Dumbbell flies are an excellent exercise for adding size and shape to the chest. It also helps to strengthen the costal muscles, which has the effect of pulling out the sternum and helping treat the Pectus Excavatum condition.
Grasp two dumbbells. Lie supine on bench. Support dumbbells above chest with arms fixed in slightly bent position. Internally rotate shoulders so elbows point out to sides.
Lower dumbbells to sides until chest muscles are stretched with elbows fixed in slightly bent position. Bring dumbbells together in hugging motion until dumbbells are nearly together. Repeat.
Keep shoulders internally rotated so elbows point downward at bottom position and outward at top position.
Pectoralis Major, Sternal
Pectoralis Major, Clavicular
Biceps Brachii, Short Head