Analysis of The Push Ups

The Push Ups is a convenient and effective way to work the muscles of the upper body. Several major muscle groups are exercised with a simple motion. The push-up primarily targets the muscles of the chest, arms, and shoulders, support required from other muscles results in a wider range of muscles integrated into the exercise.
Abdominals
The rectus abdominis and transversus abdominis contract continually while performing push-ups to hold the body off the floor and keep the legs and torso aligned. The rectus abdominis spans the front of the abdomen and is the most prominent of the abdominal muscles. The transversus abdominis lies deep within the abdomen, wrapping around the entire abdominal area. Both muscles compress the abdomen, and the rectus abdominis also flexes the spine forward, although it does not execute this function when performing push-ups.
Deltoid
The anterior portion of the deltoid muscle is one of the major shoulder-joint horizontal adductors, moving your upper arms toward your chest during the upward phase of a push-up. It also helps control the speed of movement during the downward phase. The deltoid attaches to parts of the clavicle and scapula, just above the shoulder joint, on one end, and to the outside of the humerus bone on the other. Along with horizontal adduction, the anterior deltoid assists with flexion and internal rotation of the humerus within the shoulder socket.
Pectoralis major
The pectoralis major is another main horizontal adductor of the shoulder joint, so it performs the same functions as the anterior deltoid during a push-up. It also contributes to adduction, extension, flexion and internal rotation ranges of motion. The muscle is divided into clavicular and sternal parts. Both parts attach just outside the head of the humerus and run toward the center of your body. The parts then separate, with the clavicular part attaching to the inner two-thirds of the clavicle, and the sternal part to the front of the sternum and the first six ribs.
Triceps brachi
While the anterior deltoids and pectoralis major muscles work to horizontally adduct the upper arms during the upward phase of a push-up, the triceps brachii muscles, or triceps for short, are also hard at work extending the elbow joints so you can fully extend your arms. The triceps also control the speed of elbow-joint flexion during the downward phase of the exercise. The closer together you place your hands during a push-up, the harder the triceps work. The muscle is divided into three heads — the lateral head, long head and medial head. The lateral and medial heads attach to the back of the humerus bone and the long head attaches just behind the shoulder socket on one end; all three heads combine and attach to the back of your elbow on the other.
Serratus Anterior
This is located under the armpits on the sides of the chest. They are sometimes referred to as “wings,” because they give the look of a wide back and shoulders. The serratus anterior is used to pull the shoulder blade forward and around the rib cage during the pushing portion of the push-up.
Coracobrachialis
This is a narrow muscle that runs from the shoulder blade to the biceps in the upper arms. The coracobrachialis pulls the upper arm forward and against the upper body. This motion is necessary to perform a push-up. You usually cannot see the coracobrachialis, but it is important to develop it to build upper-body strength.