powerful leg muscles to be used effectively for propulsion through water. The value of fins as an active aid in the teaching, learning and practice of swimming has long been recognised. In the US, as early as 1947, they were used experimentally to build the confidence of reluctant beginners in swimming, while a 1950 YMCA lifesaving and water safety manual reminded swimming instructors how "flippers can be used to great advantage for treading water, surface diving, towing, underwater searching and supporting a tired swimmer". In 1967, research was conducted on fin use in teaching the crawl stroke. During the 1970s, the so-called "flipper-float" method came into vogue in Europe with the aim of helping beginners learn to swim faster and more safely, Hand paddles are used to increase resistance during arm movements, with the goal of improving technique and power. Finger paddles have a similar effect to handle paddles however due to their smaller size create less resistance. They also help with improving a swimmers 'catch' in the water. Snorkels are used to help improve and maintain a good head position in the water. They may also be used by some during physical therapy. Pool noodles are used to keep the user afloat during the time in the water. Safety fencing and equipment is mandatory at public pools and a zoning requirement at most residential pools in the United States. Swimming Parachutes are used in competitive training, adding an element of resistance in the water helping athletes to increase power in the strokes central movements. Inflatable armbands are swimming aids designed to provide buoyancy for the swimmer which helps the wearer to float. See also Aquatic ape hypothesis Aquatic locomotion List of swimmers List of water sports Microswimmer Mixed bathing Resistance swimming Stunt swimming Swimhiking Swimming machine Total Immersion Winter swimming References Bibliography Maniscalco F., Il nuoto nel mondo greco romano, Naples 1993. Mehl H., Antike Schwimmkunst, Munchen 1927. Schuster G., Smits W. & Ullal J., Thinkers of the Jungle. Tandem Verlag 2008. svin External links Swimmingstrokes.info, Overview of 150 historical and less known swimming-strokes Swimming