How To Build Big Shoulders Using A Shoulder Press Machine When you begin to use a professional shoulder press machine, surprisingly enough, you are actually utilising much more than only the three general shoulder muscles to complete the lift.

The human arm muscles are actually the main movers when it comes to the shoulder press, although the main muscles in both your core and trunk tend to contract in order to balance you well when you begin to lift. So it's much more than an isolation exercise.