Which is the role of the chest in push-ups?

Question

As simple as it may be, I find it so difficult to understand which is the chest role in a push-up (and so I don't have the proper mind-muscle connection on how activate my chest).

Chest, as said here, performs the horizontal adduction, as shown in the following picture. When the chest is gradually shortened, point A (centre of bicep) moves toward the point B (centre of chest).

Well, what does this movement have to do with push-ups?

What I see in the push-up movement pattern seems to me just a forearm extension performed by the triceps. The distance between the centre of bicep and the centre of chest seems to me about the same in the starting and ending position. I don't see any significant shortening of this distance during the execution. So, by the common pictures that show push-ups, it seems to me it's a pure triceps, exercise. But it's known it's not... so which is the role of the chest?

To make a comparison, I may easily see the role of the chest in dumbbell bench press. In this case, as shown in the following picture, the distance between the centre of bicep and the centre of chest is shortened as the dumbbells are lifted, since they are brought close together.

But in a push-up the hands position is fixed... we can't do such a triangular movement that activates the chest.... Where is my mistake?

Answer 1

Imagine the pushup like a bench press, where you do NOT bump the weights together at the top. Think of it more like a bench press with a bar, if you will. So you don't get the triangular motions, because your hands are always a fixed width apart.

It looks like you've more or less correctly pointed out that the pectoral muscles are involved in adduction, meaning it pretty much serves to pull your bicep closer to your chest.

To see how this factors into the pushup:

• get into a pushup position with your hands shoulder-width apart
• lie all the way down on your stomach with your hands still planted in their position, keeping the elbow tucked close to your sides
• note how your biceps are pretty much behind you at this point
• do a pushup into full extension of the elbow
• note how your bicep is now significantly closer to your chest, and it's right there in your field of view

To see what would happen if you didn't engage your chest, do the following:

• get into a pushup position with your hands shoulder-width apart
• lie all the way down on your stomach with your hands still planted in their position
• engage your triceps, and triceps only
• you should find yourself just sliding forward on the floor

You used the following image to illustrate how it's not apparent that any adduction is being done:

I agree that it may not be as easily seen here, because the depicted athlete is using a very wide hand position. But we can in fact clearly see that the distance between his bicep and chest is being shortened even in this position, so there is some adduction going on, in addition to just extension of the elbow.