“You’re going to break your back benching like that”, “look at her back” and “why is she doing that?” and so on, all the comments that every powerlifter rolls their eyes at when they post a video on social media. So I guess I’ll get straight to the point, why do powerlifters bench with an arched back?
- Decrease the range of motion (ROM)
In competitions, you get a ‘start’ command which is when you should start the bench press movement. Once the bar is stationary and paused on your chest, you get given a ‘press’ command where you finish the movement and press the bar up from your chest. A large arch and wide grip significantly reduces the distance that the bar has to move to the chest, making it easier to press a heavier load. This is the same as the fact that you can squat more weight if you do a quarter squat compared a squat that is below parallel.
- Allows you to recruit more leg drive
The powerlifting-style bench press is not just a chest exercise but a whole body exercise. An arched back allows you to use more leg drive. When benching in the powerlifting style, your bum is not sat on the bench but merely resting on the bench and your feet are flat on the floor. This means that the movement is coming from drive of your feet and legs pushing against the floor, not just from isolating the chest muscle. Why do you want to do this?! Which is stronger, your whole body or your chest? This in turn again allows you to shift a heavier load.
- Potentially safer for your shoulders
As discussed in point 1, an arched back decreases the ROM of the bench press movement which allows for a closer touch point to the shoulders. A closer touch point means that there is less shoulder rotation. If there is too much shoulder rotation during the movement, it may lead to shoulder impingement.
I think the key point to remember is that a powerlifting style bench press is a whole body exercise, whereas a bodybuilding style bench press is a chest isolating exercise. They are performed differently as they are essentially different exercises which share a name.