Christian Thibaudeau wrote:
1. It's not like growth in a small region can occur at rates that make visible changes within weeks... correcting a lagging area takes a lot of time.
2. The upper chest (clavicular portion of the pectoral) is probably one of the hardest muscle to bring up. if you have decent shoulders the front deltoid will take over as soon as you use an incline and if you use a flat exercise, the rest of the pec (sternal portion of the pectoral) will take over.
Incline work, can work to an extent, but rarely by itself if the upper chest is lagging behind the shoulders.
Here are some suggestions:
1. You must learn to feel and activate your upper chest. I suggest doing INCLINE squeeze presses. Here is a video that includes the squeeze press. It's the flat version, but do it on an incline (slight incline).
Note that the goal is NOT to use a lot of weight on this exercise. The goal is to SQUEEZE the dumbbells hard against each other during the push and go slow. Feel the pec cramp.
Do this exercise EVERY DAY. It doesn't cause muscle damage so don't worry, you wont overtrain the muscle. But you will learn to maximally recruit the upper chest. Really focus on squeezing with the upper chest. 3 sets of 8-10 reps at the end of every single workout. for at least 3 weeks. After that you should have a much much greater capacity to involve the upper chest maximally in other movements.
2. Use REVERSE GRIP bench press in the Smith machine (I'm not a huge Smith machine guy but for this exercise it works better). (1) use a fairly wide grip (2) start the bar in line with the collar bone (3) use a reverse grip (4) use a slight incline... (5) focus on squeezing at the top and lower the bar in 5 seconds per rep... 6-8 reps.
3. Include an upper chest day in your weak (on top of your regular chest day)... start with 3 sets of squeeze press to activate the mind-muscle connection, move on the the reverse-grip bench as mentioned for 3-4 sets. THEN do incline DB presses and go heavier. You will NOT be able to use as much weight as normal because the chest will be fatigued. That's fine, we put it 3rd to learn to integrate the upper chest in the movement. Don't focus on the squeeze, just do the exercise. 5 sets of 5. And finish by cable cross overs with the pulley set in line with the shoulders and doing the exercises keeping the arms parallel to the floor (your hands will be in front of your mouth at the peak contraction). 3 sets of 12-15.