Posted on December 24th, 2009
On the TI Discussion Forum Hamilton posted this query:
On one of the swimming web sites, I found this statement: “The strength of the kick comes on the downbeat. Very little propulsion, if any, is generated with the upbeat of the kick.” I am curious to know if I should even be trying to get propulsion on the upbeat, or return stroke of the kick. Any thoughts?
Terry replied It’s true that there’s more force generated on downbeat than upbeat. But the statement you quoted is a bit too simplistic. The kick is a “system” in which all parts affect the action of all other parts. Trying to parse whether the upbeat or downbeat of the kick is more ‘important” makes no more sense than trying to assign greater importance to the upstroke or downstroke of a piston in an engine.
The whole stroke is also a system — of which the kick is a “subsystem.” In any system, when you focus on improving harmony and cooperation among all parts, you achieve greater efficiencies than when you emphasize or favor one part.
In the “stroke system,” propulsion isn’t the primary output of the kick subsystem. The dynamics of the stroke system are a bit more complicated than that.
Let’s focus on the 2BK as taught by TI, because that’s the “default technique” we teach in Perpetual Motion Freestyle. In PMF the primary contributor to propulsion is the weight shift. If we use an analogy with a powerboat, the weight shift is the “engine” for propulsion. The hands and arms are the blades of the propellor.
The energy source we tap for the weight shift is to get body mass and gravity to work together – mainly because that energy source is significant, sustainable and “low cost.”
The 2BK makes an insignificant direct contribution to propulsion, but a highly significant contribution to weight shift.
- When I add “snap,” I do it to downbeat.
- A right leg downbeat drives the left hip down.
- In a well-coordinated 2BK, there’s a left leg upbeat at the same moment . . . which becomes more dynamic because the stronger downbeat contributes to a sharper weight shift.
- And this helps propel the right hip up.
These stroke dynamics are taught in Lessons 3 and 4 of the Easy Freestyle DVD.