As a personal trainer I often advice others of how to make gains and progress with their goals in the gym - free of charge. A popular
question I often receive is to suggest a few exercises to develop the inner chest, or in other words pectoral muscles. Most individuals
starting off have little or no inner pec development and usually don't have access to any cable apparatus that advanced gyms have.
Most stick with the basics of chest training which includes bench presses and dumbbell flys which actually target the outer and upper
Well, there are several good movements for the inner pecs. If you had access to a cable crossover unit, that would be an excellent movement to develop the muscles along the sternum. The main inner-pec movement is the close-grip bench press but rather than doing it with your hands really close together (six inches or less) as you do when using the close-grip bench press for developing triceps, I suggest you use a grip with hands more like 12" to 15" apart to get the inner pecs more involved.
Another good movement for the inner pecs is the pec-dec machine, holding the pads together for several seconds until you experience an intense contraction in the pecs. For variety try supersetting the pec-dec movement with close-grip benches, again using a 12"-15" grip.
Also for variety try the pullover and press to hit the inner pecs. Lie on a bench, taking a 12"-15" grip on the bar and do a bent-arm pullover; then immediately a close-grip bench press, alternating reps of each movement until exhaustion, Try doing some sets of flys with your arms crossed over your chest, consciously tensing the inner pecs.
Lastly you may wish to try the round the world movement to hit those inner pecs. Lie on a bench holding two light dumbbells at arms length as if you were beginning a dumbbell bench press. Instead do a dumbbell pullover; but rather than bringing the bells back overhead, swing them out to the sides in a sort of/lying motion. Then bring the bells back in front of your body over your thighs until your arms are crossed and tension is on the inner pecs. From there swing the bells back to the sides and around your head until they end back up in the original position.