Swimming Anatomy

The pectoralis major (figure 4.1 on page 62) is typically divided into two heads: the clavicular (upper) head and the sternal (lower) head. The clavicular portion comprises the upper portion of the pectoralis major and arises from the anterior surface of the inner half of the clavicle. The sternal portion forms the lower portion and arises from the anterior surface of the sternum and the cartilage of the first six ribs. The upper and lower portions join and cross the shoulder joint, attaching to the humerus. As the pectoralis major contracts and pulls on the humerus, the following movements take place at the shoulder joint: flexion, extension, adduction, and internal rotation. Flexion involves bringing the arm from the side of the body forward. Extension, the reverse of flexion, involves returning the arm to the side from a flexed position. Adduction involves bringing the arm toward the midline of the body when it has been raised to the side; this movement can be either horizontal or vertical in nature. Internal rotation involves rotating the hand across the body so that the palm is resting on the abdomen. For an in-depth description of the pectoralis minor and serratus anterior, refer to the introduction to chapter 3. For this chapter it is best to think of their role in helping to stabilize the shoulder blade and in turn the shoulder joint as the pectoralis major acts on the humerus. A number of other muscles are also activated during the exercises described in this chapter. The anterior deltoid often functions to assist the pectoralis major with shoulder flexion. The latissimus dorsi assists with shoulder extension, and the triceps brachii functions to extend the elbow joint during the many pressing exercises that target the pectoralis major.

As previously mentioned, the pectoralis major is one of two primary force generators acting to propel a swimmer through the water. During freestyle and butterfly, as the hand first enters into the water and the body is in an elongated position, the pectoralis major initiates the pulling phase of both strokes. At this time the upper portion of the pectoralis major is a key contributor to the movement. As the hand moves toward its anchor point, the lower portion along with the latissimus dorsi joins in to assist in propelling the swimmer through the water. As the hand passes below the shoulder joint, the contribution of the upper portion of the pectoralis major decreases and the lower portion takes over the primary responsibility for completing the propulsive phase. As in butterfly and freestyle, during breaststroke the upper portion of the pectoralis major is important in initiating the propulsive phase of the stroke, beginning with an outward sweep of the hands. As the hands transition into the lateral sweeping motion, the pectoralis major continues as a contributor, functioning both to adduct and to rotate the shoulder joint internally. The pectoralis major is active during the shift from the propulsive phase to the recovery phase as the hands are brought together at the midline of the body. During backstroke the contribution of the pectoralis major during the initial portion of the pull depends on the swimmer’s technique. Those with an initial deep catch depend less on the pectoralis major and rely more on the latissimus dorsi for force generation. Those who have a shallower catch initially have a greater contribution from the pectoralis major. In both instances the initial contribution comes from the upper portion of the pectoralis major. As the swimmer progresses through the pulling motion, the lower portion takes over primary responsibility for the remainder of the pulling phase.

Figure 4.1 Chest muscles.

An important consideration when designing a dryland program and choosing exercises from this chapter is that the pectoralis major is usually not an area of relative weakness in swimmers because the swimming motion activates it to a large degree. Therefore, although using exercises that target the muscles in the chest is important, keep in mind that one of the key goals of a dryland program is to address muscle imbalances, not accentuate them. To avoid overemphasizing the chest, use a 2:1 ratio of pulling exercises that emphasize the latissimus dorsi to pushing exercises that emphasize the pectoralis major.

Push-Up

Execution

1. Position your hands on the floor at shoulder level and slightly wider than shoulder-width apart. Support your lower body on your toes.

2. Holding your body in a straight line from your ankles to the top of your head, push your upper body upward until the elbows are almost locked.

3. Lower your body until your chest is 1 inch (2.5 cm) off the ground.

Muscles Involved

Primary:Pectoralis major, triceps brachii

Secondary:Anterior deltoid

Swimming Focus