I do not totally agree with the oneway street of Cack and Robboe, but they DO have affected my training philosophy in important ways, which has caused me to change my judgement on certain points.
My verdict:
- it think it is NOT possible to fully isolate parts of muscles or heads....
- I DO think it is possible to EMPHASIZE part of the muscle and make improvement in that area
- HOWEVER most exercises that EMPHASIZE parts of muscles are SMALL exercises, THE OVERALL development of BIG EXERCISES (I go with Robboe and Cack here) will in MOST CASES give MORE DEVELOPMENT in that target area too.
I.e: A big exercise like Heavy weighted dips may eventually grant you more sought after "Horseshoe shape" in the triceps than a small target exercise, such as dumbell kickbacks
- I think that IF u want to bring lacking areas up to par, you should at LEAST use another BIG EXERCISE that SLIGHTLY emphasizes that area more.
SO for innerchest you do not replace barbell pressing with pec-deck (which in my opinion does involve more inner pecs, but is TOO SMALL EXERCISE!) but replace barbell presses with dumbeel presses which allow for full range of motion AND heavy weight to be used
Oh and keep the pecdeck for the end of your workout, do some sets of 10-8 resp immediately followed by push-ups or dips (real kicker)
- I do NOT think you can your muscle shape blueprint BUT i think you CAN realize it's FULL POTENTIAL which can cause you to have a peaked biceps, which you didn't have three years ago!
Bottom line: if your genetics do not allow it you will not build the innerchest, but you wont know until you really tried it!
And this knowledge may manifest itself sooner if u stick to the big exercises.