Dumbbell Flys are a great way to
build inner chest.
Swimming will also help
build your inner chest and it's perhaps the best way to develop all layers of your chest muscles due to the amazing range of motion.
Not exact matches
What also fills out the
inner portion of the whole
chest more is using a 2 inch thick cambered bench bar, over hand grip and reverse grip to get a deeper fuller pec stretch, this has been
building my
chest better fuller more mass.
But look at it this way: if you do rotator - cuff exercises, a few years down the road you will still be able to do heavy
chest, back, shoulder and arm work, whereas those who did not strengthen their
inner shoulders will be using pansy - ass weights trying in vain to save whatever muscle they already
built.
I'm not saying if you only did this exercise, you would
build a big lump of muscle just in your
inner chest... what I'm saying is you can put focused tension on muscle fibers in a specific location or orientation even though you're NOT excluding the other fibers of that muscle.
The exercise I've got for you here targets the
inner aspect of the
chest very strongly... and with a heavy pressing movement, which is very useful for
building.