A push-up (or press-up) is a common calisthenics exercise performed in a prone position by raising and lowering the body using the arms. Push-ups exercise the pectoral muscles, triceps, and anterior deltoids, with ancillary benefits to the rest of the deltoids, serratus anterior, coracobrachialis and the midsection as a whole. Push-ups are a basic exercise used in civilian athletic training or physical education and commonly in military physical training. They are also a common form of punishment used in the military, school sport, or in some martial arts dojos.
In the past this movement was called a floor dip
The American English term push-up was first used between 1905 and 1910 while the British press-up was first recorded in 1928
In the "full push-up", the back and legs are straight and off the floor. There are several variations besides the common push-up. These include bringing the thumbs and index fingers of both hands together (a "diamond pushup") as well as having the elbows pointed towards the knees. These variations are intended to put greater emphasis on the triceps or shoulder, rather than the chest muscles. When both hands are unbalanced or on uneven surfaces, this exercise works the body core. Raising the feet or hands onto elevated surfaces during the exercise emphasize the upper (minor) and lower (major) pectorals, respectively. Raising the hands with the aid of push-up bars or a dumbbell allows for greater ROM (range of motion) providing further stress for the muscles. In most push-up variations a person will be lifting about 65% of his or her body weight.
Source: Wikipedia
