Today I went an did my chest workout at my gym. I realized as I was doing machine incline presses and machine flat bench presses that my arms and shoulders were getting more of a workout then my chest. I've been trying to contract the muscles in my chest, but it just doesn't seem to be working. I did standing cable crossovers just fine and felt my pecs getting a workout. Any tips for those machine presses and how to contract my chest muscles more effectively?
I have the same problem sometimes. I always find with the fly easier to activate the right muscle groups as it isnt so demanding on the shoulders as a press. For any kind of press, machine or free weight, try and keep your shoulders retracted and arch your back slightly with your chest pushed out. Its quite hard to get the form right, particularly keeping the shoulders back so practice the form with lighter weights before you go up. If you feel like your shoulders are creeping forward, at the top of the motion bring your shoulders back before you go down for the next rep.