I apologize for the delay in taking the static preload issue to the next level; application to stance. There are a number of associated issues that I need to generate graphics and animations for. In the meantime a reader asked the following questions:
“1) Am I understanding “static preload” they way you want us thinking of it? That is “static preload” is the basic optimal stance for skiing.”
COMMENT: The static preload sets up the initial angle of the shank. It provides the foundation on which to build an SR stance. A number of factors, but especially excessive Zeppa-Delta Ramp Angle and arch supports, can prevent the setting up of the static preload. It is important to understand that the static preload is established by a reflex action. It happens as a result of relaxing the hamstrings-gastrocnemius muscles and allowing the weight of the body (CoM) to stretch them.
“This stance would be then modified to accommodate the forces and demands place on the skier’s body by speed, terrain, turn shape etc. In other words, the body once it has learned this optimal stance(s) it will then use the stretch reflex to maintain optimal balance in the Coronal or frontal (for aft) and Sagittal (left right) planes regardless of terrain etc. It is this vital sensitivity element that allows as skier’s brain to actually control the edge/snow interface to effortlessly locomote on skis.”
COMMENT: The stance is configured from the static preload that configures the triceps surae (soleus-gastrocnemius) in isometric contraction. Every day when you start skiing, you need to perform what amounts to a pre ski SR check. I will explain how to do this in a future post.
“2) There is a caveat of course; the boot must be mechanically able to permit the optimal stance(s), or “static preload”. ”
COMMENT: The structures of the boot must enable the 3-dimensional global articulations of the joints of the foot associated with the optimal stance characterized by the posterior chain of muscles (soleus-gastrocnemius-hamstrings) in isometric contraction.
“3) You are suggesting that the “static preload” be a learned experienced in bare feet so that the skier’s neurologic system will recognize the sensation both in skiing and boot fitting. Modern ski boots make both more difficult.”
COMMENTS: Yes and yes. I will explain why soon.