Certain exercises have the ability to shape and form muscles more than others. This is accomplished by building a particular area of the muscle larger which then results in the shape becoming different. A great example would be doing an exercise like concentration curls to work the peak head of the bicep. It won’t be noticeable in a straight arm flex, but when you bend the elbow and flex your arm the bicep will start to look more like a ripe piece of fruit that sticks up nicely.
The decline bench press has that same ability to affect the shape of your chest. While a regular bench press can help with the overall size of your chest, it does very little to change the shape of your chest; not so with the decline bench press.
The decline bench press is usually performed at a 30 degree angle downward. This change in angle means you press upwards at a slightly different angle that uses less front deltoid and more of the lower portion of the pectoralis major as well as the pectoralis minor. The lower portion of the chest can actually become very thick and develop a flatter line across the bottom of the muscle with sufficient work. This exercise can also really work the inner portion of the chest when done with dumbbells.
On the flip side when more work is done to the middle and upper chest there can be more of a rounding of the chest. In some cases people are seen having flabby lower and outer pecs that earn them unfavorable nicknames.
While the flat bench is great for building size and incline presses help fill in the top section of your chest, the decline bench press is the primary chest shaper. Developing the lower and inner portion of the pectoralis muscle makes the muscles wider, flatter, and thicker. This is very apparent when you wear a shirt because your chest will sit lower on your rib cage and create a more prominent display like slabs of meat.
Those who focus solely on the middle of the muscle belly can create more of a rounded muscle. While that is large at also matches more of the appearance of the female chest which usually is not the goal of most male lifters.
In Your Workout
When doing the decline bench press in your routine I recommend a few variations. You should switch between barbell and dumbbell variations every few workouts. While you can use more weight with the barbell, the range of motion is superior with dumbbell and will allow a greater contraction of the muscle. You use both in alternating workouts to gain maximum benefit.
When using a barbell make sure to vary your hand grip. You might notice that with a narrower grip you will feel a much greater contraction in the inner portion of the chest. Personally for me wide grip presses do very little (due to the length of my arms) but people have different builds and some might gain a benefit with a slightly wider grip. Make sure to experiment and see what feels best with your body.
The decline bench press is a great exercise for shaping and building your chest and should be included in the rotation of exercises you use for your chest at the very minimum. As great as the flat bench press is, you need to use variety to properly hit all of the angles for a complete chest.