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Passive vs Active Movements

post #1 of 2
Thread Starter 

It is logical to say a passive movement is the object of action rather than causing action. One could also argue passive movement to be the lack of active movement; it requires no personal effort or attention and is automatic. But it is hard to fathom these definitions coexisting. If one were to argue flexion to be active because even though the skier is doing less work or in a sense becoming less active by resisting less pressure as the legs flex and absorb the pressure, It is still active because regardless of how much the skier is resisting pressure, any resistance decreasing or not is still exerting personal effort which by definition is active. If one were to be truly passive during flexion the skier’s body would simply fall to the snow at the rate at which the pressure and forces of the turn dictate. This explanation of flexion and extension being active seems reasonable.

The lack of reason begins when this theory of passive and active movements is brought back to rotary. It seems the common thought about rotary that has come to take place is that it is active when the action of physically rotating the femur rotates the ski, and it is passive when the action of tipping the ski results in rotating the femur. Going back to the definition, a passive movement is the object of action rather than causing action. The passive movement being the rotation of the femur and action being tipping which by definition does not involve rotation.

The problem lies within these differing ideas of what active and passive really means. If one were to look at passive rotation they would have to ask, does one have to apply any personal effort or is it just automatic? Well it seems we do not have any magic “tipping muscles” in our lower leg that could result in the passive rotation (no personal effort) of the femur. As a matter of fact it is rather impossible to tip our knee with out first engaging the muscles that rotate the femur. This movement most certainly involves personal effort which then by definition becomes active.

Now it seems the definition of Object and Action needs to be looked at. It could be argued that because the skiers focus is on tipping the ski the rotation of the femur is seemingly passive regardless of what muscles engage to accomplish the task. This would define the action as “focusing on tipping the ski” and the object as “the femur”. If this is the case then is it plausible to state flexion as passive? The action would be “focusing on letting your hips fall through the transition”, while “the gradual lessoning of resistance” would be the object. Skiers have different focuses all the time even though for the most part the general movements stay the same. If one has the focus of shortening the inside leg, the lengthening of the outside leg may seem passive to them. Or if they are focused on extending the outside leg the shortening of the inside leg may seem passive. If the skier is focused on a retraction move at the transition it seems pretty arguable that they will be flexing their legs very actively, but if the skier is simply relaxing and letting their body somewhat give into the forces pulling it down the hill it seems flexion has just become the object and the pressure and forces pulling it down the hill has become the action.

Is passive defined simply by not being active? Or is it the just an object of another action? Or can it really be as open in interpretation to vary upon what the skiers focus is? I am sure some of you are extremely set on what Passive movement is. I wish I had the same amount of understanding that could allow me to be set on what it is, but right now my understanding seems to contradict itself. I hope you guys have thoughts about the points brought forward. In many ways these thoughts are lacking and I hope to gain from your responses.

 

All is well,

Spaulding

post #2 of 2

Welcome to Epic Spaulding!

This concept of active vs passive does not have a lot of importance in mainstream ski teaching theory here in the US. It is a favorite theme of a popular writer who has been mentioned on Epic quite often (and needs no repeating). It's not that we don't understand this concept, we just use other words for it and put more emphasis on "active" movements because that's what skiers can control to cause desired actions. This avoids the problems associated with "differing ideas of what active and passive really means". You might find more interest in a detailed discussion of this topic on the popular writer's forum.

 

Part of your confusion may be coming from "relativeness". For example, if a skier is traveling across a smooth groomed slope, they will be using a certain amount of active muscle tension in order to remain upright (the ultimate passive movement would be falling flat on the snow). If single bump was suddenly encountered and the skier did not change anything, the skier would be lifted into the air. If the skier used a passive amount of flexion in the lower body they could absorb the bump and keep the upper body "level" to the "normal" snow surface. But that passive flexion is still a conscious movement.

With respect to tipping movements causing rotation of the femur, we have the concept of a "kinetic" chain. This theory is that certain movements biomechanically cause other movements to occur. We don't need the terms passive or active to describe a kinetic chain. Within PSIA we talk about effective and ineffective movements.  We know that turning the foot is an effective movement for causing a skid and that it can also result in turning the femur, but we know that this is not an efficient way to ski. Calling that an active movement and saying that the only proper way to cause a skid is to reduce tipping instead is certainly a legitimate approach for a teaching system to take. Personally, I prefer to let skiers make their own choices instead of labeling things as good or bad. It's our job as coaches to give skiers more options to choose from. This includes more effective and not necessarily more efficient options. This way we don't have to argue about passive/active, good/bad or right/wrong. If you want to talk about the role of femur rotation in skiing and the pros and cons of using tipping or foot steering to cause femur rotation, there are lots of folks here who can lend some insight.

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