Zeppa-Delta

TRANSITIONING FROM FIT TO HIGH PERFORMANCE FUNCTION


That footwear can negatively impact the physiologic function of the user has been known for many decades. But the issue of the effect of footwear on athletic performance came into sharp focus in 1987 with the publication of the medical textbook, The Shoe in Sport (published German in 1987 as Der Schu im Sport). The Shoe in Sport brought together the collective expertise of 44 international authorities on orthopedics and biomechanics to focus their attention on the SHOE PROBLEM in the context of problems shoes can cause for athletes in terms of compromising performance and contributing to injury. The Shoe in Sport focusses on the medical orthopedic criteria in offering guidelines for the design of shoes for specific athletic activities including skiing and ice skating.

In the Introduction to the Shoe in Sport, Dr. med. B. Segesser and Prof. Dr. med. W, Pforringer state that the findings in the textbook should enable the interested reader to distinguish between hucksterism and humbug on the one side and the scientifically sound improvements in the athletic shoe on the other. The Shoe in Sport made it abundantly clear that it is not a question of if structures of footwear will affect the physiologic function of the user, it is a question of how structures of footwear will affect the physiologic function of the user and especially whether they will compromise athletic performance and/or contribute to injury.

With regard to guidelines for ski boots, the international authorities on orthopedics and biomechanics who contributed their expertise and knowledge to Part IV The Ski Boot took the position that, among a number of other things:

  • ………. the total immobilization by foam injection or compression by tight buckles are unphysiologic.
  • The ski boot and it’s shaft must be adapted to the technical skill of the skier, and the technical skills of the skier must be adapted to the preexisting biomechanical functions of the leg and the foot.
  • It (the design) should not make compromises at the expense of other joints ………
  • It (the ski boot) must represent the ideal connecting link between man and ski (steering and feedback).

The position of international authorities on orthopedics and biomechanics on the medical and biomechanical criteria for ski boots was succinct, concise and unequivocal:

…….total immobilization by foam injection (implying by any means) or compression (of the foot) by tight buckles are (both) unphysiologic.

Dr. E. Stussi,  Member of GOTS and Chief of the Biomechanical Laboratory ETH, Zurich, Switzerland made a prescient statement with implications for the future of knee injuries in skiing:

Improvements in the load acting on the ankle (implying load from improved fit) make it biomechanically very likely that the problems arising in the rather delicate knee joint will increase.

While the international authorities on orthopedics and biomechanics who contributed to The Shoe in Sport provided valuable guidelines for the design of the ski boot they did not offer a specification that would assist designers and those who work with ski boots in meeting the medical and biomechanical criteria in the guidelines. My hope and intent was that the Birdcage studies and the content of my US Patent 5,365,350 (issued on 11-30-1993, expired on 12-28-2005) would serve as a foundation on which to build a specification that would enable the structures of ski boots to be adjusted to accommodate the personal functional requirements of the skier.

The steps in my transition from Fit to High Performance Function

After the unprecedented success of my dorsal loading invention with Crazy Canuck, Steve Podborski, I used the same system with similar success in the boots of a small number of other racers. I also incorporated this system into my own and my spouses’ ski boots in conjunction with suitable liner modifications and a reduction of the ramp angle of the boot boards to just under 3 degrees which I had identified in about 1978 as the maximum angle for skier performance. (NOTE: Since I wrote this post I have reduced the delta angle of my Head boots in stages with improvements in performance. It is currently close to zero.)

I can’t recall exactly when, but about 20 years ago I decided to move away from Lange ski boots. I purchased a pair Head World Cup 335 mm ski boots for myself and a pair of Head X-80 295 mm ski boots for my spouse. I say built because to me ski boots are raw material.

I had to completely disassemble the Head X-80s and drastically modify and reconfigure the components to adapt them to the morphology of my spouses’ feet and legs. The process took me about 35 hours. I was able to modify my Head World Cup liners to make them work without the same degree of modification. I made a dorsal loading system for my spouse similar to the one I made for Steve Podborski’s Lange ski boots.  But I was able to modify the existing Head tongue so it would adequately load the dorsum of my foot. The reason I went this route is that the shell of my Head World Cup boot is very stiff. This makes inserting my size 12 US men’s foot and a dorsal system, like I fabricated for my spouse, challenging. In the order of things the dorsal system is inserted after inserting the foot in the shell.

The photo below shows my Head liner after initial modifications.

The photo below shows the Lange tricot liner I used in my spouses’ Head boots on the left with no modification other than removing the Lange flow fit pads in the side pockets. I was unable sufficiently modify the liner that came with her Head X-80 boot. The version on the right in the photo below is the same liner after modifications i made for it work with the dorsal system shown in the photo underneath. The dorsal system in itself took many hours of painstaking effort to fabricate and fine tune.

With our modified Head boots fit with my dorsal loading technology my spouse and I would easily be classified as expert skiers. As recreational skiers with skiing limited to 10-15 days a season, most skiers would have no incentive to question the adequacy of their boots or especially devote time and effort towards finding ways to reach a higher level of performance. To the contrary, I found it disturbing that the ability to ski better than the majority of skiers fostered an intoxicating sense of superiority. But I knew what I didn’t know and I knew that I still had a lot to learn. In my mind, the transition required to realise our full performance potential was not yet complete.  I knew that the potential for improvement has no boundaries.

The transition to High Performance Function continues In my next post……….

TRANSITIONING TO A HIGHER LEVEL OF SKIER PERFORMANCE

The transition to a higher level of skier performance for my spouse and I started in the 2012-13 ski season. After a ten-year hiatus from skiing we were returning to the ski hills with renewed enthusiasm coupled with a desire to reach a higher level of performance. I purchased new narrow waisted skis for both of us. I intended to purchase new ski boots as well. But I quickly backed off from even considering this after assessing a number of new boots as too difficult to work with.

I started The Skier’s Manifesto in the spring of 2013 for a number of reasons. The primary reason was that the forum provided me with an opportunity to acquire new information and increase my knowledge so I could learn how to transition my spouse and I to a higher level of skier performance. The process of attempting to explain complex technical issues by writing articles and posts serves as the impetus for me to think deeply, thoroughly and analytically. As the process unfolded, I discovered issues I had overlooked in the past or not fully explored.

One issue I had not fully explored, let alone addressed, is a way of identifying the optimal ramp angle specific to each skier. Ramp angle is the angle of the ramp of the plantar plane under a skier’s foot with the base plane of the ski. Finding a method of identifying optimal ramp angle proved far more difficult than I had anticipated. But when I succeeded in identifying and then implementing the optimal ramp angles for my spouse and I last ski season this proved to be the gateway to a higher level of skier performance than I could ever have envisioned. After identifying and then confirming my optimal ramp angle as 1.2 degrees (bindings zero) I finally understood after almost 45 years how and why changing from the leather ski boots I learned to ski in to the new plastic boots had such a devastating impact on my skiing. It was the change in ramp angle. The ramp angle in my leather boots was much less than the ramp angle in my plastic boots.

NOTE: Since I published this post a little over a year ago I have since reduced the zeppa angle of ,my Head boots to close to zero)/

By 1978 I had subjectively found that a ramp angle greater than 3 degrees adversely affects skier performance with some skiers affected more than others. I knew there was no one size fits all, only that more than 3 degrees seemed to cause problems. From 1978 onward I was improving skier performance by ensuring the total ramp angle of the combined boot board/binding (zeppa + delta) was about 3 degrees. For females with small feet this required grinding the boot board in Lange boots flat or even negative (heel down) to compensate for binding ramp angle which increased as the toe and heel pieces moved closer together for small boots. I wasn’t always able to get the ramp angle set at 3 degrees. But getting it in the 3 degree range consistently resulted in significant improvement in skier performance.

It was becoming increasingly apparent to me that finding the optimal individual ramp was critical.

Critical Ramp Angle

In 2018 I identified the critical ramp angle as the angle of the plantar plane in relation to the base plane of the ski that enables a skier to apply maximum vertical force to the ball of the outside foot when the COM in the pelvis is stacked vertically over the head of the first metatarsal.

The vertical force is applied passively by force transfered to the plantar aponeurosis ligament (PA) by Achilles tendon (AT) tension.  As COM moves forward towards the head of the first metatarsal in the support phase where skier resists the force of gravity, AT-PA tension applies an increasingly greater down force to the head of the first metatarsal. Ramp angle is optimal when the vertical force peaks just prior to the end of the support phase in what is called Mid Stance in the Gait Cycle of walking.  I qualified this mechanism as enabling a skier to apply maximum vertical force to the head of the first metatarsal. Studies have shown in the skiing the position of the pelvis in relation to its vertical position with foot is the most reliable indicator of the position of COM. A skier is able to control the vertical force applied to the head of the first metatarsal by controlling the position of the pelvis.

The photos below show Marcel Hirscher and Tesa Worley applying maximum force to the head of the first metatarsal of their outside foot by stacking their pelvis over it.

The Problem with Adapting

The primary determinant of the critical ramp angle is the length of skier’s Achilles tendon (AT).

The length of the AT can and does vary significantly among the general and skier populations. The type of everyday footwear worn and especially what is called drop (heel elevated above the forefoot) can affect the length of Achilles tendon.

Drop affects the timing of the process that stiffens the foot transforming it into a rigid lever for propulsion. Over time, the predominate wearing of footwear with significant drop can cause the AT to shorten as a way for the body to adjust the timing of the stiffening process. In activities such as walking and standing, a shortened Achilles tendon may not have a noticeable affect on performance. But in skiing, the timing of the AT-PA tensioning process is critical. Those who learned to ski in boots with ramp angles close to optimal for the length of their Achilles tendon typically excel at skiing regardless of athletic prowess while gifted athletes who learned to ski in boots with sub optimal ramp angle can struggle in spite of innate athletic ability. For a racer whose equipment is close to their critical ramp angle a change in equipment that significantly changes ramp angle can be fatal to a promising career.

Most skiers would assume that they can just adapt to a sub optimal ramp angle. But adaptation is precisely the reason why skiers and racers with a sub optimal ramp angle reach a threshold from which they cannot advance. When their brain makes repeated attempts to apply force to the head of the first metatarsal without success it starts to make adjustments in what are called synaptic connections to create a new movement pattern to adapt to sub optimal ramp angle. The more the equipment with a sub optimal ramp angle is used the more the associated synaptic connections are strengthened and reinforced. Once the movement pattern associated with sub optimal ramp angle is hardened,  optimal ramp angle is likely to be perceived by the brain as wrong. Telling a racer with sub optimal ramp angle to get forward or get over it (what that means) will only make matters worse because a sub optimal ramp angle makes it impossible. Correcting the ramp angle and/or the length of the AT will not help because neither will change the hard-wired movement pattern in the brain. Deleting a bad movement program can be done. But it usually takes a structured program and a protracted effort.

Mid Stance Misinformation

A factor that I believe may have contributed to the critical ramp angle issue being overlooked is misinformation about mid stance. The story used to sell footbeds and even some orthotics is that skiing is a Mid Stance activity and in Mid Stance the foot is pronated and weak necessitating a foundation under the arch to support it. While it is true that the load phase of skiing occurs in Mid Stance the statement that the foot is weak is only partially true because it doesn’t encompass the whole picture.

The Stance or Support Phase of what is called the Gait Cycle of walking consists of four phases:

  1. Loading Response
  2. Mid Stance
  3. Terminal Stance
  4. Pre-Swing

All four phases happen in a ski turn sequence. The support phase, where one foot is flat on the ground and the leg is supporting the weight of COM, is called Mid Stance. The position of COM in relation to the head of the first metatarsal in Mid Stance and how fast COM can move forward over the head of the first metatarsal (center of the ski) of the outside foot in the load phase is a major factor in dynamic control and the ability of a skier to apply maximum force to head of the first metatarsal. But Mid Stance is a range and a sequential stiffening process, not a fixed point as has been misrepresented for decades by many in the ski industry.

The graphic below shows the relationship of 1. Achilles Tendon Force with 2. Plantar Aponeurosis Force with 3. Vertical GRF and how the tensioning process and transfer of force to the head of the first metatarsal occurs as COM progress forward in the Mid Stance cycle. The timing of the forward advance of COM/Pelvis to sync with peak AT-PA force transfer to the head of the first metatarsal is shown with a red circle and vertical arrow.

If I had only shown the segment of Mid Stance in the grey rectangle at the beginning of Mid Stance on the left I could have made a case that the arch is weak and in need of support since Achilles Tension is zero and Plantar Aponeurosis Force (called strain) is very low. But this would be misinformation because it does not show the whole picture. If the foot were weak as is alleged it would be impossible for it to act in the capacity of a lever in propelling the weight of the body forward in locomotion.

In my next post I will explain how I used NABOSO surface science technology to confirm my optimal ramp angle.

 

ZEPPA-DELTA ANGLE EXTENDER

The problem associated with measuring boot board (zeppa) and/or binding (delta) ramp angle as individual components is that the resulting angle may not accurately reflect the actual angle between the plane of the base of the upper surface of the boot board and the base of the ski in the boot/binding/ski system. Boot boards of the same zeppa angle may not necessarily have the same zeppa angle with the base of the boot shell due to design and/or manufacturing variances.

A level inserted into a ski boot shell with the boot board in place can be difficult to read. With the liner in place, this is not a viable option. A better option is to extend the angle of the boot board up above the top of the shaft of the boot so it can be accurately and easily read.

A simple device for this purpose can be made for about $25 with basic hand tools and a few screws using 2 – 8 in (20 cm) x 12 in (30 cm) x 1/8 in (3 mm) thick steel carpenter’s squares.

Place the long arms of the squares over each other as shown in the photo below and clamp them securely together. Two-sided tape can be used to help secure the alignment. Then drill a hole  at one point on the vertical leg and screw the 2 squares together.

Check the parallelness of the 2 opposite arms on a level surface with a digital level. If good, secure the 2 levels together with a second screw. Then affix a section of 3/4 in (2 cm) x 3/4 in (2 cm) square or L-bar bar on the top of the extender to rest the level on.

To use the extender, place a boot shell on a hard, flat, level surface. If the surface is not level it should be leveled before the extender is used.

The photo below shows the extender being used to measure the zeppa angle of an old Salomon SX-90 shell. I didn’t have the electronic level for the photo. So I used a small torpedo level.

Insert the lower arm of the device into the shell as shown in the right hand image and place the lower arm firmly on the boot board. Place the level on the top arm and read the angle.

The photo below shows the same process as above. But in this example, the liner is in place. If an insole is in the liner, it should be flat with no arch form. I highlighted the square bar with pink to make it easily visible.

A check of the zeppa-delta angle of the boot-binding-ski system can be done by mounting the boot in the binding of the ski that is part of the system and clamping the ski to a flat surface with sufficient force to ensure the camber is removed and the running surface of the base is in full contact with the supporting surface. A strap wrapped over the front of the boot shell and under and around the supporting surface then tensioned will help ensure that the toe plate of the binding is loaded.

The Zeppa-Delta Angle Extender provides the user with a fast accurate way to know their total number. What’s yours?

 

RAMPING UP THE POWER OF YOUR STANCE

Note to the reader

The post that follows was originally published on March 1, 2016. At the time that I wrote it, I was trying to identify the optimal net (total) ramp angle or NRA using fixed angle ramps. But I found the process to be inconclusive for reasons I give in my recent posts on the dynamic ramp assessment device. I am reposting this older post because many of the concepts expressed are even more relevant in view of the results seen with the dynamic ramp assessment device and boot boards altered to the same ramp angle identified in dynamic testing.


RAMPING UP THE POWER OF YOUR STANCE

The foundation of a strong technique is a strong stance. But what makes a strong stance? The angle of the combined ramps of the binding and boot board or zeppa in relation to the base of the ski. If the net ramp angle weren’t important, binding and boot makers would make their products with no ramp. If ramp angle doesn’t make a difference, why bother? But not only does net ramp angle make a difference, it has a significant effect on stance.  Stance affects balance and muscle power, especially the ability of eccentric gastrocnemius-soleus complex muscle contraction to absorb shocks that would otherwise be transmitted up the leg to the knees and back. I discussed some of these issues in WHAT’S YOUR ANGLE? – : https://skimoves.me/2014/03/29/ski-boots-whats-your-angle/ ‎

If there were a problem, and there is, the ski industry is all over the place especially when in comes to binding ramp. There doesn’t appear to be any industry standards and especially any continuity between products. Worse, most skiers assume that their ski boots are putting them in the optimal stance. Without a reference they have no way of knowing. The Stance Ramp can give them that reference especially when it comes to how much ramp is enough, how much ramp is too much and how much ramp is too little.

Note Added March 19, 2018 – Having a kinesthetic sense of a stance based on tensegrity gives a skier a valuable tool that when used in a structured process can help them assess the effect of zeppa-delta ramp angle and the constraint imposed on their feet and legs by the structures of a ski boot.

In 1978, when I was building boots for female racers with small feet, I noticed that they were skiing like they were wearing high heel shoes. When I started checking their bindings and boot board ramps, I found out why. Some had 10 or 12 degrees or more of net ramp angle. After I started doing stance training with racers on a ramped board I discovered through empirical experiments that about 3 degrees of ramp angle seemed to give skiers the strongest stance.

Note Added March 19, 2018 – It now appears as if 3 degrees is the upper limit of the zone of stability. This explains why skiers started to ski better when the net ramp angle approached 3 degrees.

I didn’t really understand why until much later. Was the process scientific? No, not at all. Do studies of this critical issue need to be done? Absolutely. If I figured out that ramp angle was a critical issue almost 40 years ago, why is it that no studies appear to have done in the intervening years to determine the affects of ramp angle and identity the optimal angle?

With input from skiers in different parts of the world over the past two years, I have narrowed the ideal ramp angle down to about 2.7 degrees. This seems to be something of a standard in World Cup. Through experiments over the past few months, I have found that changes of 0.1 degrees can make a significant and easily perceivable difference. Optimal ramp angle isn’t just critical for World Cup racers, it is critical for all skiers. The easiest way to convince yourself of the importance of optimal ramp angle is for you to experience the effects of ramp angle through experimentation. How? With a Stance Ramp set to a base reference angle of 2.5 degrees.

The Stance Ramp lets skiers stand in their ski stance (barefoot is best) on a flat, level, surface then assume the same stance on the Stance Ramp, compare the kinaesthetic sense and judge whether they feel stronger of weaker. The angle of the Stance Ramp can be predictably increased or decreased by inserting shims at either end between the ramp and the surface it is supported on. When the ramp angle that makes the stance feel the strongest is arrived at, it can compared to the ramp angle of the ski boot board by having one foot on the Stance Ramp and the other in the ski boot.

The best part? The Stance Ramp is easy and inexpensive to make with readily available materials. I made mine out of some scraps of plywood I had lying around. Here’s what the Stance Ramp I made looks like. You stand with one foot on either side of the stiffener in the center with your heels at the high end (left end in the photo below).

IMG_6304

Here’s a top (plan) view. It is a good idea to check the surface the ramp will sit on to make sure it is very close to level.

IMG_6302

Here’s the underside of the Stance Ramp showing the element at the rear that gives the ramp its 2.5 degree angle. The stiffener in the center is important to ensure the ramp doesn’t flex under your weight.

IMG_6309

The sketch below is a basic plan for a Stance Ramp. The only critical details are the height or thickness of the element that lifts the rear aspect of the ramp to achieve and 2.5 degree angle (angle A) and the distance the lift element is placed from the front edge of the ramp. The stiffening element in the center of my ramp is 8 cm wide. The ramp has to be big enough to stand with the feet under the hips and long enough to accommodate the length of the feet.

Stance Ramp

An online right angle calculator such as the one at cleavebooks.co.uk can be used to calculate the spacing of the lift element from the low end (front edge) of the ramp based on its thickness.

SR calculate

Once the optimal ramp angle is arrived at, the Stance Ramp can be used in combination with the ski boot shell to confirm that the boot board is at the same angle.

IMG_6307

In my next post, I will discuss what I call the Resistive Shank Angle that is the base to build  a strong stance on.

FIFTH GENERATION STANCE RAMP ASSESSMENT DEVICE

Since my first version of the stance ramp assessment device I have made a number of significant improvements. The series of photos below are of the fifth generation device.

The bottom plate or base of the device is approximately 18 inches (46 cm) wide by 16 inches (41 cm) deep (front to back). I intend to make the next version about 22 inches (56 cm) wide by 18 inches (46 cm) deep. Size is not critical so long as the top plate is deep and wide enough for the feet being tested.

Stiffness of the plates is critical. Three quarter inch thick (2 cm) plywood or medium density fiberboard (MDF) are suitable materials. I added 1.5 inch x 1.5 inch wood reinforcing ribs on the sides, middle and rear of the top plate.

The photo below shows the heel end of the device. Two 1/4 inch drive ratchets turn bolts threaded into T-nuts in the top plate that raise the heel end up.

The photo below shows the top plate hinged to the bottom plate with 4 robust hinges.

Four telescoping hard nylon feet are set into the bottom plate to enable the device to be leveled and made stable on the supporting surface. It is important that the device not tilt or rock during testing.

The photo below shows the details of the interface between the top plate on the left and the bottom plate on the right.IMG_3409

I used gasket material purchased from an auto supply to shim the forefoot of my boot boards to decrease the ramp angle so as to obtain the 1.2 degree ramp angle I tested best at.Shim pack

The package contains 4 sheets of gasket material that includes 3 mm and 1.5 mm sheet cork and 2 other materials.Gasket

I cut forefoot shims from the 3 mm cork sheet as shown to the right of the boot board in the photo below.BB w shims

I adhered the shims to the boot board with heavy duty 2-sided tape and feathered the edges with a belt sander.shims installed

I corrected the ramp of my boot boards in 3 stages. Once my optimal ramp angle is confirmed, I will pour a boot board into the base of my ski boot shells in place of the existing boot boards using a material such as Smooth-Cast 385 Mineral Filled Casting Resin. More on this in a future post.

Ramp Angle Appears to User Specific

It is important to stress that although there appears to be a trend to optimal boot board ramp angles for elite skiers in the range 1.5 degrees or less, there is no basis to assume a  ramp angle that is optimal for one skier will be optimal for another skier. Recreational skiers are testing best between 2.0 and 2.5 degrees.

It is also not known at this point whether the initial optimal ramp angle identified with the device will change over time. Based on the impressive results seen so far in the limited number of skiers and racers who were tested and ramp angles adjusted there is no basis to assume that ramp angle is not a critical factor affecting skier balance and ski and edge control. Studies on this issue are urgently needed and long overdue.

It is important that testing for optimal ramp angle be preceded by kinesthetic stance training. This will be the subject of my next post.

A DEVICE TO DETERMINE OPTIMAL PERSONAL RAMP ANGLE

This post contains the most important information I have ever written on skiing. It concerns the important discovery I have made since I began to cast a critical eye on the positions of the various experts about 45 years ago; a method to determine the optimal personal ramp angle of a skier/racer.

By 1978, subjective experiments had taught me that a total ramp angle between the sole of the foot and the base of a ski of more than 3 degrees could have significant adverse effects on skier stability, balance and the ability to control the direction and especially the edge angle, of a ski. Wherever possible, I tried to limit total ramp angle (boot boards + bindings) to below or close to 3 degrees. But ski boot and binding construction often limited my ability to reach this objective. It was limitations in the construction of my current Head World Cup boot that presented challenges in getting the boot board ramp angle below 3 degrees. Through a concerted effort I had managed to reduce ramp angle to 3.3 degrees (bindings are zero) with a noticeable improvement in balance, ski and edge control. But the results of my recent NABOSO insole test suggested that the boot board ramp angle needed to be a lot lower.

The Dynamic Ski Stance Theory

A standard test of the human balance system is to subject a subject to dynamic changes in the platform under their feet. Over the past few years, I made numerous attempts to find the optimal ramp angle for skiing. One method involved assuming my strongest stance on a hard, flat level surface then stepping onto a plate shimmed to a fixed angle then repeating the process with the plate shimmed to a different angle. The results were inconclusive. Every time I went back to the hard, flat level starting surface my balance system seemed to reset. I had to get the angle of the tilted plate well over 3 degrees before I began to sense obvious instability. This led to my positing of a theory that the angle of a plate that a skier is standing on needs to be changed as the skier goes through a stance protocol designed to test stability and what I call a rooted or grounded connection where the skier feels as if their feet are literally rooted in the snow.

Research is Urgently Needed

Before I go any further I want to stress that I believe that an idea, no matter how compelling, is nothing more than a theory until it has been thoroughly tested and has withstood rigorous scrutiny. Even then, no theory should be immune to challenges. Research on this subject is urgently needed and long overdue. With this in mind, I designed the dynamic stance assessment device so it can be easily made with reasonable skills and readily available, inexpensive materials. I have recently completed a 4th generation prototype to serve this end. But a much more sophisticated device can and should be made and used by academic researchers. A servo motor driven ramp with a data acquisition package is the preferred option.

Stance Training is Essential

In order to obtain accurate results with the dynamic stance assessment ramp it is essential that the subject being tested undergo kinesthetic stance training and follow a protocol during testing that is designed to help the subject assess the effect of changes in ramp angle. It is disturbing that few of the skiers tested so far have a kinesthetic sense of the elements of a strong stance. Most have never sensed a strong stance. Worse, no ski pro or coach has ever discussed this crucial aspect of skiing with them. It appears as if it is simply assumed that a skier will automatically find their optimal stance. I can unequivocally state that this is not the case.

Dynamic Stance Ramp Test Results

  • The majority of skiers tested so far were most stable at ramp angles between 2.0 and 2.5 degrees.
  • A number of skiers, myself included, were most stable at close to or under 1.2 degrees.
  • One skier was most stable at 1.6 degrees.
  • One skier appeared to be relatively insensitive to ramp angle until it was above 2.8 degrees.
  • After training, most skiers were sensitive to changes of 0.1 degrees.
  • No skier tested so far was stable over 2.8 degrees.
  • Adding NABOSO insoles further reduced the ramp angle.

I tested most stable at 1.2 degrees; 2.1 degrees less than my existing boot board ramp angle. In order to reduce the boot board ramp angle to 1.2 degrees, I had to raise the toe end of my boot board 9 mm and lower the heel 2 mm for a total reduction of 11 mm.

First On Snow Impressions

Walking in my ski boots with the corrected boot board ramp angle immediately felt different. But the huge impact didn’t come until I started moving over the surface of the snow on my skis. Then the whole world seemed to change. I had a huge deja-vu moment; one that took me back to the solid, stable feeling I had under my feet in my first low-cut leather plastic soled ski boots. It was then that I realized that it was the jacked up heels of my first all plastic, rigid shell ski boots 45 years ago that had destroyed my balance and confidence on skis. This is a big miss for the ski industry, one that should have been caught by those who promote themselves as the experts in skiing, but wasn’t. This miss has huge implications for skiers at every level and ability all the way up to the World Cup. A skier, but especially a racer with a sub-optimal ramp angle will revert to an unstable weight on the heels, back seat Defensive Stance in which the skier is incapable of recruiting the enormous power of the glutes and optimal sensorimotor processes.

First generation device in action. Ratchet socket wrenches raise the ramp by turning bolts set into T-Nuts on each end.


Digital SmartTool electronic level accurate to 2 decimal places


Fourth Generation Stance Ramp assessment prototype. Two x two wood stiffening elements added to the platform.

The skiing of those whose ramp angle has been optimized is elevated to a whole new level provoking immediate comments like the difference is ‘night and day‘. After my transformation, I now believe that until ramp angle is optimized, everything else is irrelevant and that no amount of footbeds, orthotics, cants, alignment or custom fitting can overcome the adverse affect of sub-optimal ramp.

THE ZEPPA TIPPING POINT PROBLEM

A recent post on The Foot Collective FaceBook page titled Humans aren’t meant to walk on ramps!, highlighted the problems caused by elevating the heel above the forefoot known in the footwear industry as drop. Like the author of the post, I also wear zero drop shoes like Xero and Lems exclusively  (with NABOSO insoles) and spend all of my time indoors barefoot. Like the author, I too have experienced an immediate, unnatural and a sense of disorientation in terms of a connection with the ground, when I have worn dress shoes and winter boots with moderate drop.

While some amount of boot board ramp angle or zeppa appears to necessary for a strong, tensioned stance (what I refer to as a planted or rooted stance), the amount of zeppa is turning to be much less than I originally thought. It may be less than 1.5 degrees total (zeppa + delta). Assuming zero delta, there appears to be a very narrow range within which zeppa is optimal after which a tipping point is reached in terms of adverse effects on the motor control and balance systems.

It has also become apparent that some racers are tuning ski response by adjusting binding delta. Zeppa and delta each have a different effect on ski response especially edge control and the ability of a skier to resist the forces acting on them in the load phase of a turn. I will discuss issue this in a future post.


Humans aren’t meant to walk on ramps!

Powerful post by TFC Educator @optimize.physiotherapy
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Why do most shoes have a heel on them?
This really hit home the other day when I put on my winter boots (because it snows in November in Canada). Being someone who goes barefoot all day at work and at home (and wears zero drop shoes), it was a very unnatural feeling. It really threw my walking off, and I noticed the effects immediately. It changed the way I walked, stood, and made me use different muscles.
Humans are meant to have a flat base. No other animal wears mini ramps on their feet, but we do. The problem is that your body adapts to having a heel on, and it works different from a biomechanical perspective in any given movement pattern (the higher the heel, the worse the effect…but even most casual, running, and gym shoes have heels)


One thing it really does is affect your ankle/foot function. It has a huge effect on ankle ROM and tissue tension around the ankle. The problem is, when you wear a heel all day at work/at the gym/walking around, your tissues adaptively shorten and you don’t require as much ankle ROM. But then you take your shoes off and walk, go up your stairs, squat down to get things around the house etc. This is where people have issues. Not only at the foot/ankle but all the way upstream at other joints



Ankle ROM is incredibly important, and walking on a ramped surface all the time is incredibly unnatural. So do yourself a favour and spend less time in heeled footwear or get rid of it altogether


The Foot Collective is a group of Canadian physical therapists on a mission to help humans reclaim strong, functional and painfree feet through foot health education.

The Foot Collective are empowering people with the knowledge they need protect their feet from the dangers of modern footwear and the guidance to fix their own feet.

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