9 comments

  1. Apologies…forgot to add. Your latest thinking re com movement is consistent with what I am experiencing and what I actively seek in every turn when I want to achieve cross over. That said, I actively seek the ball of the foot through lower leg activation when I want to achieve cross under – so I think your original thoughts are correct also. For pure cross over I avoid the ball of the foot and lower leg activation but for cross under I seek these things. So I think you are right on both counts, just slighty different movement priority based on desired outcomes. My only addition to your thinking is that my feet and inside arm are now connected by some sort of muscular kinetic chain – hence my question. You will see this in the slow mo clip I will send you. This is consistent for cross over and cross under.

    1. Hi Peter, as I point out in About Me, when I first set out down the road I have been on since the late ’70s, I was very much aligned with ‘the foot functions best in skiing when it is immobilized within a ski boot that perfectly mirrors the shape of the foot and leg’ narrative that not only persists but is even more entrenched today. In the early ’80s I started moving away from this position. The barefoot studies by Benno Nigg of the Human Performance Laboratory at the University of Alberta, were the first indications I got that I was headed in the right direction. In recent years, the interest in shoes that minimize their impact on foot function has begun to explode. In my recent patent,’Footwear for use in specialized activities’ WO 2013086632 A1 published on June 20, 2013,I stated: “Mono-planar surfaces are used as a standardized starting point for the plantar and heel stop elements. As will become evident, adding additional surfaces to the plantar surface of the plantar element in conjunction with controlling the maximum height of the arch of the foot can influence or ‘control’ the function of the foot and, by association, the function of the lower limb”. The effects of structures under the foot that modify the standard monoplanar surface can have profound and accummulative effects on the entire body.

      You said, “My quest has to been to find and reproduce the perfect ski turn on inline skates and record it – with the advantage of knowing exactly what I had to do to achieve it. I then take this information and try to apply it to my skiing”. The problem in skiing is that much of what is revered as wisdom is based on uninformed observation. Thus movement of the outside knee into the turn is described as ‘knee angulation’ and skiers are incorrectly advised by coaches and ski pros to “drive their knees into the turn”.

      In order for skiing to advance as a science, it requires a concentrated and concerted effort by to acquire a comprehensive understanding of the mechanics biomechanics and physics. I am always interested in the efforts of those such as yourself. I will arrange to see your videos.

      “My only addition to your thinking is that my feet and inside arm are now connected by some sort of muscular kinetic chain”. I agree. There is also an influence of the stance and swing legs that occurs in the transition phase.

  2. Hi David, thank you so much for such a detailed reply.

    I think that not only are you on the right track but I may be able to help advance our collective understanding. For the past three years – and further to being dissallusioned by the contradictory information I got from my association (full disclosure, I am a disallusioned PSIA level 2) – I have been experimenting in a controlled environment with inline skates and testing the veracity of the various movement patterns I find in information publically available. My quest has to been to find and reproduce the perfect ski turn on inline skates and record it – with the advantage of knowing exactly what I had to do to achieve it. I then take this information and try to apply it to my skiing – although that is another story.

    After 3 years of practicing on skates for at least an hour a day, when weather permits, I am getting close. You will be pleased but not surprised to know that your worldview has consistently proved to be correct – in my laboratory at least.

    But here is the rub. Recently, and after reading and trying to replicate the movements in your recent blog on Shiffrin, my skate experimentation indicated a strong correlation between an active rotation of the humerus with the action of ‘getting over it’. It is still early days in the exploration but the quality of my turns has seen a step change in improvement. If you are interested I have some sequencies taken today with coaches eye that I would like to share with you. Although this is not skiing, and inline skates allow for a much greater range of ankle movement (although I inhibit that movement to the extent necessay to maintain the restive angle) I think you will be surprised by the resemblence to high end ski movements.

    Happy to explore this further with you.

    Best Regards
    Peter

  3. Hi David, I thoroughly enjoy your articles and find they provide thoughtful and insightful information. Your blog has helped me develop and refine the movements I use in my own skiing and dryland inline skating. Concerning that development, I would be interested in your thoughts on the role the anterior oblique subsystem of movement (AOS) plays in roll over. As I refine the foot movements you describe, the more this system seems to make itself evident. I am now at the point where rotation of the humerus of the inside arm appears to coordinate the action of roll over. I am yet to determine if this is this real or an imaginary personal cue.

    1. Hi Peter, the anterior obliques do play a role in role over. But I am still trying to understand how they work with the other elements.

      The deceptively simple act of walking uses half of the body’s 650 muscles. At the end of a turn, the muscles in what will become the new supportive column (the outside leg) of the new turn has to be activated. This is the very thing that the modern ski boot and interventions such as supportive insoles and tightly fitting form fit liners and, in recent years, booyt shells, are intentionally preventing. Last ski season, I had a major breakthrough with my own skiing and other skiers I was working with by reducing the ramp angle to about 2.5 degrees from 3.0 degrees or more. I have since found studies that show that any amount of elevation of the heel relative to the forefoot has an adverse effect on the function entire body, that causes, among other things, a shortening of the Achilles tendon and a shift in pelvic orientation. The question I am now trying to resolve is after the lower limbs have been rehabilitated from the damage caused by traditional shoes, is the ideal ramp angle for skiing zero?

      In response to your question about the tole of the humerous of the inside arm, when I started this blog I was of the opinion that it was essential to get COM positoned over the ball of the uphill foot (new outside foot) in the traverse component of the transition. My current thinking is that the key is to use the momentum of COM to transfer the load to the inside foot to activate the bottom up elements of the column so as to be able to control the ski and maneuver it into alignment with COM in the fall line before crossing over into the bottom of the turn. Done correctly, a turn becomes a reflex movement similar to walking that only requires an initiating ‘trigger’ or pulse on the new outside leg in the transition. All of this needs to happen very rapidly in a bottom-up process that starts in the foot. The actual biomechanics are a work in progress.

  4. Hi Dave, intrigued by your most recent articles with Matt (liner adjustments) and ramp angle.

    Do you think starting with binding ramp is a good place to explore adjustments to stance? I’ve just adjusted my Rossi Pursuits in line with my Rossi GS skis – 3mm difference from heel to toe.

    I also have a pair of Head Raptor 130’s, same as Matt. I’ve got my hands on a few pairs of zeppas and have removed 1mm from the heel to lesson the ramp, on one pair. Gonna test this as well.

    Thanks,
    Jay

    1. Hi Jay, based on recent breakthrough results from reducing ramp angle in my own and my wife’s boots and feed back I have received from followers of my blog, I now believe that ramp angle is the single most significant and most overlooked aspect of skiing. A three mm difference is significant. Michael has some issues on bindings that expand on those that I have raised. If you are able to shim the bindings to zero ramp, I would start there. I have been told that Head recreational skis have zero ramp bindings. I am following up on this.

      I am about to post on a third generation Stance Ramp. This version does not use a fixed angle. Instead, it relies on the perception of the user to find the best ramp angle. The human brain adapts transparently to changes in terrain that could cause a fall. Something as simple as raising an arm shifts the location of CoM. The brain adjusts so transparently that we have no conscious sense it has happened. The same thing happens in ski boots. If ramp angle is excessive, the brain will shift the weight to the heels for security. This quickly becomes the default or ‘normal’ position on skis because to the brain, it is the best balance solution. If you try to override it by altering stance, the brain will reconfigure CoM.

      You have to learn the elements of a strong stance before you can find the ramp angle that optimizes it. One thing I will talk about soon is the advantage of screwing the boot board to the bottom of the shell. The Head Raptor boot board is suitable for this.

  5. I am still working to really understand all that you have written here, but I am very intrigued. One thought that came to mind regarding the movement of the ankle and foot in regards to balance would be to try to do various balance exercises (slack line, standing on swiss bal, etc.) in ski boots. Thoughts? Past experiences…?

    1. Trying to do balance exercises wearing ski boots on mediums like a slack line or a Swiss ball would be dangerous and not helpful to developing balance. There seems to be a disconnect in skiing between the physical environment that exists when standing in ski boots on a solid floor in a ski shop where adjustments are typically assessed and the physical environment that exists when a ski is on edge and the external forces are complex and dynamic. These environments are often treated as if they are the same. They aren’t by any stretch of the imagination. In order to ‘stand’ on the outside ski of a turn, a skier must first set up a platform characterized by a continuous source of (ground) reaction force under the foot. This requires a specific alignment of opposing forces that can only be set up when the base of the new outside ski is ‘flat’ on the snow surface. This cannot be done when a ski is on edge or when an unweighted ski is weighted on edge. The fact the I have been unable to find any discussions of the forces acting across the inside edge of the outside ski (what I call ‘ground zero), suggests to me that either no one understands the real issues or for some reason they do not want to discuss them. Putting all the forces acting across the inside edge introduces a whole lot of factors that have a profound effect on skier performance that are currently not being addressed. I raised the issue of SKI LEVERS in a previous post. The critical aspect of forces acting across the inside edge of the outside ski is the Inside Edge – Load Transfer Axis. It is the position of the Axis that determines whether a skier can set up a platform under the outside foot and especially the point at which the external forces exceed the limits of internally generated forces that affect ski and edge control.

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