@markus_marthaler: Propulsion in freestyle comes from one thing only. Pushing water backward. Every part of the stroke that moves water in any other direction, downward, sideways, upward, produces effort without producing forward movement. The hand and forearm are the primary propulsive surfaces. Together they act as a paddle. A paddle generates force proportional to the area facing the direction of travel and the speed at which it moves through the water. More surface area facing backward means more propulsion. Higher hand speed means more propulsion. Surface area facing the wrong direction or moving the wrong way means wasted effort. This is why the catch matters so much. The moment the forearm becomes vertical and faces directly backward, the effective paddle area doubles compared to a hand-only pull. The same muscular effort now moves twice the surface area in the right direction. No additional fitness required. Just positioning. It is also why the pull should accelerate. Propulsive force increases with the square of hand velocity through the water. A hand moving twice as fast produces four times the force. Starting slowly at the catch and accelerating through to the finish is not just a coaching preference. It is the mechanically optimal way to apply force. Everything in freestyle technique worth working on connects back to this. Does this position move more water backward. Does this movement increase paddle speed through the water. If the answer to both is no, it is not making the swimmer faster. Technical fact: Propulsive force in freestyle is generated by drag on hand and forearm surfaces oriented perpendicular to the direction of travel. Force is proportional to surface area and the square of hand velocity. Early vertical forearm mechanics maximise effective paddle area. Pull phase acceleration maximises force output. Any deviation in surface orientation or velocity direction reduces propulsive efficiency proportionally. Move water backward. Everything else is just drag in disguise.
