The dumbbell, a type of free weight, is a piece of equipment used in weight training. It is usually used individually or in pairs, with one in each hand. History The forerunner of the dumbbell, halteres, were used in ancient Greece as lifting weights and also as weights in the ancient Greek version of the long jump. A kind of dumbbell was also used in India for more than a millennium, shaped like a club – so it was named Indian club. The design of the "Nal", as the equipment was referred to, can be seen as a halfway point between a barbell and a dumbbell. It was generally used in pairs, in workouts by wrestlers, bodybuilders, sports players, and others wishing to increase strength and muscle size. Etymology The term "dumbbell" or "dumb bell" originated in late Stuart England. In 1711 the poet Joseph Addison mentioned exercising with a "dumb bell" in an essay published in The Spectator. Although Addison elsewhere in the same publication describes having used equipment similar to the modern understanding of dumbbells, according to sport historian Jan Todd, the form of the first dumbbells remains unclear. The Oxford English Dictionary describes "apparatus similar to that used to ring a church bell, but without the bell, so noiseless or ‘dumb’", implying the action of pulling a bell rope to practice English bellringing. Types By the early 17th century, the familiar shape of the dumbbell, with two equal weights attached to a handle, had appeared. There are currently three main types of dumbbell: Fixed-weight dumbbells are weights created in a dumbbell shape. Inexpensive varieties consist of cast iron, sometimes coated with rubber or neoprene for comfort, and even cheaper versions consist of a rigid plastic shell that is filled with concrete. Adjustable dumbbells consist of a metal bar whose centre portion is often engraved with a crosshatch pattern (knurling) to improve grip. Weight plates are slid onto the outer portions of the dumbbell and secured with clips or collars. Shown to the right is a "spinlock" dumbbell, whose ends are threaded to accept large nuts as collars. Alternatively, a dumbbell may have smooth ends with plates being secured by a sprung collar. Plate-loaded (adjustable) dumbbells (a.k.a. loadable dumbbells) Spin-lock Spring collar clips Compression ring collar Ironmaster quick-lock "Selectorized" (adjustable) dumbbells are adjustable dumbbells whose number of plates (i.e. weight) can be easily changed when resting in the