The weather forecast for today was snow! ... and they trust computer modelling to predict our climate?
Alex, Tariq and JJ
Feet
Today the boys started off with an indoors lesson on using the feet. I asked Alex how many bones were in a foot and he answered correctly "26". There are also 33 joints and over 100 muscles and tendons. Over a quarter of the bones in the body are found in the foot - so in general we seriously underrate the importance of the feet.
Collapsing Ankle
First of all the boys, standing with feet hip width apart on a carpet in their ski socks, were asked to bend their ankles. They all allowed their knees to collapse forwards. This becomes disguised in a ski boot and instead of standing up people lean on the boot and stop using the legs properly. For this reason they often then end up next leaning on the back of the boot still looking for something to hold them up other than simply standing up.
Strong Ankle
The easiest way to strengthen the ankle is to stand on the heel with the forefoot on the ground but all of the weight passing through the heel. Instead of the ankle collapsing the only way that you can now bend is at the knees and hips - resembling sitting down. The muscle in front of the shin - the Anterior Tibialis contracts and the ankle goes strong inside the ski boot.
Rocking the Feet
The ankle joint is a hinge and only goes up and down. Beneath the ankle lies the subtaler joint and with this joint the foot can be rocked laterally. This is the required motion for skiing so the feet can be rocked from edge to edge corresponding roughly (not all all the time) to the edges of the skis. This action is easy to feel when standing on the heel bone. If the ankle is allowed to collapse then it becomes impossible to rock the feet and the knees get pushed into a twist from side to side which can become very dangerous for the knee ligaments.
Centre of Mass
Rocking the two feet onto the left edges causes the centre of mass to move to the left. I explained that the centre of mass is a point that we learn to use in sports. We spin or roll about this point - but it is not a point fixed in our body and moves around as we change shape. It's like the point of a pencil - not part of us but we can feel where it is when using it.
Adductor Muscles
Linking the foot to the centre of mass we find the adductor muscles on the inside of the leg - those could be called the "skating muscles". They allow us to pull the leg inwards. When rocking the feet onto the left edges it's the adductor muscles of the right leg that become tensed - pulling inwards.
Magic Point below the Foot
The ideal point below the foot to stand on is just in front of the heel. Like the centre of mass this is not a part of your body - it's a point to aim for. This is like a centering point for the foot and you always try to get back to it - and the boots help you to do so if they are any good.
Carving
Soon after we had warmed up skiing I introduced the boys to "carving" running along the edges of the skis - by using the rocking of the feet and motion of the centre of mass. They all did it very well and so it is captured here on video...
We worked on skating and improving skating skills and using skating to project the centre of mass towards the inside of the turn.
Sideslipping
Prior to attempting pivoting again we worked on sideslipping and using the centre of mass to control the sideslip and the angle of the skis against the snow.
Pivoting
I assisted each boy though a controlled pivot. The skier had to hold onto a pole for support and I'd guide him physically though the maneuver. Tariq caught on to the principle whereby through pole support (using his own pole planted in the snow) he could get his centre of mass downhill enough without changing the edge of the ski and then pull the front of the ski smoothly inwards into the turn while it remained on its uphill edge.
Assessment
During the morning JJ was lagging behind all the time and regressing back to his defensive snowplough and practicing the inappropriate coordination that I was trying to draw him away from. I constantly nagged at him and gave him a hard time - but nobody told me that the poor little mite was suffering from a fever and temperature! He was incredibly brave to just be out there and he never complained once about anything. Alex was becoming more parallel in his skiing all the time as dynamics progressively replaced his snowplough and Traiq was adapting very quickly to new coordination.
Sam, Max and Ed
Sam, Max and Ed are all strong skiers but with the typical limitations imposed though traditional ski instruction. They were filmed before changing anything and then we worked a little on dynamics before entering the slalom course and skiing a little off-piste.
Ed
Ed displayed the most natural movement pattern in general and I later found out it was because he had thought about it for himself - with a little help from "Top Gear". His basic timing was correct. On the more critical side his stance was excessively "two footed" and with a strong tendency to get caught on the back of the ski boots. The skis tended to be allowed to run out to the side to get on their inside edges - resorting to pushing them out to the side in shorter turns - which he tended to avoid.
Sam
Sam looked stronger when the turns were a bit faster and he could get more forces from the skis to play with. His weaknesses showed up much more at low speed. Basically the upperbody was being kept motionless and the skis were passing underneath the body. This was causing the hips to fall into the center of the turn - the skiing to be two footed and reactive - instead of proactively controlled by the centre of mass or active use of the legs. In short turns once again this led to a pushing out of the ski to get onto the inside edge and and blocking of the body facing downhill so that the skis could be forced around and below the body again - leading to a reversed timing (up/down).
Max
Max had the most pronounced two footed "heel push" with short turns - to the point of commonly ending up on the inside ski and risking falling over on anything icy. The static-ness of the upperbody was similar to Sam - also blocked facing downhill to an inappropriate degree - so as to be able to push the heels out.
Basically we have a problem here stemming from educational brainwashing that all skiing is done on the "inside edge" of the ski and that you have to face down the hill and immobilize the upperbody - to stay in "balance". This is reinforced by the use of carving skis which give very strong feedback from the inside edges - overwhelming all other aspects of skiing.
Dynamics
We started by working on dynamics - through the explanation and exercises on to practice and into slalom. With this understanding flying in the face of everything the boys had ever heard before quite a lot of questions had to be addressed and a lot of explaining given - which is fine.
Slalom was introduced as a technical exercise to show the sort of work required to extend dynamic range. The skier's limit is nothing whatsoever to do with "balance" but everything to do with his ability to fall further and further over before the ski overpowers him and brings him back up out of the turn. The end of a slalom turn is especially hard and so great athleticism is required to hold the centre of mass down low and inside the turn to keep the turn tight and effective. Sam demonstrated that he was currently the strongest skier at 31.78 seconds, with Max at 33.79 and Ed at 36.79. A good racer will manage between 21 and 22 seconds. Objective feedback like this backed up with intelligent guidance is one of the most effective ways to change your skiing level.
The dynamics were then taken off-piste for a short run in tricky snow. The only modification I mentioned was to use a "seated stance" to keep the feet and knees in front of the body. "Sitting down" would make you fall backwards on the flat - but facing downhill this is not the case. Dynamics will save you in tricky snow no matter if everything else goes wrong. We had worked briefly on the dynamics of getting out of a turn - like a motorbike being brought up and out of a turn. For this we had tried "hanger" turns where you stay on the outside ski through the whole turn transition and almost enter into the next turn on the same ski. This is a critical part of dynamics to master for off-piste because most people when tense actually do the opposite and hold back -not using the "lifting up power" of the outside ski to strongly finish the turn and commit to the next one. The turn is finished when the body is going across the hill perpendicular to the mountain with the skis flat - and this is part of a dynamic process so it cannot be sustained for more than a fraction of a second. This position is called "neutral".
Carving
We had a very brief attempt at carving. I used this to introduce rocking of the feet and the use of the adductor muscles. Both Ed and Max had trouble feeling the adductors when pulling the legs in - because they are so used to pushing outwards instead that this tendency even managed to overwhelm the "pulling in" exercises. This was the exercise when the skier pulls the ski tip against the resistance of my pole stuck in the ground. Eventually I had to go straight to pulling the knees together before they could identify where the adductor muscles were. Carving at low speed itself was predictably not a problem - only Ed surprisingly losing grip as speed increased a little - probably due to the feet being too close together for this type of skiing.
Skating
We had a brief attempt to show how skiing is really a form of skating and how correct timing uses the same muscular actions and rhythm. The "down/up" timing of dynamics - falling down into a turn and being lifted back up out - and "down/up" leg action of skating compliment each other. Finding the resonance is a bit like bouncing on a trampoline. If there is no use of the legs with this timing it's a bit like stopping a trampoline from working by going against the resonance. Skating itself is just a falling of the centre of mass between the legs and diverging skis. When this falling is exaggerated then the ski goes more on edge and starts to turn the skier - eventually removing the need for the skis to diverge. A real slalom racer skates straight down the hill and that's why he appears to "face downhill" with the upper body. Sam managed to connect with this quality to some extent.
Pivoting
Having identified the role of the adductor muscles in carving it made the introduction to pivoting very much easier. As with the boys in the morning I assisted each one though a pivot and then let them try for themselves by using their own poles for support. Pivoting is for "fall-line" skiing - a braking form of skiing for descending without travelling across the hill. It's useful for skiing bumps, steep off piste in deep snow, couloirs and anywhere that it's necessary to control speed when going straight downhill. The key to this is to keep both skis downhill of the centre of mass for security and to initiate the turns on the uphill edges - the edge changing taking place when the skis point directly downhill only (in racing it's when the skis are pointing across the hill). The pole support permits the centre of mass to move downhill without the edges changing and then the centre of mass pulls the front of the skis into the turn. The addutor muscles also help this process and the foot of the uphill ski can rock onto its inside edge while the ski boot keeps the ski on the uphill edge - this facilitating the use of the adductor muscles. I showed how this could be done on either ski or both skis and it was only the relationship between centre of mass and edge control of the ski that mattered. This is why many people ski off piste with a two footed pivot - although most "two footedness" in skiing is detrimental because it is not done for the right reasons. Pivoting is when skiing with the feet together is acceptable - that's why elite bump skiers have their feet jammed together. Carving and inside edge skiing is when it's best to have the feet apart so that the inside edges are more easily accessed.
I explained also that the "motionless" upperbody in short turns is an optical illusion. During any short arc the body is being propelled across the hill. If simultaneously the centre of mass is projected down into a turn then this cancels out the movement across the hill and gives the appearance that the body is held motionless and that the skier only uses his legs. Because instructors do not understand the principles and mechanics of Newton's second law (mechanics of disequilibrium) they are completely unable to comprehend what is really going on. It's easy for a trained eye to spot who actively uses the centre of mass - but impossible for the untrained eye to see it.
No comments:
Post a Comment