Ramp Angle posts

NABOSO: FEEL THE FORCE

To Dr. Emily Splichal

In recognition of Dr. Emily Splichal’s contribution to my knowledge and through the knowledge gleaned from the use or her pioneering NABOSO surface science technology I am dedicating this post to her as my teacher, mentor and inspiration. Thank you Dr. Splichal.


In this post I am going to discuss how NABOSO surface science technology gave me the feedback mechanism to confirm the optimal ramp angle I needed to transition to a higher level of skier performance.

Optimal Ramp Angles starts with Stance Training

My transition started with refinements to my stance that came from incorporating Dr. Splichal’s principles of foot-to-core sequencing (that connects the feet with the pelvic core) and body fascial tensioning (that unifies the body). Prior to these changes my stance is what I would now define as good but not optimal. The huge improvement resulting from the refinements served as the impetus for a series of posts on the sequencing process required to assume a fascially tensioned stance with foot to core sequencing. I called this the SR Stance. The reason I chose this name was to draw reader attention to the stance posts by making the stance seem innovative, but not intimidating.

KIS is the Stance Kiss of Death

In reviewing material on ski technique, a skier’s stance is described as anything from an athletic stance, a relaxed stance, a ready stance, a balanced stance, a centered stance or a whatever feels good stance. A focus on selling skiing as easy with the KIS principle (Keep It Simple) has resulted in stance being perceived as less than critical to good technique. This leaves most skiers with the impression that a ski stance should feel similar to a relaxed upright stance on two feet with weight equally distributed between both feet and the heels and forefoot of each foot. This is interpreted by skiers as meaning they are balanced or in balance. So it follows that in actual skiing there should be even ‘pressure’ everywhere with no sensation of pressure on any specific area of the foot.

If I ask a typical skier to stand on a ramped surface and assume their ski stance they will find the sweet spot where their weight feels evenly distributed and identify it with their ski stance regardless of the  angle of the surface

So the first challenge to transitioning to a higher level of skier peformance is accepting that a strong ski stance must be learned and consistently rehearsed by doing drills as I do every time I go skiing. It’s like pre-flight check. NABOSO provide the conscious and subconscious CNS feedback that tells me when I am cleared for take off.

The NABOSO Effect

In my post NABOSO PROPRIOCEPTIVE STIMULATION INSOLES, I stated that the principle proprioceptive neural activity associated with balance responses occurs across the plantar plane. It is strongest in the 1st MPJ (big toe joint) and big toe. The fast acting small FA II nerves in this area are activated by pressure and skin stretch both of which occur in the late phase of Mid Stance. Optimal ramp angle is critical because it maximizes both pressure and skin stretch thereby potentiating the sensory input required to initiate controlled movement.

Assuming a NABOSO is trimmed, if necessary, to fit a shoe, there will be a positive effect on plantar proprioceptive stimulation. But my experience to date has been that the plantar proprioceptive stimulation will be much more pronounced in a minimal, zero drop shoe with adequate width for fascial forefoot tensioning and correct alignment of the big toe.

The big breakthrough for me came after I started using NABOSO insoles in shoes with different heel raises (drops). It turned out that I had the highest perception of  pressure under the ball of my foot in late mid stance phase with shoes with zero ramp (drop). When I put NABOSO insoles in my ski boots to test them I could hardly perceive any pressure under the ball of my outside foot during skiing no matter how I adjusted my stance or the tensions in my boot closures. This told me that my ramp angle of almost 3 degrees was far too great. As soon as I reduced the angle to 1.2 degrees (which is what I tested best at on my dynamic ramp angle device) it is no exaggeration to state the the whole world changed. But the transition effect didn’t kick into high gear until this ski season after my brain had time to delete a lot of the bad programming from the old ramp angle.

NABOSO 1.0 on the left. NABOSO 1.5 on the right. I use 1.5 in my ski boots. I purchase the large size and trim to fit.

Tentative Conclusions

  • A system that provides continuous subconscious sensory input to the CNS with the ability to consciously sense sensory input during drills in executive mode is important.
  • Stance training should be incorporated into racer training programs at an early stage and optimal stance ramp angle identified and implemented.
  • Once optimal ramp angle has been implemented the boot should be set up to the skier’s functional specification which I will discuss in future posts.
  • Stance ramp angle should be retested on a periodic basis to confirm the requirements have not changed.
  • Adjustments should be made as soon as possible after the end of a competitive season and no further changes made during the subsequent competitive season.

In my next post I will discuss Dr. Splichal’s protocol for using NABOSO insoles and matts in training.


Disclosure

I am not involved in any form of business association or affiliation or any have business interest or investment with Dr. Splichal/NABOSO/EBFA. Nor do I receive any form of compensation from the sale of NABOSO. Prior to marketing her NABOSO insoles Dr. Splichal provided me with a small sample of NABOSO material at her cost to cut insoles from for testing.

 

 

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?

 

WHY STANCE TRAINING IS ESSENTIAL

When readers click on my blog address at skimoves.me, analytics give me a hierarchy of the countries with the most views and the most popular posts in ascending order. This helps me identify which content resonates most strongly with viewers and which content draws a blank.

As I write this post, the top five countries are the US followed by Croatia, the United Kingdom, Slovakia and France.

The most viewed post today is THE SHOCKING TRUTH ABOUT POWER STRAPS; far and away the most popular post I have published to date. But the most important posts by far that I have ever written, A DEVICE TO DETERMINE OPTIMAL PERSONAL RAMP ANGLE and STANCE MUSCLE TENSIONING SEQUENCE EXERCISE barely sputtered in comparison. This strongly suggests that far from just some small gaps in the knowledge base skiing is founded on, massive craters exist.

Arguably the most important aspect of skiing is a strong stance. Any variance in the fore-aft angle of  the plane of support under the feet and the plane of the base of the ski has significant impact on stance. Yet these subjects are barely blips on the Doppler Radar of the ski industry.

Since I started the dynamic ramp angle assessment project a few weeks ago I have found that when asked to do so, it is rare for a skier of any ability to be able to assume a strong ski stance in an off the ski hill environment. Even when a skier  skis with a relatively strong stance, they seem to lack a sense of what a strong stance feels like. Because of this, they lack the ability to consciously replicate a strong stance. If asked to do so, they would be unable to coach a skier in the sequence of events that I described in my last post

In the dynamic ramp angle assessment project, I  have also observed that skiers with with a boot/binding ramp angle greater than 2.8 degrees appear to have become accustomed to the associated unstable, dysfunctional feeling and identify with it as ‘normal’. Before I can test them, I have to spend time coaching them into the correct stance because it feels unnatural to them.

When I go back and forth between a strong functional stance on a flat, hard level surface to a stance on the dynamic ramp angle device set to an angle of 4 degrees, I can get close to the same angles of ankle, knee and hip. But when I do, I feel strong tension, stiffness and even pain in my mid to lower back which is  common in some skiers and even racers.

Based on results to date with the dynamic ramp angle device, it appears as if strong skiers ski best with ramp angles close to zero. But depending on their sense of balance and athletic ability, they may have a wide range in which they sense little difference on the effect of ramp angle until they approach the upper limit of stability. While they may be able to ski well with a ramp angle close to the maximum limit of stability, ramp angles much above 1.2 to 1.5 degrees may not offer any benefits. This can only be tested on skis where balance is tested by dynamic forces which cannot be replicated in a static setting.

Issues affecting skier stance were discussed in detail in my post, THE SHOCKING TRUTH ABOUT POWER STRAPS. Here are the excerpts I posted from the chapter on The Ski Boot in the book, The Shoe in Sport (1989), published in German in 1987 as Der Schuh Im Sport– ISNB 0-8151-7814-X

“If flexion resistance stays the same over the entire range of flexion of the ski boot, the resulting flexion on the tibia will be decreased. With respect to the safety of the knee, however, this is a very poor solution. The increasing stiffness of the flexion joint of the boot decreases the ability of the ankle to compensate for the load and places the entire load on the knee”. – Biomechanical Considerations of the Ski Boot (Alpine) – Dr. E. Stussi,  Member of GOTS – Chief of Biomechanical Laboratory ETH, Zurich, Switzerland

“The shaft of the boot should provide the leg with good support, but not with great resistance for about two thirds of the possible arc, i.e., (14 degrees) 20 to 22 degrees. Up to that point, the normal, physiologic function of the ankle should not be impeded”.

“Previous misconceptions concerning its role in absorbing energy must be replaced by the realization that shaft pressure generates impulses affecting the motion patterns of the upper body, which in turn profoundly affect acceleration and balance.

“When the lateral stability of the shaft (the leg) is properly maintained, the forces acting in the sagittal direction should not be merely passive but should be the result of active muscle participation and tonic muscular tension. If muscular function is inhibited in the ankle area, greater loads will be placed on the knee”. – Kinematics of the Foot in the Ski Boot – Professor  Dr. M. Pfeiffer – Institute for the Athletic Science, University of Salzburg, Salzburg, Austria

It has been over 40 years since international authorities on sports science and safety raised red flags concerning the adverse effects of ski boots design and construction on skier stance, balance and the potential to cause or contribute to injury. It is time that their concerns were taken seriously and acted on. Research on stance and the effect of such things as zeppa and delta ramp angles is urgently needed.

 

ISOMETRIC STANCE MUSCLE TENSIONING SEQUENCE

Tensegrity

Tens(ion) + (Int)egrity 

The optimal ramp angle, as determined by the dynamic ramp device, is based on a stance predicated on the principles of Biotensegrity.

Fascial continuity suggests that the myofascia acts like an adjustable tensegrity around the skeleton – a continuous inward pulling tensional network like the elastics, with the bones acting like the struts in the tensegrity model, pushing out against the restricting ‘rubber bands: Tom Myers, Anatomy Trains (1.)

A ski stance based on the principles of bio-tensegrity must be learned and rehearsed in a step-by-step process. It is neither natural or intuitive although elite skiers and racers such as Shiffrin and Hirscher appear to have acquired the elements of Biotensegrity. Assuming a group of racers of equal athletic ability, the odds will favour those whose stance is based on Biotensegrity.

In a ski stance based on bio-tensegrity, tension in the arches of the feet extends to from the balls of the feet to the palms of the hands holding the poles.

  1. Start by standing barefoot on a hard flat floor or surface in a controlled environment such as your home. Where possible, use the same surface and place to rehearse the stance. If you have constructed a dynamic ramp assessment device, use this with the top plate set to level.
  2. Stand upright at attention. You should feel most of the weight under your  heels and less weight across the balls of your feet. This is normal. The fore-aft weight distribution is actually 50-50 heel to forefoot. But because the weight of the body is spread across the balls of the feet and along the outer aspect behind the small toes, more weight is sensed under the heels. Stand so your weight is distributed equally between both feet.
  3. Relax your hamstrings (in your thighs) and let your torso drop towards the floor.  Your knees will move forward as they flex and your ankles will dorsiflex. Your ankles should stop dorsiflexing on their own when the front of your knee caps are aligned approximately over the balls of your feet. This is the point where the tension in your soleus (calf muscle) peaks with the tension in plantar ligament of your arches. You should feel about the same pressure under the balls of your feet as you feel under your heels. But it should feel as if the circle of pressure under your heels has gotten bigger and your feet are more connected or integrated with the floor. I call this ‘rooted’ because it should feel as if your feet have sunk into the floor.
  4. While keeping your upper body erect, move slightly forward in the hips. You will quickly reach a point where you start to become unstable and feel as if you would fall forward onto your face if you moved farther forward in the hips. When you get to this point your big toes should press down on the floor on their own to try stabilize you. This is the forward limit of stability.
  5. Now move rearward in the hips until you start to feel the same instability. This is the rearmost limit of stability.
  6. Now bend forward from the waist. Do not curl your back. Bend from the hip sockets for the thigh bone (femur). This movement is actually thigh flexion. Lift your thigh to get the right feeling. As you bend forward from the waist, your buttocks will move rearward and upward as your ankles and knees straighten.  Reach forward with your arms as if you were going to hug a large barrel in front of you. Make sure the palms of your hands are facing each other with fingers curled and pointing towards each other.
  7. Find the place where your arms and head feel neutral to your spine. As your arms come into position you should feel your abdominal core and muscles in your back acquire tension. Slings Isometric stance
  8. Experiment by moving forward and rearward in the pelvis. As you move forward in the pelvis the pressure should increase under the balls of your feet. But you should not feel unstable. If anything, you should feel stronger and more stable. You should feel as if the weight of your head and shoulders is pressing your feet down into the floor.
  9. Increase the bend at your waist while keeping the pressure on the balls of your feet and heels until the top of your head is down by your knees. You should still feel very strong and stable in the feet. This is the lowermost limit of waist flexion.

Once you have acquired a kinesthetic sense of the bio-integrity of foot to hand tension, a sense of stability while pulsing the torso vertically up and down over the feet confirms a state of bio-tensegrity.

The photo below is of simple model I designed and constructed in 1993 to illustrate the basic concept of bottom up Biotensegrity and how the degree of passive tension in the plantar ligament of the arches of the feet and the vertical biokinetic chain is driven by the compression from weight of COM stacked over the foot.

The graphic below shows the continuum of tension from the balls of the feet to the opposite shoulders through the mechanism of the oblique posterior sling.

In my next post I will discuss what I term the NABOSO Effect.


  1. https://www.anatomytrains.com/fascia/tensegrity/

A DEVICE TO DETERMINE OPTIMAL PERSONAL RAMP ANGLE

This post contains the most important information I have ever written on skiing. It concerns the most 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.

MORE ON ZEPPA (BOOT BOARD) RAMP ANGLE

Slowly, but definitely, the ski community are learning the positive boot board (zeppa) ramp in many boots is excessive and not beneficial to many of us. Excessive seems to be anything over approximately 3.0 degrees. The lowest ramp I have measured to date was 2.4 degrees in the latest Dalbello DRS boot in a Mondo 27. A size 23 is still over three degrees.

I believe most manufacturers have too much ramp in their boots. As explained in a recent post, the problem is worse for smaller boots, since as boots shorten, ramp increases. Still, even if boot ramp is correct, we should wonder if binding designers think boot designers need some design help, since nearly all bindings have positive ramp (delta) of at least a few degrees for Mondo 27 boots.

Like boot zeppas, as binding toe and heel are mounted closer together, delta increases and is additive with boot ramp. Further, there are additional changes to boot angle since binding delta tilts the entire boot, It also alters effective forward lean.

I believe when we demo skis, a portion and perhaps a substantial portion, of the differences we feel between skis, may be accounted for by the differences between ski binding ramp angles. At the very least, binding angles can corrupt on-snow testing of skis and/or boots. If you are working to get your boot setup perfectly adjusted to your preferences, why allow binding ramp variables to alter an optimal configuration?

In my opinion, the best solution is a 0 degree binding delta. If this is not achievable, at least set all skis bindings to the same delta. This may be easily, achievable. Most manufacturers make shim kits for at least some of their bindings. Shims appear to be available for most bindings used on race skis that allow incremental changes to 0 degrees delta. However, not all shops know of the existence of these shims since  kits are usually in the race catalogue, not the recreational product catalogue.

If alterations to either binding heel or toe height are made, an equal change must be made to screw length or there will definitely be an unsafe situation. Binding holes are between 8.5 and 9.0mm deep. Be certain screw threads do not extend more than that amount from the bottom of the binding.

One last thing to remember is that moving binding position forward or backward on the ski could subtly alter binding delta since the top surface of skis are crowned. Moving the bindings to a new position on the crown will affect the height of the heel and toe. If bindings are moved after setting binding delta, it should be checked again.

I always prefer to direct measure rather than use a calliper and calculate zeppa or delta. The photos below show a device I had fabricated that allows the angle of a zeppa to be measured between the two primary load points under the heel and the head of the first metatarsa (aka ball of the foot). The distance between the rods can be adjusted to these two points on a zeppa or to the 2 points of contact of a boot sole on the heel and toe pieces of a binding.

img_0739

The SmartTool digital level shown in the photo below accurately reads to one decimal place.

img_0743

The SmartLevel is too long to sit properly on a zeppa. The two rods of the frame that supports the level lets me avoid toe kick or any other shapes that can distort ramp angle.  I just measure the angle directly between the two points of support.


Lou Rosenfeld has an MSc. in Mechanical Engineering with Specialization in Biomechanics earned at the University of Calgary Human Performance Laboratory. His research was titled, “Are Foot Orthotic Caused Gait Changes Permanent”.

While at HPL, he assisted with research on the effects of binding position for Atomic, and later conducted research for Nordica that compared Campbell Balancer established binding position to the Nordica factory recommended binding position.

Lou is one of the invited boot-fitters on the EpicSki forum “Ask the Boot Guys” and has authored articles on boot fit, balance, alignment and binding position for Ski Canada, Ski PressSuper G, Calgary Herald, and Ski Racing, USA. He is a CSIA Level 2 instructor and CSCF Level 1 coach. He currently resides in Calgary where he owns and operates Lou’s Performance Centre. A selection of his articles may be found at www.Lous.ca.