This is a basic guide to a swim cool down, and a few reasons why you should do it. 

The idea for a cool-down in swimming is to actively start the recovery process, by gradually reducing muscle temperature and starting to remove lactic acid away from the muscle. When we exercise there is an increase in the ph balance of the muscle this leads to that burning sensation that we start to feel as intensity or duration increases.

A cool down should last at least 10% of the distance that you have swum during your set. 

      As part of the cool down it is advisable to reduce intensity of the stroke which has been predominantly used. Placing an emphasis on good form and technique. Backstroke is a particularly good option as it requires the joint to be rotated in the opposite direction, this stretches out the muscles that have been used during front crawl and helps prevent tension from building in the Pecs and Lats. 

    Combined with some static stretching after leaving the pool it can improve posture and prevent us from becoming too round shouldered. 

Happy swimming!