Swimming 101

Freestyle Events

In the freestyle, the competitor may swim any stroke he or she wishes. The usual stroke used is the front crawl. This stroke is characterized by the alternate overhand motion of the arms.

Backstroke Events

In the backstroke, the swimmer must stay on his or her back at all times. The stroke is an alternating motion of the arms. At each turn a swimmer must touch the wall with some part of the body.
Swimmers must surface within 15 metres after the start and each turn.

Breaststroke Events

Perhaps one of the most difficult strokes to master, the breaststroke requires simultaneous movements of the arms on the same horizontal plane. The hands are pushed forward from the breast on or under the surface of the water and brought backward in the propulsive stage of the stroke simultaneously.
The kick is a simultaneous thrust of the legs called a frog or breaststroke kick. No flutter or dolphin kicking is allowed. At each turn a swimmer must touch with both hands at the same time.

Butterfly Events

The most physically demanding stroke, the butterfly features the simultaneous overhead stroke of the arms combined with the dolphin kick. The dolphin kick features both legs moving up and down together. No flutter kicking is allowed. The butterfly was born in the early 1950s due to a loophole in the breaststroke rules and became an Olympic event in Melbourne, Australia in 1965.

Individual Medley

The individual medley, commonly referred to as the I.M., features all four competitive strokes. In the I.M., a swimmer begins with the butterfly, changes to the backstroke after one-fourth of the race, then the breaststroke for another quarter and finally finishes with the freestyle.

Medley Relay

In the medley relay all four strokes are swum by four different swimmers. No swimmer may swim more than one leg of the relay, which is swum in backstroke, breaststroke, butterfly and freestyle order.

Starts and Turns

Many races are won or lost in starts and turns. In the start, the swimmer is called to the starting position by the starter who visually checks that all swimmers are still. Then, once the starter is satisfied, the race is started by either a gun or electronic tone.
Quick turns are essential to a good race. In all events the swimmer must touch the wall, but in the freestyle and backstroke the swimmer may somersault as he or she reaches the wall, touching only with the feet. In the other two competitive strokes, the swimmer must touch the wall with both hands before executing the turn.

Taken from www.swimming.ca