MEMO TO OLYMPIC ALPINE RACERS: PLEASE READ THEN FIX YOUR BOOTS

TONGUE TIED – https://wp.me/p3vZhu-uw

TONGUE SURGERY – https://wp.me/p3vZhu-w3

CLARIFICATION OF OBSTRUCTION TO FLEXION – https://wp.me/p3vZhu-fF

MOVEMENT OF THE SHANK IN THE SHAFT – https://wp.me/p3vZhu-u3

GETTING SHAFTED BY THE (SKI BOOT) SHAFT – https://wp.me/p3vZhu-tr

SKI BOOT ASSESSMENT PROTOCOL

Step 1 of the synergy 5 Step performance Program described in my last post is a Footbed Check using the Novel Pedar insole pressure analysis system.

Step 3 of the program is the Ski Boot Assessment detailed below. As with the 5 Step performance Program, the Ski Boot Assessment protocol and report were intended to serve as a template to base future programs on. The assessment report was intended to provide clients with information on the effects of their ski boots on their performance and/or as a work order for them to take to a boot-fitter to have any necessary issues identified in the report addressed.  Synergy Sports Performance Consultants Ltd. did not sell products or perform boot modifications.

 



My next post will be called FOOTBEDS: THE GOOD, BAD AND THE UGLY.

 

 

 

 

A FIVE STEP SKIER PERFORMANCE PROGRAM

Almost 40 years ago to the day, the head of the Whistler Pro Patrol, whose boots I had worked on, introduced me to Nancy Greene in the Roundhouse restaurant on top of Whistler Mountain. The rest is, as they say, history. Nancy asked me if I would work on her ski boots. She was so impressed by the results of my work that she approached the National Ski Team to make arrangements for me to work with some of Canada’s best racers.

Recently, while going through some archived files, I found copies of Nancy’s communication with the Program Director of the National Ski Team, Andrzej Kozbial. When Nancy approached me about working with our National Team, I stressed to her that I did not see any potential arrangement with the team as a job opportunity but instead as a vehicle where I could gain further experience and knowledge while providing a crucial service to the team and furthering the sport of skiing.

The graphic below is an excerpt copied from Nancy’s first letter of April 26, 1978 to the National Ski Team Program Director.

At the time that I wrote my US Patent 5,265,350 in early 1992, the intent and purpose of the detailed and lengthy specification was to provide a repository of the knowledge I had acquired to date to serve as a legacy for skiers and skiing to help advance the sport. While this information was in support of the inventions disclosed in the patent, the majority of the information was not subject to protection under the terms of the patent. The information was open access to the world. This was my intent.

In spring of 2000, I formed a company with 2 partners for the 2000-2001 ski season called Synergy Sports Performance Consultants Ltd. The objective of the venture was to gain further experience and knowledge and create a model that could be used as a template for future skier performance programs.

The following series of graphics are from Power Point presentations synergy made to ski schools.

The following graphic is the poster that described the synergy 5 Step Performance Program.

5 Step Performance Program description

The synergy Analysis Program looks at how your body interfaces with your ski equipment; primarily your footbeds and boots because this is the connection to your equipment and through it to the snow.

Synergy offers the program as a package made up of 5 components. They can either be taken as the complete package [recommended], several components or steps at once, or one component at time. Synergy recommends that you begin at step 1 and follow the sequence in numerical order. But the order can be arranged however you wish to suit your needs. The choice is yours.

1.Biomechanical Assessment

Good foot function is the key to control. That’s why the first thing we thing we assess is your biomechanical function. What that means is that we look at how well your foot and lower limb works. The examination is done by a podiatrist who looks at how your foot functions and how the lower limbs all connect.  Then we see how effectively your feet interface with the ground by putting you on insoles that read the pressures under your feet. We coach you through some balance movements while we watch how your foot functions while our computer records the results

2. Footbed Assessment

Footbeds can have a positive, neutral or negative effect on the function of your feet.

That’s why the next thing we check is how your foot interfaces with your footbed or orthotic.  We make sure that it allows your foot to function as well as it should without one.  And if your foot needs some assistance for optimal function we make sure the footbed is helping your foot do what it needs to do.

3. Ski Boot Assessment

Now that your foot is functioning optimally we make sure your ski boot lets it keep functioning. We conduct a thorough examination of your boot and provide you with a report that tells you how your boot is affecting your performance. Most important, we tell you what has to be done to fix the problem.

4. Kinesthetic Training

Skiing is about making the right moves. Kinesthetic Training is next. It teaches you how to tell when your body is making those moves. What is Kinesthetic Training? In simple terms it means to train your body to associate a feeling or sense with the right movements made at the right time. It is feeling and bringing about an awareness so you know when you are doing it right because we have taken you there and you have felt it. A picture may be worth a thousand words, but in skiing a feeling is worth a thousand pictures. We bring you to understand what you should feel in your foot at the start of the turn and then what it feels like to settle and balance onto the foot that drives the ski. By acquiring this sense you become more aware of how to allow your foot to transfer energy directly to the edge of the ski by using the body the way it was designed to be used. Remember, your body was not made to be a lever.

5. On-Hill Data Collection

This is where everything comes together. We move to the ski hill for this part of the package. We meet up top on Whistler or Blackcomb Mountain. We put our pressure insoles in your ski boots.  A pair of cables from the insoles goes up your ski pants where it connects to the data box [a kind of mini computer] we attached to your waistband.  Then we go out for a run on moderate, groomed terrain.  We record data in three takes in medium radius turns at a speed you are most comfortable with. While this is happening we videotape your skiing. Then we head into the lodge and synchronize the video with your foot pressure data. When this is done we watch your foot function in your boots on the computer screen on one side while we study your ski video on the other side of the screen. This way we confirm that your foot is functioning optimally as confirmed by analyzing your movement patterns and the timing of your skills.

My next post will be on the synergy Boot Assessment program.

 

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
👣
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.

http://www.thefootcollective.com

BEYOND BIOMECHANICS BY DR. EMILY SPLICHAL

The following post appeared on the Evidence Based Fitness Academy (EBFA) fitness blog on February 6, 2018 under the title Beyond Biomechanics | Addressing Foot Pain with Sensory Stimulation (1.).

I have reproduced the post with the kind permission of Dr. Emily Splichal under the title Beyond Biomechanics by Dr. Emily Splichal because her emphasis on the role of sensory stimulation of the plantar foot on foot, lower limb and function of the entire body has both direct application to and implications for, skiing.

I have a theory on what I call The NABOSO Effect that explains how I think NABOSO insoles improve dynamic stability in the biokinetic chain that I will discuss in a future post. I have been testing NABOSO 1.0 and 1.5 for months.


Beyond Biomechanics | Addressing Foot Pain with Sensory Stimulation – by Dr. Emily Splichal

I want you to picture a human foot.   Now picture a person standing barefoot, and then walking barefoot.   Do you see the foot striking the ground and flexing under impact, only to re-stabilize and push off just a few milliseconds later?

Often times when we think of human movement we can’t help but to be drawn to the thought of joints moving and muscles contracting.   Or in the case of foot function we are quick to consider the mechanics of flat feet, high arches, pronation and supination.   However when we delve deeper into the science of human movement there is more than meets the eye.

The Two Sides of Foot Function

When I teach on behalf of EBFA Global or speak to my patients I always emphasize that there are two sides to foot function (and dysfunction) – biomechanical and neuromuscular.    Now both play an important role in foot function which means that both must be appreciated – however to solely treat foot pain with just one belief system in mind is inherently flawed.

In most Podiatric Medical Schools we are taught foot function and foot pathology solely from a biomechanical perspective.

This means that every patient is tested for foot mobility and told to stand statically to determine arch height and foot type.   Based on this foot-focused biomechanical assessment and foot classification system the patient’s cause of injury and treatment protocol is determined.   Some of the favorite treatment recommendations include motion-controlled footwear and custom-posted orthotic both of which are prescribed with the hopes of controlling foot-focused biomechanics and thereby reducing their foot pain.

Beyond Biomechanics

The other side of foot function is one that is driven from a neuromuscular perspective and integrates the science of sensory stimulation and fascial systems.   In the case of neuromuscular function every patient would be assessed for sensitivity of plantar mechanoceptors as well as co-activation patterns between the foot and the core.  The role of minimal footwear, myofascial releasing, breathing patterns and compensation patterns more proximal would all be considered.

So which is more appropriate?  Well it depends.   In certain cases there will be a stronger argument towards a more biomechanical influence and in others it is more sensory.  This means it really is a marriage between the two approaches that provides the greatest patient outcome.

Sensory Stimulation in Foot Pain

My practice and Podiatry career is built around bringing an awareness to the important role sensory stimulation has on foot function and foot pain.

With every step we take impact forces are entering the foot as vibration.  This vibrational noise stimulates unique mechanoceptors on the bottom of the foot and is used to coordinate the loading of impact forces through coordinated contractions of the intrinsic (small) muscles of the bottom of the foot.   This co-contraction leads to a stiffening or strengthening response of the foot.

Researchers such as Nigg et al. and Robbins et al. have demonstrated a direct relationship between sensory stimulation of the plantar foot and intrinsic muscle strength concluding that one is necessary for the other.   This means that if our footwear or orthotics disconnect us from sensory stimulation – as in the case of cushioned footwear – this can actually weaken our foot making us susceptible to plantar fasciitis, Achilles tendinitis and stress fractures.

Beyond Vibration Stimulation

Vibration stimulation is an extremely important sensory stimulation that enters our foot however it isn’t the only stimulation.   Another important stimulation is the ability for our foot to determine texture and if a surface is rough or smooth.   This information is used to help maintain dynamic balance (think walking on ice).

Enter the merkel disk mechanoceptors.   These superficial sensory nerves are used to determine what’s called 2 point discrimination which is translated to roughness or the texture of a surface.  Surface texture and insole texture is one of the most studied aspects of foot stimulation and posture or gait.  From decreased medial lateral sway in patients with Parkinson’s or MS to reduced prefrontal cortical activity in atheltes post-concusion the applications are promising!

One area that hasn’t been focused on for sensory stimulation and foot function is foot pain.  I am here to change the awareness around this concept and share the powerful application of sensory stimulation and foot pain.

As we mentioned earlier sensory stimulation of the foot leads to a contraction of the intrinsic muscles of the foot.   Intrinsic muscle contraction is not only a criticial step in the damping of impact forces but has also been shown to increase the medial arch and build co-activation contractions in the core.

 The Evolution of Textured Insoles

In October 2017 Naboso Technology launched the first-ever commercially available textured insole!   Naboso Technology essentially brought the science of touch and years of textured insole research to the market place giving new hope to people with foot pain.

Available in two strengths – Naboso 1.0 (1mm texture) and Naboso 1.5 (1.5mm texture) Naboso Insoles are designed to be worn without socks (or at the most very thin socks).  They fit into all footwear, are freely movable in all planes of motion and are only 3mm thick.

FROM THE GROUND UP

Are you barefoot strong?


Learn more about the power of texture! – http://www.naboostechnology.com

  1. https://barefootstrongblog.com/2018/02/06/beyond-biomechanics-addressing-foot-pain-with-sensory-stimulation/

 

THE SHOCKING TRUTH ABOUT SKI BOOTS

In this post, I will expand on the content of The Shocking Truth About Power Straps (1.) which was by far the most popular post since I started this blog in 2013.

While the truth about what power straps can potentially do if improperly adjusted is shocking, the lack of support in principles of applied science for the basic premise that I describe as indiscriminate envelopment as the approach to achieving a fit of a ski boot with the foot and leg of the user with the objective of substantially immobilizing it’s joints with unknown consequences, is even more shocking. Little or no consideration appears to be given to the effects of indiscriminate envelopment on the balance and motor control systems of the skier.

What is done to the foot and (lower) leg can affect the entire body. In his post, Foot biomechanics is dead. Discuss (2.), Professor Chris Nester states:

The foot is not a compilation of interconnected mechanical components that respond precisely to the laws of mechanics. It is a complex matrix of at least 11 biological tissues (i.e. skin, fat, muscle, tendon, joint capsule, ligament, bone, cartilage, fascia, nerves, blood vessels….) that responds to external loads through the symbiotic relationship between the motor control system and tissue properties.

Professor Nester goes on to state:

I believe the integration of our current foot biomechanics knowledge with insights from motor control, neurophysiology and related domains (e.g. tissue biology) will drive advances in foot function more than pursuing a pure mechanics paradigm.

Professor Nester proposes that the term biomechanics be replaced with the term Neurobiomechanics. I concur.

How Does the Ski Boot Affect the Human Performance of the Skier?

The short answer is that when the structures of a ski boot indiscriminately envelop the structures of a foot and a portion of the leg (aka the Perfect Fit or the Holy Grail), no one knows. While it is essential that a ski boot create a secure connection of the foot of a skier with the ski, it should not achieve this connection at the expense of natural neuromuscular function, especially balance.

In 1980, when I was about to prepare a new pair of Lange race boots for Steve Podborski, I asked myself whether it was possible to obtain a secure connection of the foot with the ski without compromising natural neuromuscular function or, even better, was it possible to enhance natural neuromuscular function?

I took a significant step towards answering this question in 1980 when I designed and fabricated a device I called a Dorthotic. The Dorthotic supports the upper or dorsal aspect of the foot as opposed to supporting the plantar aspect (i.e. the arch). My theory that loading the top of the foot or dorsum with a force perpendicular to the transverse or medial-lateral plantar plane of the foot has positive benefits for motor control and balance has begun to be recognized. The Dorthotic enabled Steve Podborski to compete and win on the World Cup Downhill circuit mere months after reconstructive ACL surgery and to eventually win the World Cup Downhill title, a feat no non-European has repeated. US and international patents for the dorsal device were awarded to me (David MacPhail) in 1983.

The success of the Dorthotic gave me a start towards answering the question of whether a secure connection of the foot with a ski was possible without compromising natural neuromuscular function. But I knew that I needed to learn a lot more. I realized that finding the answers I was seeking and especially unraveling the secret that enables the world’s best skiers to stand and balance on their outside ski, would require a multi-disciplinary approach.

The Missing Factor in Skiing: A Multi-Disciplinary Approach

A significant influence that served as the impetus for the design of the Birdcage research vehicle and the on-snow studies, was the work of Dr. Benno Nigg. In 1981, Dr. Nigg accepted an invitation to move from ETH Zurich, where he was the director of the biomechanics laboratory, to the University of Calgary, where he founded and developed the Human Performance Laboratory (HPL), a multi-disciplinary Research Center that concentrated on the study of the human body and its locomotion.

The publication of the Shoe In Sport in English in 1988 served as a seque to introduce me to Nigg’s research at HPL. Studies done at HPL found that any interference with the function of the human foot, even a thin sock, extracts a price in terms of the adaptive process the human body has to undergo to deal with what is really an externally imposed disability.

The Effect of Footwear on the Neuromusculoskeletal System

There is an excellent discussion in a recent post on the Correct Toes blog (3.) on the impact of a narrow toe box, toe spring and elevated heel of traditional footwear on the human body. Elevating the heel in relation to the forefoot will predictably cause a realigment of the ankle-knee-pelvis joint system with a corresponding adjustment in the tension of the associated muscles with a global effect on the Neuromuscularskeletal System. This has been known for decades. Elevating the heel in relation to the forefoot, will cause the ankle joint to plantarflex (reduce dorsiflexion) in relation to the support surface under the foot in order to maintain COM within the limits of the base of support.

Ramp Angle Rules

Due to the unstructured nature of the indiscriminate envelopment characteristic of the fit of the majority of conventional ski boots, it is extremely difficult, if not impossible, to determine the effect of constraint of this nature on the Neuromusculoskeletal System. So I’ll focus on the one aspect of the ski boot that has consistent and profound implications on skier human performance, especially motor control and balance; boot board ramp angle or zeppa. Binding ramp angle or delta compounds any effect of zeppa. For the sake of simplicity we’ll assume zero delta.

Contrary to the widely help perception, raising the heel of a skier in a ski boot does not cause CoM to move forward. In fact, it usually has the exact opposite effect. It puts a skier in the back seat with the weight on their heels. Worse, it can disrupt the competence of the biokinetic chain that dynamically stabilizes and protects the joints of the lower limbs. Excessive heel elevation can render a skier static and cause the balance system to resort to using the back of the shaft as a security blanket.

As of this writing, I am unaware of any standard within the ski industry for zeppa. It appears to be all over the map with some boots having as much as 6.5 or more degrees. The default zeppa for the human foot on a hard, flat level surface, is zero.

Through subjective experiments in 1978, I arbitrarily determined that zeppas in excess 3° had a detrimental affect on skier balance. In 1991, zeppas of 2.3° and 2.5° were chosen for the large (US 8-12) and small (US 4-8) Birdcages based on an analysis of the effect of ramp angle on COM and neuromuscular activity. This range appears to work for a majority of recreational skiers. But recent tests with a dynamic ramp angle assessment device that I designed and fabricated is finding the stance of elite skiers optimizes at much lower zeppa angles, with some skiers below 1.5°. Interestingly, when NABOSO insoles are introduced for the assessment, zeppas decrease even further. With minimal training, most skiers are sensitive to dynamic changes in zeppa of 0.1 degrees.

Implications for the future of skiing

A tectonic shift is underway on a number of fronts (see A Revolution) that is challenging the mechanical and static premises that form the underpinnings of the key positions in ski teaching and the design of equipment such as ski boots and the fit process. In my next post I will post recent material by Dr. Emily Splichal, functional podiatrist and inventor the revolutionary NABOSO small proprioceptive stimulating insole.


  1. https://wp.me/p3vZhu-UB
  2. https://talkingfeet.online/2018/01/18/question-3-foot-biomechanics-is-dead-discuss/
  3. https://www.correcttoes.com/foot-help/footwears-impact-musculoskeletal-system/

THE MECHANICS OF BALANCE ON THE OUTSIDE SKI: BALANCE PLATFORM MECHANICS

Turntable rotation generated by the powerful internal rotators of the pelvis (the gluteus medius and minimus) in combination with second rocker mechanics can create a platform under the body of the outside ski and foot that a skier can stand and balance on using the same processes to balance on solid ground. The associated mechanics creates a platform under the body of the outside ski by extending  ground reaction force acting along the portion of the inside edge in contact with the snow, out under the body of the ski.

In order to understand the mechanics, we need to start with a profile through the section of the body of the ski, binding and boot sole under the ball of the foot. The graphic below is a schematic representation of a ski with a 70 mm waist and 100 mm shovel and tail with an arbitrary length of 165 mm. The total stack or stand height from the base of the ski to the surface of the boot that supports the foot is 80 mm. The uppermost portion of the schematic shows the shell sidewalls of a 335 boot in relation to the 70 mm width of the stack. A ski with a 70 mm waist will place the center ball of the foot of skiers with US Men’s 10 to 12 feet close to over the inside edge. The heavy black line at the bottom of the stack shows the projection of the sidecut width beyond the waist.The schematic serves as a base on which to overlay a free body diagram showing the forces acting across the interface of the inside edge with the snow. This is where the rubber meets the road.

There are two possible scenarios in terms of the axis on which the center of pressure W of the skier will act. Unless the foot can sufficiently pronate and especially generate impulse second rocker loading, W will lie on the proximate anatomic center of the foot and transverse center of the body of the ski as shown in the graphic below. In this location, W will create a moment arm due to the offset with the GRF Pivot under the inside edge at the waist. The resulting moment of force will externally rotate the ski and foot under load out of the turn while simultaneously rotating the leg externally.The graphic below shows the second scenario where the center of pressure W lies directly over the GRF Pivot under the inside edge. In this position, W will load the inside edge under the ball of the foot and assist edge grip. But in this configuration, rotating the ski onto its inside edge necessitates overcoming the moment of force created by the moment arm resulting from the offset between the GRF Pivot and GRF acting at the limits of the sidecut. This requires a source of torque that acts to rotate the ski into the turn about the pivot acting at the inside edge at the waist of the ski.An obvious source of torque is to use the leg to apply force to the inner aspect of the shaft of the foot; aka knee angulation. But this will not create a platform under the body of the outside ski. Applying a load to the vertical wall of the shell opposite the ball of the foot will apply torque load to center at the GRF pivot as shown in the graphic below. The moment arm is formed by the point at which the Turntable Torque is applied to the boot sidewall (green arrow) to the center of rotation at the GRF Pivot.

 

The torque applied to the vertical sidewall of the boot shell is the Effort. The sidecut of the ski is the resistance. What effect will this have on the body of the ski under the foot? There is a lot more to this subject that I will begin to expand on in my next post.