LET S UNDERSTAND SKIING By Prof. José Pepo Hanff

Transcription

1 LET S UNDERSTAND SKIING By Prof. José Pepo Hanff This work is dedicated to my professor and mentor Georges Joubert Georges and Pepo, France 1972 ACKNOWLEDGEMENTS In the first place I would like to express my appreciation to the Canadian Ski Instructors Alliance (C.S.I.A) which during the 1983 INTERSKI Congress held in Sesto, Italy, presented as its theme the notion of Movement and Motion. This triggered my interest in the concept which motivated more than a dozen years of research and development on the subject, the outcome of which is, among other things, this work. My gratitude to my brothers; Ernest, an engineer by profession, for his help with the physics applied to skiing, and George for his help in the configuration. Thanks also to my friend and colleague Colin Oke for his help with this translation. Last but not least, my deepest appreciation to my best friend and wife Ana Luisa without whose unlimited support and encouragement this document would have never seen the light of day. Santiago, Chile April 13,

2 INTRODUCTION For more than a century Alpine Skiing has been a very important factor in the economy of several European countries. Due to the intense competition between those countries to gain for themselves the same customers, they developed a look of their own to differentiate from the rest. This specific look for each country s skiers required its own teaching method which would lead to the development of that particular image. This policy had very negative consequences for the sport. With the development of new technologies in the manufacturing of the skiing implements and the new techniques developed by the world best ski racers, skiing required important changes in the mechanisms utilized to obtain the highest performance. A look that at a certain point in time might have been efficient, was incapable of adapting to the changes that the new technical developments required because the methodology used was directed towards the development of that specific image. The teaching methods developed to look within an immutable image accepted by the national group, forced instructors and coaches to teach stereotypical gestures instead of searching for excellence and adapting themselves to the personal characteristics of each individual. The national techniques, used in achieving a specific look, required a rigorous and dogmatic progression which totally disregarded the personalities of the students, their personal needs, and the option of an open door to changes and evolution. In addition to this, since the sport of skiing exists, it has been taught based on the movements and actions observed as necessary to carry out the sport. This was and continues to be extremely detrimental due to the fact that the sensors which humans possess to see and feel the mechanisms required to perform the sport are extremely insufficient and misleading. Likewise, the approach more recently used to teach skiing based on each one s own sensations, observations and perceptions and in individual discovery is equally harmful and ill fated because it is also based on those scarce and limited sensors which lead us towards a cul de sac. In my opinion, in the specific case of skiing, once you have reached a good level of execution, it is necessary to reach an abstract understanding of the mechanics involved in skiing in order to be capable of performing a correct analysis and thereby be able to continue progressing without limitations. The ideal path to follow is to have a proper mental attitude, an excellent physical conditioning and an effective understanding of the sport to achieve meaningful knowledge. 2

3 A large number of books written on skiing are more focused on the psychological aspects of the sport rather than on the mechanical aspects: Inner Game of Skiing by Gallwey, Centered Skiing by Mc Cluggage, and Esquiar con los Pies by Guerrero to mention a few, are very focused on the subjective aspects of the sport. It is indisputable that a proper mental attitude is a prerequisite for good neuromuscular performance. Nevertheless, this can t substitute for an appropriate understanding of that which you are trying to perform. An outstanding violinist does not play based only on mental and psychological preparation. They are only the final touch to years of objective preparation to build a solid technical foundation to be able to achieve the perfect performance. Physical condition, mental attitude and technical ability are closely intertwined. My intention isn t to lessen the importance of the first two. Nevertheless, in the case of this particular study, the object is to make it possible for the skier who reads this to make an abstract image of what is truly happening while skiing and that the skier understands it so that the he/she can develop his/her technical ability to its maximum expression. What is here written is based on extensive observation and research of the way world champions ski. Great racers achieve maximum performance with minimal expenditure of effort and energy. By making optimal use of the external forces that are acting on them, they accomplish maximum effectiveness and efficiency. Who has not at one time been flabbergasted by racers, like Alberto Tomba, as they whiff through a slalom course apparently without difficulty? Like other geniuses in painting and music, these artists express themselves in their own way and with their innovations they make ski technique progress. Some racers only perfect the technical level achieved by their predecessors. Others like Killy, Stenmark, Tomba and more recently Miller and Maier innovate in the ski technique to such a point that they launch a new landmark. Certainly their inspiration would have been insufficient if their technical foundations would not have been right. It is wise to analyse and sometimes to copy the technique of the masters. Although this document is based on solid scientific arguments, I will try not to sink too deeply into the physics and biomechanics of skiing in order to keep it legible and understandable to anyone. Although I have tried to simplify as much as possible the concepts here explained, this document has not been written for the layman. It has been drawn up for the serious skier, for the racers and for the sport professionals. Because it isn t easy reading, it must be studied carefully. The person who decides to immerse himself/herself in this study will have to do it with an open mind. He/she will have to get rid of preconceived ideas and try to understand exactly what is been described and explained without making associations with previous concepts. 3

4 Skiing displays the vastest amount of situations, conditions, experiences, environments, and an enormous range of permanent changes which place an eternal challenge to those who practise it. Surfing and windsurfing to mention a few are other sports that show similitude to the situations and sensations found in skiing; nevertheless, none of them have the extreme variety that skiing presents. It is impossible to analyse in detail all that is happening at each instant while skiing. However the general approach here presented is equally valid. It was not my purpose when I wrote this document to compose a manual on how to teach skiing or an article on how to learn it. The objective is, as the title indicates, to explain the mechanisms that really occur while skiing. I have written this document specifically for the following readers: * For the assiduous skier who has more than a casual interest in this sports technique and who wants to improve his level, but doesn t know how to do it because he/she is limited by a poor comprehension of what is happening when skiing. * For my ski instructor colleagues, so that, with this new viewpoint of our sport, they will be able to analyse their students more accurately, not focused only on what they see as errors but also to understand the cause of those errors and therefore be able to correct them at their roots. * For my coaching colleagues so that with a better comprehension of the ways to achieve a higher performance, they will be capable of focusing their activity in such a manner that they will be able to accomplish a radical improvement in the performance of their racers. Most concepts described in this study are applicable to snowboarding as well. With the obviously necessary adaptations required for a different sport, snowboarders will also be able to benefit from most of the information here supplied. 4

5 CHAPTER 1 DEFINITION I have always been of the opinion that one should always agree on a definition of what is to be analyzed before proceeding with the analysis so that all parties involved will be speaking in the same language, that is, when I describe something in the next chapters, my readers will not end up understanding something else because we started up on different premises. After long discussions with my colleagues I have reached a simple definition of alpine skiing which, without going into details, gives us a real description of what skiing is all about: A person is skiing when, while standing on special implements called skis attached to the feet, slides in control down a snowed hill as the result of a component of the force of gravity acting on him. For me the words in control could be excluded from the definition. In my opinion the person is skiing both when he is in control and when is not. The control he has over the skis only indicates the level of development of his technique. The better skier being the one that has a more refined control over his skis. Nevertheless, for the sake of agreement with my colleagues, I will leave the definition as is. CHAPTER 2 THE POINT OF REFERENCE According to the definition, skiing differentiates from most other sports due to two reasons. In the great majority of sports that we humans practice, the movements and actions that we make to carry out the sport are the result of our own muscular efforts. For example in athletics, tennis, gymnastics, in group sports like soccer or basketball we propel ourselves by our muscles. When we kick a ball, jump or run, it is our own muscles that are performing them. Here we find the first major difference; a person when skiing is not generating his motion. His displacement is the consequence of an external force, the force of gravity (actually a component of it) pulling him down the hill. He does not need to do any kind of muscular effort to ski down a hill. It is sufficient to have the skis pointing towards the bottom to start skiing straight downhill just standing on the skis. In that case his only effort would be to maintain balance. We can therefore conclude that a person is skiing when he is in a sliding motion in relation to the ground. It is irrelevant how many movements we make with some segments of our body in relation to other parts of it. There is no skiing as long as we are standing on our skis on the snow without sliding. 5

6 In other words, the most important factor is the sliding displacement of the skier in relation to the reference point snow (or ground or floor or earth, whichever is the easiest one for you to understand). The second great difference is directly related to the first one. As I mentioned before, in other sports, as we need to move or kick a ball we do so by motoring internally with our own muscles, that is, the motor is oneself. In skiing, while we slide straight down as the result of an external motor which is the gravitational force, the way to deviate from that straight line is by indirectly acting between the snow and the external forces that play on you, by means of the implements-skis, carrying out actions that affect the way in which the skis interact with the snow. As you can see, what is relevant here again is the ground. From the former we can conclude that in contrast to most other sports where the primary point of reference in relation to which the movements are made is our own body, in skiing the primary point of reference should be the ground. Due to this, all the analyses of the movements our body makes to be able to ski, should be studied in relation to the primary point of reference, that is, the snow, and all the analyses that need to be made of movements of our body in relation to other parts of the body must be evaluated as secondary points of reference within the general context of the primary one. An important additional advantage accomplished by using an external element to the skier such as the earth as our primary point of reference is that automatically the external forces involved acquire the importance and relevance they deserve. Let s study an example: How many times have you been sitting by the window on a train or subway which is standing in the station with another train next to it? Suddenly you see that your train has started to move, and discover a few seconds later that it wasn t your train but the other one that was moving. What happened was that you thought that your own train was moving because your brain reached that conclusion on the basis of the wrong point of reference, which, in this case, was the other train and not because you saw your train actually move. It will start to move only when it does it in relation to the primary point of reference which is the ground. In skiing often the same thing happens; we see and analyse movements which are made with parts of our body in relation to other parts of our body, without taking into consideration the fact that what is relevant is our displacement in relation to the ground and the interaction of the implement-ski with its snow to achieve the desired trajectory. What s more, during hundreds of years skiing has been taught based on the movements that were made with certain parts of the body in relation to the rest of the 6

7 body, and, when mention was made of the movements in relation to the snow, it was usually done without even noticing that the point of reference had been changed. CHAPTER 3 OUR SENSORS Like a computer the human brain depends for its analyses on information that comes from sensors. These sources send messages with the required information so that the brain can reach conclusions. Unfortunately the human body was not originally built to ski; therefore, it doesn t possess suitable and reliable sensors to pick up the right information. This often leads it to wrong conclusions. As an example let s do the following analysis: If we stand at the top or the bottom of a slope and look at a good skier making short radius turns, we can observe that his upper body barely moves and that his lower limbs move from side to side in relation to it. Our brain reaches the conclusion that skiing probably consists of moving the legs from side to side. Then we start skiing making similar small radius turns and we feel that our legs move successively from one side of the upper body to the other. This only confirms what we saw before, the two sources of information reconfirm each other and the brain infers that to link ski turns consists of a displacement of the skis from one side of the thorax to the other by means of muscular actions that displaces the limbs laterally. But is that what really happens? Definitely not! If it did, as we look at the marks left on the snow by the skis, we should see an interruption of the tracks at the end of each turn as the skis are drawn over to the side by the lateral displacement, and they would start the next track to the side a bit higher (see image Nº1-A). Nevertheless the tracks left by a good skier on the snow do not look like that; they are a continuous line with the shape of an S, without interruptions between turns (image 1-B). 7

8 Image 1-A shows how the tracks would be if it were the skis that change sides. On image 1-B we see the tracks normally left by skilled skiers. Then, what is it that really happens? The problem is that our brain was deceived by two types of sensors that gave it the wrong information which caused it to arrive at the wrong conclusion. The first sensors were our eyes. They were looking from a point of view that didn t allow them to see the primary point of reference, that is, the displacement of the skier in relation to the ground. From where we were looking, we could only see the movement of the legs in relation to the upper body which is a secondary point of reference. (See image Nº2). 8

9 In this series of overlapped photos we can observe what we normally see when we look at a skier from the bottom of the hill, making short radius turns. It gives the impression that it s the skis that move from side to side. On the other hand, when we analyzed our own execution, we used the second set of sources: they are sensors located in our joints which tell our brain the relative position of the body segments to each other. If we put a hand behind our back, we don t need to see it to know where it is. But, as I mentioned before, the position sensed was in relation to another part of the body and not to the primary point of reference (the ground) which led it to the wrong conclusion. The irrefutable and indisputable proof that what we see and feel is not what really happens are the tracks left by the skier on the snow. Well then, I ask again, what is it that really happens? 9

10 CHAPTER 4 THE POINT FROM WHICH YOU LOOK To be able to see what really happens you would have to look at the skier from a point which is very difficult to achieve, that is, vertically from directly above the skiers head (see figures Nº 3 and 6 below and image comparison on page 15). This is the ideal point from where you can observe and analyse the skier in an integral manner taking into consideration the primary point of reference in its true relevancy. If we were to look at the skier from above his head during his global displacement or motion downhill, we would see that at the exit of each turn his centre of mass accelerates cutting diagonally across over the skis to the downhill side. Said in a different way, it is the hips and the lower torso (the area closest to the centre of gravity) that cross diagonally forward and downhill over the skis and not the skis that cross under the hips upwards. This acceleration of the centre of mass over and across the skis is the consequence of certain muscular actions that allow the external forces to pull it over to the other side. Our sensors perceive that now the feet are on the other side of the pelvis without recognizing the reason for this change due to their incapacity to relate neither to the primary reference point nor with the fact that the skier is in motion through space towards the bottom of the hill under the effect of an external force. Some years ago, while I was director of the Blackcomb Ski School at Whistler, Canada, as part of my research on this subject I asked our cameraman Budggie to film us from a chairlift I had stopped for that purpose. With a good number of instructors we did a series of short radius turns and also 2 giant slalom turns with the transition from one to the other right under the camera from a vertical perspective. The resulting video was an irrefutable proof of what is here stated. Each instructor or coach who has the opportunity to do this kind of filming should do it. Nevertheless there will always be someone who will say that both things are the same. That is definitely not so. If the perspective of the ground is used, we clearly see that the events happen as described above and it is true that as a consequence of this, the feet end up at the other side of the hips. But if we make the statement that we have moved the skis to the other side of the hips we have changed our point of reference and now we are relating the position of our boots to a part of our body (our hips) therefore the point of reference are not the same. The muscular efforts to make these two very different actions are completely dissimilar. The magnitude of the efforts required doing one or the other and the amount of energy saved or wasted is enormous. One should never make changes in his point of reference without being aware of it. 10

11 Images Nº3 and Nº6. Sequences of photos that show what really happens when we ski. On them we can clearly see how the center of mass crosses over the skis to the downhill side pulled by the outside forces. The sequence shown on image Nº3 were taken at the same time as those of Image Nº2 (above) but from the different point and correspond to 1,3,and 4 of that sequence. An image comparison of the two views can be seen on page

12 Superb photomontage by Ron Lemasters published in his spectacular web page: For didactical purpose we have added a purple and a green line to show the trajectories of the skis and of center of mass. Here we can observe how Miller, using an extremely efficient technique, makes the trajectory of his center of Mass as short and as uniform as possible. From positions 4 to 7 and 10 to 14, notice how his hips cleanly cross over his skis. 12

13 CHAPTER 5 THE IMPLEMENT (or tool or device) SKI. Everything a skier can do while he slides over the snow is thanks to those devices attached to the feet called skis. As I mentioned before, the skier uses these tools by generating muscular activity processes that affect the interaction between the implements and the snow. Through muscular actions the ski tool can be made to interact with the snow in three different ways: * Changing its orientation or direction. * Changing its angle of support with the snow in its longitudinal axis. * Changing its shape and the intensity of the pressure it exerts on the snow. To have a term when we refer to this 3 ways we can make the skis interact with the snow we will call them Foundations. The ensemble of muscular actions that work to control these Foundations will be called Mechanisms. That s how there are: * Mechanisms to control the orientation. * Mechanisms to control the edging. * Mechanisms to control the pressure. The desired ski-snow interaction will be the result of the combination, quantification, assemblage, coordination, orchestration, harmonization, and integration of these mechanisms through motoring actions or movements that the skier makes while he is journeying down the hill as a result of a component of the force of gravity acting on him/her. For a better understanding, we have designated these motoring actions as Skills. Therefore, the Skills are the actions which: *Combine the mechanisms. *Assemble the mechanisms. *Coordinate the mechanisms. *Harmonize the mechanisms. *Integrate the mechanisms. Due to the infinite and permanent changes that occur while we are in motion through space sliding on the snow, our dynamic equilibrium is continuously affected, and to be 13

14 able to properly execute the mechanisms mentioned above, we need to be in good balance. To achieve this, the skier must control his balance by means of the Mechanisms to Control the Equilibrium. These mechanisms are the infrastructure or bedrock which sustains the execution of the motoring actions that we make to affect the ski-snow interaction, with the goal of changing ski trajectory. In short, the mechanisms to control the equilibrium provide the base over which you execute the other three sets of mechanisms to achieve the desired trajectory. Due to the fact that, while we ski on the implements-skis, they rub against the snow, it is the resulting friction between the two which allows them to interact. It is impossible to perform mechanisms to control one FOUNDATION without affecting the others. Nevertheless, it is crucial for the skier to understand and separate the mechanisms in his mind with the goal of been able to combine, quantify, assemble, coordinate, orchestrate, harmonize, and integrate all three sets of them. It is impossible to become a competent and efficacious skier if we confuse and mix the muscular actions that control the different mechanisms. It is essential to understand and to try to control each mechanism independently, adjusting and quantifying them separately to be able to achieve the finesse required for each, to finally achieve the precise trajectory required for our skis in accordance with the specific conditions of the moment. 14

15 IMAGES COMPARISON Pictures taken of the same turn from 2 different points. (For comparison purpose eliminate the second position of the skier on image Nº3) What we see What really happens!!! CHAPTER 6 THE MECHANISMS IN DETAIL THE MECHANISMS TO CONTROL EQUILIBRIUM These are the motor actions which maintain the skier in dynamic balance as his equilibrium is disrupted by external forces or by his own movements. There is a large array of actions we can carry out to keep our balance while skiing: forward, backward and lateral inclinations, movements of the arms and poles, spreading or feet, torsions, flexion or extension of a leg, etc THE MECHANISM TO CONTROL THE REORIENTATION These are the motor actions of the muscles that are made to reorient the skis into the desired direction. 15

16 There are several ways to make re-orientation efforts, for example, rotation of the upper body, counter rotation of it, anticipation and blockage of the upper body, etc. Nevertheless, because of its efficiency, the action most often used in modern skiing to redirect the skis is the rotation of the legs in their vertical axis around the hip joints. THE MECHANISMS TO CONTROL THE EDGING These are the motor actions intended to augment, diminish or maintain the angle between the base of the skis and the snow in their longitudinal axis. Although a global inclination of the skier s body towards the inside of the turn will affect the edge angle, this action should be used exclusively as a mechanism to control the equilibrium, specifically the lateral balance. If we use this mechanism as an action to control the edge angle, we will impair our balance. Also, the angulation of the knees to the inside of the turn will increase the edging. Nevertheless, because of the knees anatomical characteristics, this manoeuvre requires a rotation of the whole leg around a vertical axis on the hip joint which, if performed by itself, makes it a mechanism to control the re-orientation. The appropriate action to control the edging is what s called global angulation. This manoeuvre, if we use it to increase the edge angle, consists of a simultaneous rotation of the hips and knees; while the lower limbs rotate around a vertical axis on the hip joint to angulate the knees to the inside of the turn (for example clockwise), simultaneously the pelvis also rotates to the inside of the turn but in the opposite sense (in our example counter clockwise) by means of the inter vertebral joints, to maintain the thigh bone longitudinally aligned parallel to the ski in the horizontal plane. 16

17 Image 4-A; photo of Canadian racer Thomas Grandi from publicity add for the Rossignol brand published on the Spring 2005 Canadian issue of Ski Press Magazine. On it we can see a perfect example of Global Angulation. Image 4-B; photo of Swedish racer Anja Paerson from publicity add for the Salomon brand published on the Fall 2004 Canadian issue of Ski Press Magazine (action: Pentaphoto). On it we can also see another excellent example of Global Angulation. On both pictures take notice of the thigh aligned lenghtwise parallel to the ski on the horizontal plane. 17

18 The Global Angulation is the only mechanism for the control of edging that doesn t directly interfere with the other mechanisms, and that is also anatomically correct, therefore, doesn t put abnormal loads on the joints. THE MECHANISMS TO CONTROL THE PRESSURE These are the motor actions intended to increase, decrease or maintain the pressure exerted on the skis to change or hold their shape. This deformation of the ski will make it interact with the snow in the manner we are looking for to obtain the desired effect. The shape of the skis can be changed by means of various actions: Moving the upper body back and forward, displacing the feet back and forward, by flexions and extensions, by changing the foot-hold from one foot to the other, etc. and any combination of the above. Nevertheless, all these motor actions will not achieve the desired results if they are not used in perfect combination. Each motor action must be executed in the exact proportion (quantification), at the precise moment (rhythm) and must be combined in a meticulous and orderly way with the other ones (coordination) to obtain a harmonious whole. CHAPTER 7 LET S APPLY THE ABOVE As I stated in chapter 1, since its beginning, the Sport of Skiing has been taught based on the gestures and actions observed and felt while practicing it. This was, and continues to be extremely negative because the sensors which the human body has to see and feel the mechanisms of execution are extremely insufficient and misleading. How often have you heard instructors telling their students to plant their pole at the end of a turn and to simultaneously increase their edging to create a solid platform from which to make an energetic extension to un-weight the skis; then, once the skis are weightless, to displace them laterally to the other side of the hips so that they change edges to be able to make a turn in the opposite direction accompanied by a flexion. Analyzing what I just described, all those actions require an enormous expenditure of energy: When planting a pole and setting an edge, we are breaking our glide, we constraint our inertia and we obstruct the component of the gravitational force that makes us ski. When extending, we are also contending gravity. When we push our skis to the uphill side, we are battling gravity again and pushing the skis in the opposite direction to the way they naturally want to go. 18

19 Imagine yourself skiing without making any of these efforts!!! Actually it is very easy; all you need to do is to allow the forces that act on you while you are skiing to do the job instead of your muscles. As you are making a turn by means of a coordinated utilisation of the MECHANISMS described in the former chapter, the resulting vector of the sum of the centrifugal force plus the gravitational force component, passes through the centre of gravity and the inside edge of the outside ski of the turn you are making. All you need to do to start another turn in the other direction is to change the geometry of the vector, deviating it from the edge to the outside of it so that now it will pass from the centre of gravity to the outside and downhill from the outer ski. In other words we must do actions which consist in controlled muscular relaxations to permit the external forces to take our centre of mass to the other side of the skis. Image Nº5 Photo sequence of the famous Swedish racer Ingemar Stenmark competing in Oslo, Norway in This sequence of photos was made by my university classmates James Major and Olle Larsson and displayed in their excellent book published by Poudre Publishing Company World Cup Ski Technique pages 114 and 115. On it we can see that it is not necessary to raise the camera very high off the ground to remark the displacement of the centre of mass over the skis in relation to the snow. 19

20 STEP BY STEP DESCRIPTION AS WE SKI * We are at the exit of a turn, already past the fall line. At the desired point we initiate the actions required to start crossing over the skis: we begin to flex the outside leg of the present turn and simultaneously we cease edging that ski on its inside edge, giving way to the forces that pull us to the outside of the turn. * While the skis continue turning in the same direction as a result of the rotary inertia, complemented by a rotary muscular action of the lower limbs, the hips and knees begin to cross over the skis in an oblique path forward and downhill to the other side. * To insure that the ski does not tend to sideslip as it flattens out by the displacement of knees and pelvis, we add a slight muscular effort to bring the outside leg to the medial plane. * The preceding turn continues until approximately the moment in which the hips stand directly square above the skis. This displacement has put the skis flat to the snow. * At this instant the skis have stopped turning and for a few thousandth of a second they only slide forward. * The body has taken a wound up position around its vertical axis (like a corkscrew) as a result of the rotation of the legs to finish the turn. Now the thorax is facing forward and downhill and the feet much more to the side. * The coiled body now starts to unwind by a new muscular rotary action of the legs in the opposite sense. This is possible due to the decrease in pressure and diminished friction, offshoot of the flat skis. Also to the important difference of masses between upper body plus pelvis and the legs. * A hundredth of a second later, the hips and knees have crossed to the other side of the skis which causes them to edge to the inverse side, on the new edges. * Simultaneously we initiate an active extension of the new outside leg. This leg had already started a passive flexion followed by a passive extension as soon as the hips started to cross over. * The pelvis and knees continue to move inwards of the new turn gradually increasing the edging. * Also the active extension of the leg progresses which increases the deformation of the new outside ski. 20

21 * The coordinated and perfectly quantified combination of Edging, Pressure and Reorientation Mechanisms allow us to carry out another highly efficient turn. NOTES RELATED TO THE STEP BY STEP DESCRIPTION * This is a very general depiction. While skiing, the enormous amount of variety of situations, external conditions, and the rainbow of changes that permanently occur make it difficult to imagine these actions applied in all cases. Nevertheless, the principles that back the above are always valid. * The extension of the new outside leg does not start to be active until the skis have changed edges. If it starts before that point it will cause an unnecessary deviation of the trajectory of the centre of mass, moving it further away from the ground unnecessarily. Additionally, this will increase the friction between the skis and the snow needlessly. * The purpose of the active extension of the new outside leg is to put pressure on that ski and thereby bring the aforementioned vector back to the base that sustains us. If this extension does not start at the moment the edges change, the skier will probably loose his balance to the inside of the new turn. * The procedure to change edges starts much earlier than the actions to change the pressure from one ski to the other. As I explained above, the active extension is the means by which one transfers the pressure from ski to ski and this action should start only when the skis enters onto the new edges. * Nowadays, the opinion is propagating among professionals that as a consequence of the more pronounced side cut of modern shaped skis, the Mechanisms to Control the Reorientation have become irrelevant or simply aren t utilized any more. I do not agree with that assumption. I consider these Mechanisms extremely important during the interval from the moment the centre of mass starts to cross over the skis until we get on our new edges. At that stage the pressure, and therefore the deformation of the ski, diminishes. Edging also decreases until it reaches zero. That only leaves us the Mechanisms to Control the Re-orientation to continue guiding the skis precisely through the desired trajectory by means of rotary muscular actions. * To achieve maximum efficiency while skiing it is necessary to maintain the trajectory of the centre of mass as rectilinear and uniform as possible. What s more, this is not only valid in the sense that it shouldn t deviate more than necessary from it s horizontal and vertical path, but the upper body shouldn t turn on its vertical axis in the direction of the turn more than needed be. As a secondary, but not less important consequence, the wound up body that this blockage of the rotation leads to, benefits the re-orientation mechanisms that follow. 21

22 * Take note that many of the actions that the skilled skier carries out to trigger the next turn are done during the preceding turn and not at its end. Therefore, it is unsuitable to think of skiing as turns that start and finish but it should be understood as a whole from the moment one stars sliding until one stops. For example, the skier starts to do the actions which trigger the passage of the center of mass downhill over his skis while he continues with actions that allow him to go on turning in the same bearing for an additional period of time to finish off the turn in that direction. This means that: 1.- The actions to the change of edges starts before the end of the turn. 2.- The rotary efforts that are being applied should not be interrupted at the moment the process to change the edges starts but should continue until the moment that, due to the passage of the center of mass over the skis, they become flat to the surface of the snow. 3.- That one shouldn t create a platform on which to search for a foothold to trigger the actions necessary to start the next turn. 4.- That the human body can perform several simultaneous actions with different muscular groups that are aimed at achieving seemingly opposite goals. As a means to prove what I have just stated without leaving the slightest doubt, I will use the following spectacular photomontage of the great Austrian ski racer Hermann Maier, made by Ron LeMaster. Image Nº8 Photomontage of world cup racer Hermann Maier, by Ron LeMaster. To see all of Ron LeMaster s exceptional work go to his magnificent web page: 22

23 Here we can observe that: a) At the beginning of the sequence while turning right, in positions one and two, his left hip and knee are angulated and his left leg extended. b) Most important, in position three of the sequence, we can clearly see by the direction of the skis and the spray of snow that his right turn has not yet finished but his pelvis (hips, center of mass) has already started to move downhill over his skis, showing his angulation and edging obviously diminished. c) Only in position number four, once his pelvis is square over his skis, which are now flat to the surface of the snow, does the right turn end. CHAPTER 8 THE POLE PLANT For too many years the pole was taught to be planted at the end of the turn as the period to end it (like the period at the end of a sentence). Together with the plant one was supposed to set an edge to use it as a platform to extend the legs so the skis would be un-weighted which allowed us to make a new turn in the opposite direction turning around the pole. Nowadays, that approach is totally obsolete. From being an action which ended something and triggered others, presently the movement to advance the pole for the plant is activated by other actions, and its purpose is mostly to harmonize the other movements. With variations that depend on the innumerable variables like the type and size of the turn, snow conditions, speed, degree of steepness, etc. when the pole is planted, it s done as a timing device, as a balancing device, and as a movement coordinator. Generally speaking, the sequence of actions to plant a pole is as follows: * At the exit of a turn, the instant we start our first actions to permit the crossing of the centre of mass over the skis, simultaneously, we start to move the tip of the outside pole forward by a movement of the wrist and fingers to position it for the plant. * The pole reaches that position during the interval the pelvis takes to move to be square over the skis and it touches the snow around the time the skis are flat to the ground. 23

24 In this photo sequence we can see that on the first skier s position the pole has already begun to move forward, simultaneous to the beginning of the crossing of the hips downhill. On the second position, the moment the hips are square to the skis that are now flat to the ground, the pole touches the snow. NOTES IN REGARDS TO THE POLE PLANT * It is the beginning of the actions with the lower limbs which trigger the start of the movements with the upper limb to position the pole. * To use the planted pole to turn around it, hinders the free flow of the hips downhill; therefore, it is completely contradictory to our approach and our concepts. * In short radius turns where the Mechanisms for Reorientation are more consequential, the pole is planted earlier and it contributes to stabilize the upper body in such a way that, when the new rotary movements of the legs are made, it doesn t tend to turn in the opposite sense. * In certain types of turns the planted pole helps to increase the base of support. * When we look at world cup races, we notice that the racers only plant their poles now and then and almost exclusively in Special Slaloms. Rarely will we see a pole planted in Giant Slalom and never in Super G or Downhill. This only proves that the pole plant is not an essential action at high end skiing. CHAPTER 9 EXERCISES At the beginning of this document I stated that it was not my purpose when I wrote it, to compose a manual on how to teach skiing or an article on how to learn it. The objective was, as the title indicates, to explain the mechanisms that really occur while 24

25 skiing. However, in response to many reader s requests, I have decided to add an extra chapter in which I give a brief description of a series of exercises which I have created or compiled from other sources which I use with my students to develop their capacity to allow their center of mass to be pulled over the skis and to maintain it s trajectory as uniform and rectilinear as possible. I do not like to teach exercises in a theoretical way without the advantage of seeing the student performing them to be able to guide him/her properly. In my opinion the Skier Analysis is the most important tool the instructor has. By teaching the following exercises in a theoretical way, I will be doing it without this essential tool. By means of the following exercises, the skier will be able to develop the skills described in the former chapters without necessarily understanding the theoretical concepts previously described in this article. I will divide the exercises in relation to the level of development of the mechanisms mentioned in chapter 6. Each one of this development levels has a Model of Reference. As an introduction to the displacement of the Center of Mass for those skiers who consider the snowplow turn as their Model of Reference, I suggest a couple of exercises which you can try once you can perform your snowplow turns with ease: 1.- FLATTENING THE INSIDE SKI Each time you start to make a new turn, accompany the actions with an effort to flatten the inside ski of the turn in relation to the surface of the snow. 2.- SIT ON YOUR HEELPIECE Each time you start a new turn, try to feel as if you sit a little over the heel piece of the inside ski by displacing your bum towards the inside of the turn. For those skiers who ski with their skis almost always parallel and therefore consider the basic parallel turn as their Model of Reference, there are several exercises: 3.-SHIFT THE KNEES On a green run, as you come out of a medium size turn with your skis in a wide stance (not less than hip width), finish your turn by shifting your knees from the side they are at (that is the uphill side) to the other side (downhill side). It is essential that during this phase you refrain from making any kind of effort to initiate a new turn. You must feel that your skis deviate downhill by themselves, absorbed by the gravitational component due to the fact that, by shifting your knees from the uphill to the downhill side, the skis flatten out and eventually change edges, which allows the external force to pull them down. The next turn should start by itself, not as a result of a turning effort on your part. Any kind of effort you add to start the next turn will be detrimental to the intended objective. During the shifting of the knees our main concern should be to maintain our balance, not to start a new turn. Patience is the key word. 25

26 4.- THE This exercise is similar to the one above, but the skier must have his mind focused on the edges of the skis instead of on his knees. As you come out of a turn, you are skiing on two edges of the same side. What you must try to do is to flatten your skis to the surface of the snow so that they slide on all four edges for a brief instant and then shift them to the opposite two edges. 5.- THE TUBES On a green run, while making medium size turn with your skis in a wide stance (not less than hip width), imagine that your skis are sliding lengthwise along top of a pair of PVC tubes of a diameter similar to the width of the skis. These tubes are lying on the ground parallel to each other making medium sized curves. It is as if we are trying to ski following the S shaped curves these tubes are designing while lying on the snow. Now each time you arrive at the point in which the tubes stop turning to one side and start turning to the other, you must roll the skis laterally over the tubes without allowing them to slant across the line of the tubes, which means keeping them parallel to the tube above which they roll. For those skiers who ski with their skis almost always parallel and therefore consider a more refined parallel turn as their Model of Reference, here are some more exercises: 6.- NOISE-SILENCE-NOISE In this exercise you must focus on what you hear. You are making medium size turns on a blue run. During the turn you hear the skis making noise against the snow. The idea is to try to create a period of silence between the noises of each turn by means of an action of flattening the skis to the surface of the snow, allowing them to glide forward and downhill without making any noise during the time between the turn just finished and the next one. THE STOOLS While you are making ample turns at a good speed on a blue run, imagine that the angulated position is achieved by sitting on a stool located on the outside of the inside ski, beside the heelpiece (something like what you see on image 4-B on page 15 but less exaggerated). To start the next turn in the opposite sense, all we need to do is displace our hips to the other side to sit on an imaginary stool located beside the heelpiece of the other ski. 8.- PEDALING Here, the mental relation is to bicycling. This is and ideal exercise for those who practice that sport frequently. 26

27 On a very long and smooth green run, imagine yourself riding a very wide bicycle, (almost like a motorcycle) without a seat; therefore, you are standing on the pedals which are the racing type with bindings. Pick up speed while gliding straight downhill, once you reach the required speed, start to pedal. This pedaling action must always start not by pushing one pedal and then pulling the other but by first pulling up the pedal that is lowest, followed by an extension of the other leg to push its pedal down. Think of how you move your bicycle under your body when you cycle while standing on the pedals to pick up speed; the action is similar. It is essential that you experience this exercise as pedaling, not as ski turns. It is also imperative that your feet not ever leave the ground. 9.- COMBINATION Any combination of the pedaling exercise with any of the other exercises described above is very useful. In those cases start with the other exercise and then add the pedaling action. For example, if you mix it with the tubes, first start to roll your feet over the tubes and accompany that action with a pull up of one leg an extension of the other, then another roll followed by the opposite pedaling, combining both actions alternately. Finally, for those who consider themselves expert skiers, for whom the Model of Reference is a dynamic parallel turn, I suggest the following exercises: 10.- TURNS WTH EDGE CHANGE ON THE SAME SKI On a blue or red run you are making medium size turns with your weight mostly on your outside ski. Each turn must be finished by an action where you progressively change from the inside edge to the outside edge of the same ski. You achieve this by combining a roll of the ankles and a lateral displacement of your knees downhill, accompanied by a flexion of the downhill leg. The idea is to almost start the next turn on the same ski you were pressing on before. Just at the moment that ski goes on to the wrong edge as the result of the aforementioned actions, you must actively extend the other leg (like when you pedal) which will transfer the pressure to its ski. The idea is to change edges before changing the pressure from one ski to the other TURNS WITH AN EFFORT TO MOVE THE OUTSIDE SKI TO THE MEDIAL PLANE. These turns are similar to the former ones, but you must start the action of releasing and rolling the ankle before finishing your turn. To accomplish the conclusion of the turn with your skis while you start the aforementioned actions, you must continue a rotary effort of your limbs around a vertical axis in the same sense you were turning before. This effort must continue until your skis become flat to the snow surface. The rotary action plus the knee and hip activity must be accompanied by a muscular effort to bring the outside ski to the medial plane. Just like on exercise number 10 the pressure must be transferred to the other ski after the other four 27

28 actions are executed, by means of an active and gradual extension of the new outside leg. This is undoubtedly the most difficult exercise of all because you must be capable of executing and coordinating at least four different actions simultaneously with various muscular groups; you must give in to the outside forces by un-edging with your ankles and knees, simultaneously continue turning by rotating your legs, you must flex one leg with an additional effort to bring it to the medial plane, and follow it all with a gradual but dynamic extension of the other one. On top of this, some of those actions are the active part of the turn that is ending while others are active in the preparation and execution of the next one good luck. If we analyse all the above exercises, we will notice that the whole bunch aims towards the same goal: To make our Center of Mass cross over the skis downhill with as smooth and fluid rectilinear trajectory as possible. PLEASE FORWARD ANY QUESTION OR COMMENT IN REGARDS TO THIS ARTICLE TO THE AUTHOR THROUGH THE CONTACT LINK ON THE HOME PAGE. A NOTE FROM THE AUTHOR It was as a consequence of the Canadian Ski Instructors Alliance presentation during the 1983 INTERSKI Congress at Sesto, Italy that I got the first glimpse of the fact that we were not understanding skiing as it truly is. This made me very uneasy because, if what I was perceiving was a fact, all our analysis, detection and corrections as much as the way we were teaching the sport was wrong. It was such the extent of my worry that I started an extensive investigation project, first trying to clearly understand how our sport really occurred and once that goal was achieved, creating and collecting from other sources a series of exercises that would allow me to communicate to my students the knowledge obtained from my investigation. Some of those exercises appear described on chapter 9 of this document. On September 13 of that same year, together with 27 other colleagues, we legally started the Chilean National Ski Instructors Association with the objective of organising all ski instructors, teaching courses, and increasing their professionalism and technical level. From that date on, as the elected Technical Director of the organisation, I started to integrate the results of my investigation to the manuals and text books used by the association to teach its professional courses. The year 1996, because of my professional obligations, I resigned as Technical Director, but remained as National Examiner and as member of the Technical Committee. A couple of years later I left the committee remaining only as examiner. Starting on the year 2000, as the result of major change in the Technical Committee, a large number of the technical contents I had put in the manuals were removed. Seeing year after year that the result of my extensive investigation was being lost, I decided to write and publish a small book. 28

29 Several months later, as my writings were starting to be fruitful, my wise wife Ana Luisa told me: Books belong to the past, if you really want the results of your work to reach as many people as possible throughout the world you have to publish them on the web. And on that day, which was the day of my birthday, she gave me, as a present, the web page where you just read this document. If you consider the contents of this document valuable information, you can help to spread it by sending this web page to all your skier friends. 29