How to Build Stronger Freestyle Kick Mechanics

Courtesy of Gary Hall Sr., 10-time World Record Holder, 3-time Olympian, 1976 Olympic Games US Flagbearer and The Race Club co-founder.

To build a better freestyle or flutter kick, one must first understand where the propulsive power of the kick is derived and how to balance the two opposing forces of propulsion and frontal drag, in order to maximize the kicking speed.

The Battle Between Frontal Drag Forces And Propulsive Forces

As with the pulling motion, there is a battle going on between frontal drag forces and propulsive forces. Unlike the arms, however, where some propulsion is attained from the forearm, wrist and hand, all of the propulsion from the kick is derived from the foot. In fact, all of the propulsion from the kick comes from the down kick of the foot, not the up kick.

An Extremely Flexible Ankle

In order to create a propulsive force in the water, the foot, like the hand, must be moving backward relative to the water. There is really only one point in the kicking cycle where that happens and that is at the beginning of the down kick. For a very brief time, perhaps a tenth of a second or so, with the contraction of the strong quadriceps and hip flexors, enabled by an extremely flexible ankle, the foot moves backward in the water, creating the propulsive force. The amount of the force depends on the surface area pushing backward and speed or acceleration of that area. Both of those depend on strong leg muscles and great ankle flexibility.

Increasing The Plantar Flexibility Of The Ankle

There are only two ways I can think of to increase the surface area of the foot pushing backward on the down kick, short of growing a bigger foot. One is by bending the knee more in preparation for the down kick. The other is by increasing the plantar flexibility of the ankle, enabling the foot to start from a different position on the down kick. Bending the knee too much is a bad choice, as the frontal drag forces will more than compensate for the increased propulsion. What is the right amount of knee bend? You will see exactly in some of our upcoming Race Club webisodes. So that really leaves us with one good option for improving the kick, improve ankle flexibility.

Here’s some exercises to increase ankle flexibility:

Understand the Propulsive Phase of the kick:

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Gary Hall, Sr., Technical Director and Head Coach of The Race Club (courtesy of TRC)

Gary Hall, Sr., Technical Director and Head Coach of The Race Club (courtesy of TRC)

Yours in swimming,

Gary Sr. [email protected] 
<http://[email protected] <


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Coach Cal

This article lost me in the first paragraph. “all of the propulsion from the kick comes from the down kick of the foot, not the up kick.”


Agreed, I can feel the pressure on the up kick on the bottom of my foot. In that direction, the foot is shaped for propulsion.


I stand corrected. There is propulsion on both the up kick and the down kick (in freestyle, for example). What confused me was that with the up kick, the foot is never moving backward relative to the still water. The water is not still behind the swimmer, however, so that even a foot moving upward within a stream moving forward can produce propulsion. The amount of propulsion produced by the feet not only depends on the direction of the foot (up or down) but also on the vortex or stream behind the swimmer. For that reason, the velocity curves of a dolphin kick on a swimmer’s stomach are substantially different than the curves of the same swimmer on his back.… Read more »

Coach Dave

Why would the kick give any propulsion while the swimmer’s speed never goes down enough so the kick would actually be propulsive ?

This is not accurate, you cannot add speeds, you can only go as fast as the better “motor” goes.

The kick role is to counter balance the action of the arms in front not be propulsive.


You are correct in that when a swimmer reaches a certain speed, there is a point (threshold) at which the drag forces required of bending the knees to produce a kick becomes greater than the potential propulsive forces from the kick…ie the kick becomes detrimental to overall speed. This threshold speed depends on the flexibility of the ankle and potential to produce propulsion from the foot. For fast kickers, the threshold speed is faster than most swimmers can sustain for very long. For slow kickers, the threshold speed may be pretty slow. I have seen triathletes that do not move forward with the kick at all, so using the legs for them is not a good idea, as it will… Read more »


Lets stir some debate here –

Is it not commonly accepted at this point that the kick acts as a stabilizer and doesn’t create propulsive forces when swimming front crawl?

Coach Dave

Apparently not commonly accepted, even if that is pretty clear for me, and a lot of people I am working with. But The main problem is that is very difficult to demonstrate in an experience, if if it is perfectly logical and no argument against stands when getting down to it.

Thanks for your comment

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