To stretch the Pectoralis Major extend your arm and grasp a support post with your hand at a 90 degree angle to your body. Then, slowly, rotate your chest in the opposite direction of the support post. Reverse arms and stretch the other side of your Pectoralis Major.
To insure that you are stretching out the entire Pectoralis Major repeat this exercise with your hand 6 inches higher, then six inches lower.
This exercise stretches primarily the Pectoralis Major, and the Anterior Deltoid and Biceps Brachii.
Benefits of Stretching the Pectoralis Major:
Increase Pectoralis, Deltoid and Bicep flexibility
Improve circulation to your chest, shoulders and arms
Loosen shoulder/chest muscles prior to any strenuous exercises involving any aspect of your upper body
After exercises these stretches help avoid any cramping due to the tightening of these muscles during your exercise routine.