What is a bench press?

In one line

A bench press is an exercise in which you lie on your back on a bench, lower a barbell to your chest, and push it up until your arms are straight.

What is a bench press?
The lift behind "How much do you bench?"
At the gym, when people ask how strong you are, you often hear "How much do you bench?" It is the exercise where you lie on a bench and push a barbell up. This post explains what the bench press movement is and which muscles it uses.
In one line
Lie down and push the bar up over your chest
A bench press is an exercise where you lie on your back on a narrow bench, lower a barbell to your chest, and push it up until your arms are straight. When you hold a dumbbell in each hand instead of a barbell, it is called a 'dumbbell bench press'.
Several joints at once
The shoulders and elbows move together
As the bar comes down the elbows bend, and as it goes up the elbows straighten. Meanwhile the upper arm moves at the shoulder joint as well. Because two joints move together, the bench press is classed as a 'compound exercise'.
Muscles used ①
The chest muscle: the pectoralis major
The large muscle that spreads like a fan over the upper front of the chest is the 'pectoralis major'. Its job is to pull the upper arm toward the front of the body. In studies where people did only the bench press for several weeks, this muscle clearly grew.
Muscles used ②
The triceps on the back of the arm
The muscle on the back of the upper arm, the 'triceps', straightens the elbow. It is used as the elbows straighten while you push the bar all the way up. When researchers measured the small electrical signals muscles give off as they work, the triceps worked about as hard as the pectoralis major in the bench press.
Muscles used ③
The front of the shoulder: the deltoid
The muscle that covers the rounded part of the shoulder is the 'deltoid', and its front part also works in the bench press. Measured by those electrical signals, it worked less than the pectoralis major and the triceps. Still, in a study where people did the bench press for several weeks, the front of the shoulder grew too.
By bench angle
Incline and decline
Done on a bench tilted with the head end raised, it is an 'incline bench press'; on a bench with the head end lowered, a 'decline bench press'. The movement of lowering the bar toward the chest and pressing it up is the same; only the bench angle differs.
A competition lift
The second powerlifting lift
The bench press is one of the three lifts in 'powerlifting', a sport where people compete on how much barbell weight they can lift, and it comes after the squat. Under international rules, the lifter lowers the bar to the chest or belly, holds it still for a moment, and on the referee's signal presses it up until the elbows are straight.
A common myth
Does the bench press only build the chest?
It is known as a chest exercise, but it does not use the chest alone. In studies where people did only the bench press for several weeks, the triceps on the back of the arm and the front of the deltoid grew along with the pectoralis major. The pectoralis major did grow more than the triceps.
Summary
Push up while lying down, using chest, arms and shoulders
A bench press is an exercise where you lie on a bench, lower a barbell to your chest and push it up until your arms are straight. Not only the chest but also the triceps and the front of the shoulder work, and they grew too. Related terms: compound exercise, powerlifting, grip.