MY SPORTS HERO'S

The human body is composed primarily of water, and thus has a very similar density. But since only roughly 70% of the body is water, it is slightly less dense than the surrounding water, which exerts a buoyant force on it. Thus, staying afloat requires only a slight propelling of water downward relative to the body, and transverse motion only a slight propelling of water in a direction opposite to the direction of intended motion, due to generally low hydrodynamic drag. This propelling is typically accomplished by cupping the hands and using them as paddles, and by kicking the legs to push water away from the body.

With practice, technique can convert a slow or average swimmer to at least a moderately fast swimmer. Since speed converts directly into distance, the same techniques that improve speed also aid one to move farther with the same effort.

The torso and the legs should be kept as much as possible parallel to the surface of the water. Dropped legs or a slanted torso dramatically increase drag.

The hand should be extended forward of the head, as much as possible. This increases the average length at the water-line, substantially increasing speed. This is an effect long used by boat designers, and unconsciously used by "naturally good swimmers."

The time spent on the side should be maximized because the torso is smaller front-to-back than side-to-side on most swimmers. This reduces the frontal cross-section, reducing drag further, and also increasing the ratio between the body's water-line-length and width. Similar improvements are possible by orienting the narrowest direction of head, hands, legs and arms into the water. The torso is by far the most critical.

The motion of the hand, arm, and leg from back to the front should be in the air as much as possible, and in the water, oriented as perfectly as possible, because the returning appendage has to move at least twice as fast as the swimmer, and in the water generates eight times the drag (drag increases with the cube of the speed) of an equal amount of torso frontal area.

The basic "catch" of the water is not nearly as critical as the above items. Most swimmers simply grab water with their hand flat, or the fingers slightly spread, and then draw it smoothly down their body.

None of the above techniques require improved strength. With strength training, the hands and feet can be extended further into the water, gaining more propulsion. For beginners, increased strength brings only small improvements if the above strategies (minimizing drag and lengthening water-line) are not optimal.

A number of swimming styles have been developed based on the implementation of some or all of these principles.

Competitive swimming is swimming with the goal to maximize performance, usually the speed of swimming. Competitive swimming became popular in the 19th century, and is an event at the Summer Olympic Games. Competitive swimming's international governing body is FINA, which includes local sub groups such as USA Swimming (USAS) and United States Masters Swimming (USMS) in the United States, Amateur Swimming Association (ASA) and Swimming Teachers Association (STA) in the United Kingdom. FINA regulates four swimming disciplines, swum over different distances.

• Freestyle- refers to "any style", and in competitive swimming places no restrictions on what action the competitors use, except during the freestyle portion of medley swimming. In practice, almost all freestyle events are swum using front crawl. Events are held at distances of 25 m, 50 m, 100 m, 200 m, 400 m, 800 m and 1500 m. Events are held in yards at distances of 50 y, 100 y, 200 y, 500 y, 1000 y, and 1650 y.
• Butterfly- events require that the swimmer's actions retain bilateral symmetry (the left side of the body has to do the same as the right). It is commonly considered the most physically challenging of the strokes. Events are held at distances of 50 m, 100 m, and 200 m. Events are also held in yards.
• Breaststroke- from which the butterfly stroke evolved, places the additional restrictions that the swimmer's hands must be pushed forward together from the breast and that the elbows must remain under the water. It is the slowest stroke in competitive swimming. Events are held at distances of 50 m, 100 m, and 200 m. This stroke, as well as butterfly requires great shoulder strength. Events are also held in yards.
• Backstroke- places no symmetry restrictions, but swimmers must lie on their back at all times except during turns to perform the stroke. Backstroke is performed, in essence, as an inversion of the crawl — competitors swing their arms back over their shoulder, alternately, and pull through under the water to provide motive power, with a flutter kick. Events are held at distances of 50 m, 100 m, and 200 m. Events are also held in yards.

In the US all distances are swum in short course yards for NCAA and high school competition, except during Olympic years in which the NCAA championships are held in the short course meters format. Short course means that each length is 25 yards or meters. There are also world championships held in the short course meters format, however, it is not as publicized as the traditional long course (50 meters per length) world championships. The Olympic Games are competed exclusively in the long course meters format. World Championships are held each year, including both the traditional long course meters format and the less popular short course meters format. World records are tabulated separately for each event in both formats; world records are not recognized for the short course yards format.