This article is the first one in a series about freestyle stroke mistakes. The mistake this article focuses on is called Putting on the Brakes. Here's a swimmer that exhibits this flaw:
Putting on the Brakes
Putting on the brakes is a mistake in the freestyle stroke that can occur when the arm extends forward underwater during the recovery.
Normally your recovering hand enters the water in front of the head with a slight downward angle, before it sweeps forward parallel to the water surface in a straight line. Your arm simply follows behind through the hole opened in the water by the hand until your arm is completely extended.
Now it often happens that swimmers sweep their hand forward in an arc rather than a straight line. The hand is first angled down when entering the water, then is brought parallel to the water surface midway through the underwater recovery, and finally is angled up when the arm is completely extended, just before the active phase of the arm stroke starts.
As a consequence the swimmer pushes water forward at the end of the recovery, which slows him/her down.
Fixing Your Swimming Technique
This is one of the cases where swim paddles can be useful to improve one's swimming technique. The pressure of the water against the paddle will make you more aware of the angle of your hand while recovering your arm forward under water. In fact, it is more difficult to recover your hand forward with a swim paddle unless it is parallel to the water surface.
So it can be useful to swim a few lengths of freestyle with swim paddles regularly to correct to this mistake. Over time your awareness about the angle of your hand during the underwater recovery will improve and you will be able to correct this mistake.
One word of caution however, don't swim paddles too much because this can lead to swimmer's shoulder.