front arm

The front crawl or forward crawl, also known as the Australian crawl or American crawl, is a swimming stroke usually regarded as the fastest of the four front primary strokes. As such, the front crawl stroke is almost universally used during a freestyle swimming competition, and hence freestyle is used metonymically for the front crawl. It is one of two long axis strokes, the other one being the backstroke. Unlike the backstroke, the breaststroke, and the butterfly stroke, the front crawl is not regulated by World Aquatics. Hence, in "freestyle" competitive swimming events, any stroke or combination of strokes is permissible. This style is sometimes referred to as the Australian crawl although this can sometimes refer to a more specific variant of front crawl.
The face-down swimming position allows for a good range of motion of the arm in the water, as compared to the backstroke, where the hands cannot be moved easily along the back of the spine. The above-water recovery of the stroke reduces drag, compared to the underwater recovery of breaststroke. The alternating arms also allow some rolling movement of the body for an easier recovery compared to, for example, butterfly. Finally, the alternating arm stroke makes for a relatively constant speed throughout the cycle.

View More On Wikipedia.org