By Dick Taylor
Published: Mon Jun 02, 2008 5:18 AM MDT
Updated: Mon Jun 02, 2008 2:02 PM MDT
Dick Taylor presents some some very interesting and potentially controversial ideas about skate technique, especially in relation to the current conventional wisdom. Feel free to discuss Dick's ideas using the comment form at the end of the article. Please keep comments on topic and related to the article content.
Jack Sassvilles article in Master Skier, Skating and Weight Shift(p.5), needs to be continued. His second-to-last paragraph is a good place to start. With the increased emphasis by many coaches and instructors on facing forward and not twisting, it has become harder for many skiers to skate with a complete weight shift. They are stuck between their skis and spend most of their time on two skis, one against the other. Skiing on one ski will make you as better skier.
How complete weight shift and the resulting optimal glide on each single ski fell out of fashion has totally baffled me. When I look into the history of skating I do find some reasons, but they never have represented sound thinking or biomechanical principle (even among some biomechanists, as I will point out). Too often in our sport writers have a stronger urge to be in the know than to draw conclusions from actual research and patient examination. Athletes often abet this tendency by presuming mastery before they have it. As I have noted before: athletes are flowers, coaches are gardeners.
Maybe some of the differing views originated in the usual way. It was natural that as skating began the initial theories were based on the observations and experiences of both coaches and the innovative spirits of athletes. Trial and error was ever present. It did not take long to figure out that even in marathon skating, for example, the most powerful push with the poles came by squaring the shoulders to the skating ski. We watched the top Europeans, and they were doing it that way. As V1 came along, the same squared shoulders seemed logical, except that one early prescription was to lead the shift from ski to ski with the shoulders, and that caused both excessive motion and, more critically, an inward rotation of the body during the poling. Another result was the twist that rotation caused in the push-off leg and a kinking of the knee, which caused the shoulder to drop, the hip to move in and the ski to prematurely edge. One cause of this twisting may well have been that the skiers simply were not strong enough in the legs to stay directed over the gliding ski through a complete push-off to the other side. They rotated inward from the axis of glide instinctively to escape the demands of kicking from that position with complete spring. In 1986 at races in Calgary one top USST skier admitted that generating that much power per kick was just too much for him to sustain. So he continued rotating inwards, smoothly to be sure, to avoid the too energy-expensive kick.
Sensing that was ineffective, one solution was to square the shoulders/pelvis more forward in order to trim up the movement. Another, and better one, was to recognize that the weight shift was initiated from the foot up, not the shoulders, and the whole body went back and forth efficiently, without the active rotation. This also preserved the optimal pushing with the poles in a plane parallel to the gliding ski all the way through the motion.
The skating studies done at Penn State documented this among the better skiers. Unfortunately, the authors went beyond their knowledge of descriptive biomechanics to prescriptive movement theory and made a fundamental conceptual mistake. That takes a little explanation.
Two studies were completed, one in 1986, another in 1989. Based upon their three-dimensional high-speed photography and the stick figures constituted from it, several mechanical implications based on observations were noted. I will use two as examples.
Since the pole angles, while planted in the snow, are good indicators of the direction of force application provided by the pole, poles angled in the direction of the ski glide may have a greater proportion of the resultant force applied in the direction of ski displacement. This direction of force application by Svan and a number of the faster skiers suggests the objective of forces applied by the poles is to accelerate the skis in the direction of the ski glide angle.(p.11, 1986)
This is simple physics, and it suggests the rationale for squaring the shoulders to the direction of the gliding ski as the most effective way to gain greater acceleration from poling. Later in the study (p.48) the upper body is more generally added to the equation: A greater flexion of the trunk can perhaps generate greater poling thrust and greater stride length.
Immediately following the observation about poling angles (p.11) the authors make the next point. Since the path of the head closely follows the path of the CM [center of mass], the head position of the skier can be used to estimate the CM location when viewing skiers in the field. Perhaps instructions to the skier suggesting less lateral deviations of the head from the line of travel may assist in keeping the CM from deviating unnecessarily from the line of travel. A later conclusion follows (p.48): The faster skiers had velocity vector angles directed more nearly up the track than did the slower skiers. Thus it is important that CM motion not be directed along the ski glide direction but rather aimed in the track dimension, as much as possible.
This suggested implication is based upon the observation that although the path of the CM was in the shape of a corkscrew throughout, the faster skier showed less lateral deviation from the line of travel, at that time, meaning straight up the trail. In other words, if you want to go faster, which is also to say more efficiently, sway back and forth as little as possible. This is the conceptual mistake: It is a confusion of cause and effect. The correct explanation for their observations should be: If you go faster, your deviation from the line of travel will naturally be smaller. Speed begets position; simply putting yourself in the speed position does not beget speed. The movement in its environment (speed, snow type, incline) determines the skier's motor options; he can no more simply set his position beforehand any more than a sailor can decide beforehand how he will set his sails. Secondly, since the path of the CM is corkscrew-like, by the very nature of the movement, it is in fact necessary to deviate from the line of travel to propel yourself at all.
This is where skating gets fishy. A fish does not propel itself with its fins working from a straight body but with the back and forth of its whole body against the flow of water. If the stream speeds up, the fish speeds up the back and forth motion and the deviation from a fictional straight line direction of travel diminishes. I have used this image with skiers for many years and found it helpful to them. Since the World Cup in Biwabik, Minnesota can be downloaded from YouTube (search Biwabik), one can study the differences. Another image comes to mind: sculling a boat with one oar through an oarlock on the transom. You have to push the oar back and forth in order to move the boat forward, and the more the whole body pushes back and forth, the more forceful the sculling motion will be, until it achieves a level of speed, at which point the sweep decreases.
From the beginning of skating I cannot remember ever finding any sense in facing straight up the trail. Since it was a form of double-poling, it made sense to me as one-legged double-poling. I could not think otherwise when I saw Ove Aunli and Oddvar Bra teaching themselves to skate on the Dachstein Glacier. I was below them, so I could not see their skis. They looked to me quite simply as if they were doing a double-pole session.
Interestingly, the 1989 study following analyses of the Calgary Olympic events contained several changes of perspective. Now Increased lateral motion of CM tended to increase CL [cycle length] while decrease CR [cycle rate].(p. 1). Thus lateral motion is part of the skier's variety of tactics, or solutions, as people in motor learning refer to them. Also, the direction of the strong side…was faced by the shoulders and trunk through much of the cycle. The skier of Figure 6A displayed a somewhat more balanced orientation than did the skier in Figure 6B. The latter's body orientation was directed primarily toward the strong side even during much of the weak side skating phase. (p.11)
Unfortunately, the straight up the trail school of thought apparently did not digest this second study, or elementary biomechanics. With a lot of intelligent young skiers coming into skating, experimentation was in the air. Recently I received an illuminating letter from a fellow coach describing that time:
I started skiing just as classic was departing. During my first few years of racing, we went from marathon skate to V1 to V2 in basically two and a half seasons. By the time we got to V2, the Koch-inspired big movements were already going away and a more static face down the trail style was arriving. I clearly remember [their coach] and the guys on the Bates Ski Team teaching me V2 and really emphasizing facing your ski tip with big, swinging movements. When I watched Pierre Harvey, Gunde Svan, Dan Simoneau, and especially a young Ian Harvey, I saw much less exaggerated movements. Within three weeks of learning V2, I was reducing the amount of twist I had been taught. Within 4 weeks, I was beating guys I'd never been close to - including all but one of the Bates Team. That pretty much hooked me on working in the direction of travel (although I didn't think that much about it at age 16).
By the time I had settled into the ski team at [college] my sophomore year (1990) and [coach] came along, we were watching the upcoming Norwegians, instead of the Italians ands Swedes. [Our coach] really did a fair amount of work on technique with slides, etc. But all of us on the team thought the stuff was antiquated. We watched video and each other - perhaps too much. One of my best teammates and I often had class schedules that conflicted with team practice, so we trained on our own, together. We were of the same build, and also felt that Torgny Mogren was the best model for us, as he was efficient and of our build. We began to work hard on deeper knee bend than we'd been taught, especially on uphills, and a more upright position on the flats. By our senior year, we both broke into the top 10 in Eastern Collegiate Carnivals - really a huge achievement for me, as I hadn't been able to make the women's team in my first year at school. I was totally sold on choosing technique that matched your build/abilities.
When I began coaching, fresh out of college, NENSA was just starting up, and [coach] was having his way with technique development in New England. [He] is a good thinker, and he and I spent a good deal of time talking technique. His take was that you wanted to be dead square to the trail with a lot of turn out at the hips. I think I got suckered in with everyone else. The U.S. Ski Team, and most of the Eastern College coaches, began preaching the same thing. Still are. Just watch our top distance skaters-which might explain their skate results.
I didn't get away from this until I moved north and began working in relative isolation again…long-winded, I know. But the answer to your question [Where did facing up the trail come from?] is two-fold: facing up the trail came from [coach], and then from the USST. It was backed up by a technique video from the Norwegian Ski Federation that studied Daehlie, Alsgaard and others. For some reason, the consensus at the time was that Daehlie was winning with a combination of technique and engine. Alsgaard was winning purely on technique, and that Fauner and Valbusa were losing because of technique. In retrospect, it would seem that Daehlie may have been winning despite technique [he himself said he was trying to copy Alsgaard in order to improve], Alsgaard likely has a bigger engine than anyone suspected, and that Valbusa may really have been doing something right.
A history of our thinking by intelligent athletes like this is enormously useful in giving us all a clearer grasp of how we have come to think the way we do. There is genuine curiosity and critique here, which should be clearly understood as distinct from criticism. Enthusiasm, irrepressible fascination, and well-wishing have always glued our common motives together, and should keep us humble, collaborative, intellectually disciplined, and, above all, wary of the attractions to gurudom, both in ourselves and others.
I have left out names because they are not the point; it is the dynamics of the thought process which matters, and its decisive affect on our young skiers. You can hear vocabulary which has been used in the past in the words, and movements of a subsequent athlete or coach. But the coaches and instructors whom Jack mentions at the end of his article simply can no longer justify the baseless prescriptions contained in, among others presentations, the PSIA Manual, in which it states:
Advance skate skiers move their core straight down the track as much as possible while skating from one ski to the other. A beginner tends to move the core from side to side with each skate. When analyzing the core of the skate skier, try watching from behind. If the core is moving from side to side, or waving from one direction to the next, have the student concentrate on keeping the hips and torso always facing in a straight line. Thus the origin of the neutral position.
As I say, names are not the point, and the above view is not wrong because I happen to think so. It is wrong from the point of view of the best science, biomechanics, motor learning theory, and the educated analyses of Europe's best coaches, and not because they are Europeans but because their science is more thorough and thus more compelling. It also allows for variance in the expression of the operant principles of biomechanics and motor learning among individual athletes, but the principles are there, like a basic grammar of movement just like the grammar of a given language. Without knowledge of its grammar, we are ill equipped to accurately perceive what we hear in another tongue. Without extensive biomechanics we are ill equipped to accurately see and describe what we are looking at. That becomes particularly clear when we recognize that the duration of the kick in classic is from .1-.2 seconds and in skating .3-.8 seconds. How can we describe a movement which is the speed of an eye blink? Your eyes or my eyes cannot see that fast on their own and will therefore miss the swiftest critical movements.
I have spent a lot of time over the years looking for help. Some of my thinking is buttressed by years of very high-quality articles in the German Nordic Sports Magazin, ongoing study of all available materials relating to the German program, including relevant articles from IAT (Germany's Institute for Applied Training Science), Das grosse Buch vom Skilanglauf by Hottenrott & Urban (Meyer&Meyer, Aachen, 2004), a true reference manual for the German program, and a recent comprehensive study of the history and current state of skating research, Biomechanische Analysen von Skatingtechniken im Skilanglauf, by Stefan Lindinger, (Meyer&Meyer Verlag, Aachen, 2006), 300 pp.
In not a single instance have I encountered the suggestion of facing up the trail, to the contrary, the universal prescription is rechtwinklig zur Gleitrichtung, right angles to direction of glide. In a series of technique presentations in Nordic Sports Magazin Marco Selle, the coach of the Italian National Team analyses first Tor Arne Hetland's V2 and in another Virpi Kuitunen's classic and skating. About Hetland he notes, among other things, shoulders in direction of gliding ski, support the pelvis movement and stabilize the course of the movement. From the foot to the shoulder joint there is a line. Pressure always on one ski. The weight transfer from one ski to the other is always harmonious, almost dancelike. He never loads both skis at the same time, yet the movement is absolutely flowing. Hetland always brings his body weight optimally over the ski. Thus his power can unfold optimally and glide cleanly. Selle also uses the term direction of travel, but it is clear he does not mean the line of travel but rather the path the body must travel, back and forth, with greater or less lateral movement depending on speed and terrain, like the fish in faster or slower water. In other words, direction of travel is to be understood graphically as a broad arrow within the walls of which the skier goes back and forth. Obviously, we cannot change the trail, but speed and terrain variables teach us to make the trail wider or narrower as, like the fish, we go upstream.
Of Kuitunen he notes that her V1 is quite good. High position, which allows the legs to operate closely together. [USST wide stance prescription The USST talks about saddle feet in a techinique video] The shoulders are parallel [facing] to the ski set on the snow. Different than her rivals, she is in a position to shift the shoulders and pelvis to the opposite ski not until the second push phase of the arms…which brings stability and efficiency. Of Pietro Piller Cotter's V2 he says similar things: He is always compact, with the limbs in a line, very high and narrow in his execution…His shoulders are always oriented toward to ski tips. A YouTube search for Alsgaard going from V2 to V1 demonstrates the same point (made also in the 1989 Skating Study for skier B, see above).
Her V2 and V2 alternate on the flats (long glide phase) is not optimal. Even when she succeeds in having good ski directionality through her balance and good ankle work, one can see how she has problems with bringing the pelvis/hips into an axis with leg and upper body. This results in the knee rotating inward. Thus the shoulders and pelvis work parallel [facing] to the opposite ski rather than the ski on the snow. This results in several problems: it is not possible to reach a stable and relaxed position; also gliding on the inner edge of the ski. This makes the push-off less efficient.
I am hoping to receive permission to incorporate the excellent sequence photographs from these articles into an article of my own. For the moment, however, I think the case for facing the direction of glide is both compelling and urgent if we intend to serve our skiers with integrity as informed professional coaches. Read the rest of this entry »
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