The pectorals consist of both upper and lower heads. The upper, or clavicular, head is responsible for flexion, adduction and rotation of the shoulder. This muscle is important for assisting the lower, or sternal, head perform a number of exercises as well. You can target the upper pectoral muscles through a variety of body-weight exercises. Body-weight exercises have the added advantage of targeting the smaller stabilizer muscles in the shoulders and arms.
The decline pushup is similar to a standard pushup, but it places additional emphasis on the upper pectorals. Perform this exercise with your feet on a bench, and your torso supported by your hands on the floor. Place your hands slightly wider than shoulder-width apart. Keeping your body straight, extend your arms until your elbows are straight. Bend your elbows until they are completely flexed, and return to the starting position. Perform as many repetitions as you can.
Perform this somewhat difficult exercise using two benches, placed parallel to each other. Place one foot on the edge of each bench, with just your toes on the edge and your ankles hanging off. Bend at the waist and grasp the front edge of each bench with your hands. Your whole body should be supported on the bench. From this position, bend at the elbows and lower your head toward the floor. Stop when your elbows are completely flexed, and return to the starting position.
Wall Press Ups
Perform this exercise in a similar fashion as decline pushups. However, instead of using a weight bench, support your feet against a wall. Pressing your feet against the wall requires additional stabilization from the legs, abdomen and erector spinae. From an extended position, bend your elbows until they are fully flexed and return to the starting position. This exercise is extremely difficult, and may take several weeks to master.
You can stretch the upper pectorals without using any added resistance. The doorway chest stretch is a simple exercise for targeting the clavicular head of the pectorals. Stand at the edge of a doorway or wall, and grasp the edge with your hand. Stand perpendicular to the wall, and keep your grasping arm at about shoulder height. Turn your body gently away from the grasping arm to stretch the upper pectoral on this side. Hold for 10 to 30 seconds and repeat on the other side.