Swim coach, Freedive Instructor and Personal trainer
Propulsion is an important aspect of swimming.
The purpose is to be as efficient as possible, using muscles only when necessary and avoiding the waste of energy.
The majority of the propulsion studies in swimming promotes front crawl. If we look closely at the underwater arm movement and the motor path of the hand, we see that the underwater breastroke and the front crawl have very similar, if not identical, motions and pathways.
The article below expands on this topic.
Being streamline means having a position in the water that creates as less drag/resistance as possible.
Brent S. Rushall said :
« It is important to consider resistance in terms of swimming performance. If resistance can be minimized, then the propulsive effects of a swimmer’s efforts will be maximized. »[Rushall B. and all 1994] (Part IV – Resistive Force)
There is 3 differents kind of resistance that a swimmer as to face [M. Toussaint and Peter J. Beek, 1992]: