In martial arts, a waster is a practice weapon, usually a sword, and usually made out of wood, though nylon (plastic) wasters are also available. Nylon is safer than wood, due to it having an adequate amount of flex for thrusts to be generally safe, unlike wooden wasters. Even a steel feder has more flex than most wooden wasters. The use of wood or nylon instead of metal provides an economic option for initial weapons training and sparring, at some loss of genuine experience. A weighted waster may be used for a sort of strength training, theoretically making the movements of using an actual sword comparatively easier and quicker, though modern sports science shows that an athlete would most optimally train with an implement which is closest to the same weight, balance, and shape of the tool they will be using. Wasters as wooden practice weapons have been found in a variety of cultures over a number of centuries, including ancient China, Ireland, Iran, Scotland, Rome, Egypt, medieval and renaissance Europe, Japan, and into the modern era in Europe and the United States. Over the course of time, wasters took a variety of forms not necessarily influenced by chronological succession, ranging from simple sticks to clip-point dowels with leather basket hilts to careful replicas of real swords.