Working in Movement

I've referred elsewhere to the dynamic systems approach to movement education and the like, notably in the work of Esther Thelen on child development. Complex Systems As a Fundamental Theory of Sports Coaching is a presentation that takes a look at sports applications. It is a somewhat technical presentation, but there are a few good stories to be found.

For example, a control parameter is a term referring to stuff that (strongly) influences the behavior of a non-linear. Here is a non-technical story from the presentation that illustrates control parameters in terms of adaptation and learning in a critical situation:

Another example with direct personal consequences is the practice of the Parachute Landing Fall ("PLF") that is supposed to protect a parachutist from injury in the case of high-velocity impact on the ground. It is taught with a great number of details in the sequence of movements that should ensure that the contact of the person with the ground follows the sequence foot-lower leg- upper leg-hip- side of the torso. The theory behind this sequence is that as much as possible of the kinetic energy of the linear vertical motion to be converted into the kinetic energy of rotational motion while distributing the area of impact as much as possible.

During a paragliding accident I tried to follow these steps only to find out very painfully that I could not proceed beyond step one: By the time I tried to initiate the rolling movement my knees had already crushed my sternum and two of my vertebrae suffered compression fractures. There was a clear mismatch between the practice condition and the real-world requirement. During my first flight after recovering from the accident I got into turbulent air about 10m above the landing area with the consequence of a major collapse of my wing and the subsequent rapid descent. At that moment it became clear to me that the only rule that needs to be remembered in exercising the PLF is to avoid landing on ones feet while they are below the center of gravity. As soon as they are off center they will automatically produce the torque needed for the transfer of kinetic energy to rotational motion.

Learning comes in handy sometimes, eh?