Originally Posted by Coldsnap
I have really tight pecs, so i can stabilize my scapula. But during the descent my humeral head (not the humeral but where it attaches to the shoulder) immediatly starts to protrude forward as the elbows go down. So when people say shoulders back and down do they mean the humeral head should not move at all?
I think what you're getting at is some people tend to let their shoulders move up and down throughout the lift because they believe that that creates a full range of motion. The proper way to bench involves having the shoulders pressed against the bench throughout the lift, the lats engaged, and the scapulas should remain relatively stationary. The only way the shoulders would move up is if you were to allow your scapulas to rotate underneath you on the bench, which leads to an unstable surface, a longer distance to bench, and decreased power.
The easiest way I've found to ensure that your lats remain engaged(and thus, remain in proper position throughout the lift) is while I'm setting up, to specifically pull my shoulder blades together as I establish my arch and to "pull the bar apart" throughout the lift, which help me keep my lats tight and shoulders in proper position.
When people let their shoulders move freely throughout the lift, the bench press becomes more of a bench heave with less coordination and power.