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 disciplines.
An extremely difficult variation is to perform a push-up using only hands, without resting the feet on the floor, i.e. starting from and returning to the planche position. These are known as “planche push-ups”. To do this variation, the body’s center of gravity must be kept over the hands while performing the push-up by leaning forward while the legs are elevated in the air, which requires great strength and a high level of balance. The entire body weight is lifted in this variation.
Another variation is to perform pushups on the knuckles of the fist, rather than with palms of the hands on the floor. This method is also commonly used in martial arts, such as Karate and Tae Kwon Do, and may be used in boxing training while wearing boxing gloves.
The intent, in addition to building strength and conditioning, is to toughen the knuckles, wrist, and forearm in the punching position. This variation also reduces the amount of strain in the wrist, compared to the typical “palms on floor” approach, and so it is sometimes used by those with wrist injuries. Such practitioners will usually perform their knuckle pushups on a padded floor or a rolled-up towel, unlike martial artists, who may do bare-knuckle pushups on hard floors.