The pushup (also known as the pressup in UK, also note that it may be spelled with a space or dash before the 'u') is a calisthenic upperbody exercise that works the pectoral, deltoid, and tricep muscles, serratus anterior, coracobrachialis, as well as the midsection. It is considered the gold standard for working the chest (for bodyweight). The pushup position, called the front-leaning rest in most military units, consists of a prone position--lying face-down horizontally with the back and legs straight and functioning as one unit, supported by the arms.