Mark has skied for two winters and has only been exposed to standard ski instruction – involving snowploughs and “balance”. Despite his obvious persistence and determination the outcome is classic “survival skiing”. Nearly everyone would say in this situation that the issues were just because Mark needs to do it better – but the reality is that he is accurately doing what he was taught. The problem in the teaching. Time now to unravel this knot and put things right.The video clip starts off with Mark prior to any changes then the second two clips show the first changes beginning to come through.
The basic premise of classical teaching is to place the skier in balance (1) – with the skis spread into a “snowplough” giving a “polygon of sustentation” – meaning the centre of mass has to remain inside this polygon. Weight transfer (2) to the uphill ski is said to start the turn. An “up” motion (3) of the body is used during this initial weight transfer. Unfortunately the results of this complete heap of nonsense is a disaster – only generally mitigated by people successfully ignoring it – and this being mostly done unconsciously.
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“balance” is a complete fallacy. Dynamics is used in skiing – the opposite.
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The “weight transfer” causes the centre of mass to move in the wrong direction – making all skiing next to impossible.
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The up motion of the body prevents the skis from working – the timing is the wrong way around.
Mark was barely managing to circumvent it all by using shoulder rotation, heel pushing, twisting his feet, leaning on the back of the boots and generally doing a good job avoiding breaking something. I had planned on a reasonable period of warm up and getting used to skiing again – but cut that short to get straight to work sorting it out.Shoulder rotation – lack of support from the left leg…
Dynamics
We went straight into dynamics with my standard explanation and exercises. This is found on the fixed menu at the top of this page or here: http://skiinstruction.blogspot.fr/p/dynamics.html
The idea is to accelerate the body (centre of mass) directly into the new turn – to drive it pretty much as far from equilibrium as you dare to. For this forward speed is necessary – as it is on a bicycle. The skis sustain the process. Your job is simply to fall over – the ski’s job is to bring you back up. Notice – this means as on a motorcycle that you go down into the turn and come back up out of it. The timing is the same as walking or skating – the arc made by each outside ski being a stride. When someone is used to twisting the feet and skis and using rotation there is often very poor support for the dynamics to take place. For this reason we quickly moved on to looking directly at the feet.
Feet
The main issue here was to centre the stance over the front of the heel – just below the ankle joint. This trains the skier to flex at the knee and hip instead of collapsing the ankle. Keeping the weight off the front of the foot during flexion causes the anterior tibialis muscles (outside of the shin) to tense up and for the ankle to go stiff and supportive. Now the leg supports the body and not the ski boot during flexion. Pressure on the fronts of the boots is only to affect the function of the ski – not to take over from the ankle. Standing on the inside of the heel you can now rock the subtaler joint and so rock the foot from edge to edge. This is how the feet are controlled – rocking BOTH feet onto their inside edges simultaneously. On the turning (outside) ski this slightly turns the forefoot counter to the direction of turning.
Rocking the subtaler joint has a chain reaction right up to the hip through the adductor muscles (inside of upper leg). Tensing those muscles on both legs activates the core for stability and readiness. The knee moves inwards laterally by a small amount during this process. If in contrast the ankle is flexed and the knee pushed in there is nothing to stop it from fully twisting inwards and breaking. The photograph above of Mark skiing shows the knee actually outwards due to the foot being twisted in the direction of the turn. Boot alignment was checked and found to be adequate but not perfect – leaving the skis slightly under-edged. Next set of boots need to have a canting device in the cuff.
Skating
The above actions of the feet and legs are a natural part of skating. This extends even further into postural issues with the hip being tucked in beneath the pelvis when standing on the skating leg. The elementary skating exercises can be found here: http://skiinstruction.blogspot.fr/p/beginners.html
Pulling Inwards
To encourage Mark to work towards moving everything inwards in a turn we did what is normally a “pivoting exercise” where I blocked his ski tip from sideways motion with my pole and he tried to pull the tip with force against the pole. This simulates the way the leg needs to work – opposite to the sort of action that pushes the heel out. This helped mark significantly – especially when then refreshing the dynamics with the centre of mass.
Illusions
We had earlier discussed d’Alembert’s fictitious forces when working on dynamics. Centrifugal force is one of them! The “pulling in” is to work with the ski to generate “centripetal” force (towards the centre). The way visual perception works means that you can only actually see the things you understand. I’m sure that after today’s session many new things in skiing are visible to Mark who was very quick to understand each aspect presented.
Conclusion
Today was day one for real skiing for Mark – so patience is needed. Very good progress was made and can be seen clearly in the video. This progress will accelerate as more aspects are dealt with – such as fore/aft motion, pivoting skills, body management for protecting the hips and lower back and whatever details we can manage to refine. Mark needs to develop the skating skills and particularly the ability to sustain the pressure on one leg at a time – for the whole of each turn. All the twisting and heel pushing has deprived him of any opportunity to develop this basic skill over the previous two years.
