaft of the bone. The delts fan back into the shoulder and attach to the distal one-third of the clavicle in front and to the spine of the scapula in back. This wide angle of origin allows the pec and delt muscles to apply force to the humerus over a range of angles of insertion, thus permitting a range of effective elbow positions in the bench press.
    It is important to understand the relationship between the pectoralis major and anterior deltoid muscle attachments to the humerus and the angle of those attachments. Viewed from the horizontal (a cross-section of your chest perpendicular to your spine), the pec/delt attachments occur at an angle that varies with chest position. Refer to Figure 5-17 . The higher the top of the chest – the highest point on the rib cage above the bench – the steeper the angle with which the pecs and delts attach to the humerus. The steeper the angle, the better, because of the increased mechanical efficiency of the contraction caused by the steeper angle of attack on the humerus. A lever system exhibits greater efficiency as the force gets closer to being perpendicular to the moment arm. So the higher the chest position above the arms, the better the pull the pecs and delts have on the arms. This effect is in addition to the mechanical improvement that the chest-up position produces in the previously discussed bar/shoulder relationship. The short version: keep your chest up high when you bench.

    Figure 5-17. A bigger chest – whether from training or genetics – increases bench press efficiency. The increased steepness of the angle of attack of upper fibers of the pec and delt on the humerus increases the efficiency of the pull against the bone. This characteristic of levers explains one of the advantages to be obtained by increased bodyweight and is what is meant by the term “leverage.” It applies throughout the barbell exercises.

    No discussion of the bench press would be complete without an explanation of the function of the lats in the movement. The latissimus dorsi muscles get implicated in a lot of bench pressing methods, but it is necessary to look at their actual function to assess their contribution to the movement. The lats have a very broad origin on the lower back, from T7 down across the thoracolumbar fascia to the iliac crest, covering the area of the entire lower back. This broad origin turns into a large flat muscle belly that inserts by means of a thick, flat tendon on the anterior medial side of the humerus, parallel to the pec tendon insertion under the armpit. The action of the lat is thus the opposite of the pec’s action – the lat pulls the humerus back while the pec pulls it forward. That’s why chin-ups train the lats, and bench presses train the pecs.
    But if this is the case, what function could the lats possibly have in the bench press? They can’t make the bar go forward (up), because when they contract, they pull it backward (down). A case could be made for a large lat muscle belly providing a rebound surface for the tricep as it approaches the bottom. But it is more logical that the contracted lat provides further reinforcement for the chest-up position, since a contracted lat would pull the lower back toward the shoulder, if permitted to do