Conventional swimming strokes are freestyle, breaststroke, backstroke and butterfly; Wild swimming also includes: side swimming, diving, dog planing, backstroke, treading water and so on. And butterfly stroke is the most fitness; Because butterfly swimming needs the waist and abdomen to drive the thigh and calf to do dolphin-like swing, and both hands are inserted forward to paddle along the S route at the same time, which can exercise the muscles, bones and joints of the arms, waist and abdomen, legs and the whole body, accelerate the blood circulation of the whole body, and the exercise amount will be great and the exercise efficiency will be higher.