Everything anatomy, muscle motion & kinesiology about the pectoralis major.
Learning about how your muscles are working in an exercise really helps you to focus on what muscles to squeeze and contract during a specific exercises. A mind-muscle connection is one of the most vital keys to building muscle and without it, you are sacrificing a lot of muscular gains that could be otherwise made.
Additionally, learning the correct form of commonly practiced exercises can considerably help you target the muscles that you are trying to focus on as well as prevent injury.
