In swimming, effective propulsive movements are SLOW to FAST.
In every stroke you reach long, feel the water, catch and then accelerate through the pull to the recovery.
A powerful stroke starts with an effective feel on the entry and then a strong catch. Once you have got that strong catch, it’s the acceleration through the stroke which makes all the difference.
A big mistake which amateur swimmers too often make is they pull through the water before they have reached long and ‘caught’ the water. Missing this step causes bubbles on the hand as the swimmer pulls through. This makes the stroke ineffective as the swimmer is pulling through air and not able to accelerate by holding the water with their catch.
During the ‘catch’ phase of the stroke (between the hand entering and the pull through) the main objective is to reach long to reduce drag, and to allow the air bubbles to leave the hand and forearm. Once they have left, the swimmer can begin the pull through with maximum effectiveness. The difference between pulling through without bubbles on the hand compared to pulling through with bubbles is many seconds difference.
If you can master the slow to fast movement with the arms and combine this with a ‘no bubbles’ approach to pulling through, you can drastically improve your swimming. It’s worth practicing the two disciplines until you get them right. It sure beats training harder and may allow you to improve your times with less effort.