Which are better for the goal of building chest mass: incline, decline or flat chest exercises?
This is a very popular question amongst the bodybuilding community. If the goal were anything but isolation (chest mass), I would recommend pushing patterns in every possible plane. However, because your goal is to maximize recruitment for the isolated goal of chest hypertrophy (muscle growth), I have collected some research that will help you to explore that objective.
- Research employing electromyographic analysis concluded that 30 degrees above the horizontal plane of the shoulder joint to 15 degrees below are optimal angles for chest recruitment.
- Above 30 degrees, the anterior deltoid and portions of the middle deltoid became the predominate players.
- Surprising to some, both incline and decline presses activate the upper pec muscles equally. The lower pecs, however, are activated to a greater extent on declines, which increases motor unit activation overall.
- If one angle were picked for mass, the horizontal (across the body) plane wins.
To understand the research, one must explore the clavicular, sternal and costal (upper, middle, lower) portions of the pectoralis major (see Figure 1 below). When observing the pectoralis from anatomical position (as shown in Figure 1), one can clearly see the delineation between the upper, middle and lower pecs. Now ask yourself a question… When was the last time you’ve seen someone train his or her chest with their arms at their sides (anatomical position)? Probably never! Point: when your arms abduct (see Figure 2) to perform chest exercises, the relationship of the muscles relative to the axis changes; this is referred to as inversion of muscular action. In other words, when you perform a horizontal pressing motion (Figure 2), the incline, middle and lower fiber delineation is no longer so obvious; the fibers are more horizontal to one another. This explains why the incline angle above 30 degrees de-emphasizes the lower and middle portions of the chest. It also explains why the near flat to decline angle activates the upper fibers equally and how the flat bench is the optimal angle for the goal of maximal chest recruitment.
If the goal is to stimulate/isolate the chest region for maximal motor unit recruitment, thus growth, maintaining the horizontal plane (see Figure 2) will be optimal. It is also important to note that overemphasizing any one plane or angle over time can lead to pattern overload. My suggestion is to utilize the horizontal plane for your high intensity periods, but never forget that the body needs unaccustomed stimulus for continual adaptation to take place!
Figure 1: Anatomical Position
Figure 2: Horizontal Plane