Footwear science posts

THE MECHANICS OF BALANCE ON THE OUTSIDE SKI: THE ROCKER/TURNTABLE EFFECT

The Two Phase Second Rocker (Heel to Ball of Foot) described in the previous post is dependent on inertia impulse loading. A good discussion of the basics of inertia and momentum is found in Inertia, Momentum, Impulse and Kinetic Energy (1.)

Limitations of Pressure Insoles used in Skiing

A paper published on May 4, 2017 called Pressure Influence of slope steepness, foot position and turn phase on plantar pressure distribution during giant slalom alpine ski racing by Falda-Buscaiot T, Hintzy F, Rougier P, Lacouture P, Coulmy N. while noting that:

Pressure insoles are a useful measurement system to assess kinetic parameters during posture, gait or dynamic activities in field situations, since they have a minimal influence on the subject’s skill.

acknowledge limitations in pressure insoles:

However, several limitations should be pointed out. The compressive force is underestimated from 21% to 54% compared to a force platform, and this underestimation varies depending on the phase of the turn, the skier’s skill level, the pitch of the slope and the skiing mode.

It has been stated this underestimation originates from a significant part of the force actually being transferred through the ski boot’s cuff. As a result, the CoP trajectory also tends to be underestimated along both the anterior-posterior (A-P) and medial-lateral (M-L) axes compared to force platforms.

Forces transferred through the cuff of a ski boot to the ski can limit or even prevent the inertia impulse loading associated with the Two Phase Second Rocker/Turntable Effect. In addition, forces transferred through the cuff of a ski boot to the ski intercept forces that would otherwise be transferred to a supportive footbed or orthotic.

Rocker Roll Over

In his comment to my post, OUTSIDE SKI BALANCE BASICS: STEP-BY-STEP, Robert Colborne said:

In the absence of this internal rotation movement, the center of pressure remains somewhere in the middle of the forefoot, which is some distance from the medial edge of the ski, where it is needed.

Rock n’ Roll

To show how the Two Phase Second Rocker rocks and then rolls the inside ski onto its inside edge at ski flat during edge change, I constructed a simple simulator. The simulator is hinged so as to tip inward when the Two Phase Second Rocker shifts the center of pressure (COP) from under the heel, on the proximate center of a ski, diagonally, to the ball of the foot.

The red ball in the photo below indicates the center of gravity (COG) of the subject. When COP shifts from the proximate center to the inside edge aspect, the platform will tilt and the point of COP will drop with the COG in an over-center mechanism.


A sideways (medial) translation of the structures of the foot away from the COG will also occur as shown in the graphic below. The black lines indicate the COP center configuration of the foot. The medial translation of the foot imparts rotational inertia on the platform under the foot.

Two Phase Second Rocker: The Movie

The video below shows the Two Phase Second Rocker.

Click on the X on the right side of the lower menu bar of the video to enter full screen.

The graphic below shows to Dual Plane Turntable Effect that initiates whole leg rotation from the pelvis applying multi-plane torque to the ski platform cantilevering reaction force acting along the running edge of the outside ski out under the body of the ski. A combination of over-center mechanics and internal (medial or into the turn) application of rotation of the leg from the pelvis, counters torques resulting from external forces.


  1. http://learn.parallax.com/tutorials/robot/elev-8/understanding-physics-multirotor-flight/inertia-momentum-impulse-and-kinetic
  2. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0176975

 

 

 

 

WHO NEEDS FOOTBEDS? NO ONE

There are some who can benefit from footbeds or orthotics and some who do actually need them. But these groups are the rare exception. And they are unlikely to be skiers.

Orthotics. The pros / cons of orthotics in today’s society!

In a recent YouTube video (1.), Podiatrist & Human Movement Specialist, Dr Emily Splichal, explores the concept of orthotics and their role in today’s society. Dr. Splichal doesn’t pull any punches when she says:

“…..I have been through the conventional podiatric school and been fed pretty much the bullshit from podiatry of how every single person needs to be in orthotics, that our foot is not able to support itself without orthotics……if we do not use orthotics our foot is going to completely collapse  and you are going to lose your arch…….”

“……Our foot is designed to support itself. If we actually needed orthotics, we would be born…..we would come out of the womb, with orthotics on our feet.”

Meantime, The Foot Collective  asks (2.) Are you promoting weak feet?

  • Anything you use for artificial support at the feet (footwear with arch support & orthotics) your brain takes into account and accommodates for it.
  • That means if you provide your foot support your brain shuts down the natural arch supporters to reduce un-necessary energy expenditure.
  • Stop using support to help with pronation and understand why your feet pronate in the first place – because they are weak.
  • Strong feet = strong foundation = strong body.

The Real Source of Support for the Arch

Ray McClanahan, D.P.M. offers a perspective on the issue of Arch Support in his post on the CorrectToes blog (3.)

Are Custom Footbeds and Orthotics better than stock insoles?

In his post of August 20, 2017, Custom Foot Orthotics; No Better Than Stock Insoles (4.), Rick Merriam, of Engaging Muscles, explores the issue of orthotics in depth.

Prior to being told that supportive insoles are the way to go, I think it’s safe to say that all of those people didn’t know what they didn’t know.

The erroneous assumption that every skier needs footbeds or orthotics was made at a time when little  was known about the function of the foot and lower limb, especially in late stance. I was one of those who didn’t know what I didn’t know when initially when down the ‘the foot needs to be supported in skiing’ road up until I realized what I didn’t know and took steps to acquire the requisite knowledge.

Footbeds; is anyone checking what they do?

In 2000, I formed a company called Synergy Sports Performance Consultants (5). Synergys’ product was high quality information. One of my partners, UK Podiatrist, Sophie Cox, was trained by Novel of Germany and was one of the few experts in the world at that time on the Pedar system. Synergy did not make and/or sell footbeds or orthotics. Instead, we checked the effect of footbeds on skier performance. We performed a quick footbed check for a minimal fee of $20 using the sophisticated Novel Pedar pressure analysis technology.

Synergy was one of the first companies in the world to use the Novel Pedar pressure analysis system synchronized to video to acquire data on skier performance and analyze the captured data.  The Synergy team with diverse expertise studied the effect of ski boots and custom insoles on skier performance and identified functional issues in the body that needed to be addressed. It was a common finding that custom footbeds were significantly compromising skier performance, especially the ability to create the necessary platform under the foot on which to stand and balance on the outside ski.

Synergy offered a comprehensive 5 Step Performance Program that started with a footbed check. A key component was item 2., the Biomechanical Check.

With increasing recognition of the negative effect of most footwear on the user and criticism of the unproven claims made for footbeds and orthotics coming hard and fast, credibility in skiing is rapidly going downhill. It is time for proponents of custom insoles for ski boots to support their claims with solid evidence, especially evidence supported with data acquired during actual ski maneuvers. The technology to do this has existed since at least the year 2000.


  1. https://youtu.be/CIRf9WHmMXI
  2. http://www.thefootcollective.com
  3. https://www.correcttoes.com/foot-help/articles-studies/arch-support/
  4. http://www.engagingmuscles.com/2017/08/20/custom-foot-orthotics/
  5. DIGITAL SALVATION FOR THE SOLE [BACK TO THE FUTURE] –  http://wp.me/p3vZhu-24g

SHOE/LINER HACKS

There is no point in continuing my discussion of the mechanics of balance on the outside ski because the odds are great that ski boots are preventing most skiers from engaging the mechanics required to apply the torsional forces to a ski with which to establish a balance platform under the outside foot.

In the scheme of things, an essential first step is to adapt the ski boots to functional needs of the skier as opposed to forcing the skier to adapt to the limitations imposed on them by the ski boots. Tightly fitting, supportive ski boots and most conventional constricting, cushioned, supportive footwear actually makes the feet weaker while compromising postural alignment and balance. There is an emerging global movement that is recognizing conventional footwear as THE problem behind compromised foot function while creating a ‘perceived need’ for cushioned soles  and artificial support in the form of custom insoles and orthotics which, instead of solving functional issues in the feet, lower limbs and entire body, further weaken the biokinetic chain.

The links below are to 3 articles that speak to this subject.

ORTHOTICS OR NOT => OUR LIMITING FOOT BELIEFS ARE HURTING US – http://kristinmarvinfitness.com/orthotics-or-not-our-limiting-foot-beliefs-are-hurting-us/

YOU WERE BORN WITH PERFECT FEET – https://www.correcttoes.com/foot-help/feet-101/

STRENGTHENING VS. SUPPORTING: THE COMPETING LOGIC OF FOOT HEALTH – https://www.correcttoes.com/foot-help/strengthening-vs-supporting-competing-logic-foot-health/

There is currently a whole series of Foot-Cast Episodes on The Foot Collective site at – http://www.thefootcollective.com

see – THE HUMAN GUIDEBOOK FOR SWITCHING TO BAREFOOT FOOTWEAR


A good starting point is to acquire a sense of how day-to-day footwear compromises foot and lower limb function and the modifications or ‘hacks’  necessary to adapt the footwear to the functional needs of the user.

A recent post on the Correct Toes blog called ‘How to Modify Your Shoes to Better Fit Your Feet’ (1.), comments on a runner who was experiencing distracting numbness and tingling in her feet, but balked at allowing her coach to make a few cuts in the upper material of her shoes to relieve the tension that was causing her problem. Most people are uneasy with the idea of modifying footwear. They tend to readily accept standard, off the shelf shoe size fit and assume that the way a shoe fits (or doesn’t) fit their foot is the way it is supposed to fit.

I recently had a similar experience with a young ski racer whose toes were crunched up in her ski boots that were both too short and too narrow. The liners were especially bad. Like many of today’s young racers, early in her racing career, she had probably grown accustomed to the constraint imposed on her feet by her ski boots and had unconsciously learned to make her feet comfortable by standing with most of her weight on her heels. After a time, her body had come to accept this as ‘normal’. Once this happened, she became reluctant to make changes.

A ex-racer, who I worked with back in the 1970s, loaned the young racer a pair of her boots. The improvement in the racer’s skiing was immediate and remarkable. Her coach commented that she had made 6 months improvement in one day! Unfortunately, stories of skiers and racers whose foot function, balance and even the function of their entire body has been compromised by tightly fitting, supportive ski boots is common. But happy outcomes, such as this young racer experienced, are exceedingly rare.

The Correct Toes post offers some good suggestions on footwear modifications that are remarkably similar to those I have used for decades in both ski boot liners and in my own footwear. The reason the modifications are similar is that the end objective; creating a functional environment for the user by minimizing the negative impact of the footwear on foot function, is the same.

The series of photos that follow illustrate examples of modifications that can improve the functional fit of footwear. An easy modification is to reconfigure the lacing pattern. Just because a shoe has a specific set of lace eyelets does not mean they all are necessary. The 2 photos below are from the Correct Toes article.

Photo with permission of Correct Toes

The photos below are the lace hacks I made on my Xero Prio (left) and Lems Primal 2 (R).

One modification that the Correct Toes article does not mention is the use of lace locks. Lace locks allow lace tension to be regulated and maintained without the need to over tighten laces to prevent them from coming undone.

This is one form of lace locks on my Xero Prio.

This is another form of lace locks on my Lems Primal 2.

I also use Correct Toes to improve foot function.

Correct Toes, The Foot Collective, EBFA, Feet Freex, EM Sports and many others are advancing on a uniform front in lock-step with the makers of minimal shoes in recognizing the damage caused to feet by conventional footwear while moving towards a uniform standard for the design and construction of footwear that creates a functional environment for the foot, while minimizing the negative impacts associated with structures placed on the human foot. Technologies such as NABOSO hold the promise of advancing on barefoot function in what I like to call ‘Beyond Barefoot’.

It has long been my experience that liners are the most problematic aspect of most ski boots. When I worked exclusively with Langes, I often made extensive modifications to liners that included using a liner a size larger than the shell size and re-sectioning and/or re-sewing the forefoot to allow proper alignment of the big toe and adequate width for the forefoot to fully splay.

The biggest problem in ski boot liners is in the toe box, especially the shape of the toe end in that it forces the big toe inwards, towards the center of the foot.

A modification that the Correct Toes article suggests is to make small slits on the side of the footwear opposite the point where the foot needs more room to splay.

Photo with permission of Correct Toes

Cutting small slits along the base of a ski boot liner is the first hack I usually try. But in many cases, I find more drastic modifactions are necessary in order to obtain the width required for the foot to fully splay and the big toe to align properly.

The photos below are before (L) and after (R) modifications that were necessary to accommodate my wife’s feet. These are older race stock Lange liners which I fit to her extensively modified Head boot shells.

The photo below is of the modified liner from my Head World Cup boot.

For ‘shallow’ feet or feet with a low instep the Correct Toes article suggests adding tongue depressors along the top of the foot or under the laces to help fill the void and prevent the foot from lifting or sliding around.Photo with permission of Correct Toes

The photo is of forefoot/instep retention pad that applies a constraining load to the foot that is substantially perpendicular to the transverse plane of the boot board. This device is similar to the one that powered Steve Podborksi to the podium in World Cup Downhill races. Today, Steve remains the only non-European to have ever won the World Cup Downhill title.

I devoted a large portion of my US Patent 5,265,350 to laying the groundwork for a functional standard that could evolve and eventually be applied to all forms of footwear, but especially ski boots. There are encouraging signs that the ski industry has finally started to take baby steps in this direction. I will discuss this in my next post.


  1. https://www.correcttoes.com/foot-help/modify-shoes-better-fit-feet/ 

NABOSO PROPRIOCEPTIVE STIMULATION INSOLES

For several weeks, I have been testing the first-ever small nerve plantar proprioceptive stimulation insole technology called NABOSO, which means “barefoot” in Czech. The surface science technology was invented by Dr. Emily Splichal and is being marketed by her in conjunction with NABOSO yoga mats and floor tiles.

Introducing Naboso Insoles by Naboso Barefoot Technology. Get ready to experience what it truly means to move from the ground up with the first-ever small nerve proprioceptive insole to hit the footwear industry.

The skin on the bottom of the foot contains thousands of (small nerve) proprioceptors, which are sensitive to different stimuli including texture, vibration, skin stretch, deep pressure and light touch. When stimulated these proprioceptors play an important role in how we maintain upright stance, activate our postural muscles and dynamically control impact forces. – Dr. Emily Splichal

http://nabosotechnology.com/about

Dr. Emily Splichal goes on to state:

The skin on the bottom of the foot plays a critical role in balance, posture, motor control and human locomotion. All footwear – including minimal footwear – to some degree blocks the necessary stimulation of these plantar proprioceptors. The result is a delay in the nervous system which can contribute to joint pain, compensations, loss of balance and inefficient movement patterns.

Naboso Insoles are backed by surface science and texture research – and have been shown to not only improve balance but also positively impact gait patterns, ankle proprioception and force production in athletes.

Dr. Splichal stresses that:

This (NABOSO insole) is an insole providing proprioceptive and neuromuscular stimulation – it is not an orthotic providing biomechanical control.

http://nabosotechnology.com/naboso-insoles/

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.

Dr. Splichal cites studies that found that textured insoles increased the activity of receptors in the plantar surface of the feet with a significant, immediate effect seen in the outcome measures of static (weight bearing) and dynamic (weight symmetry index, strength symmetry) in balance tests  as well as in gait symmetry (single support and swing phases). Thus, the proprioceptive stimulation benefit of textured insoles is carried over into footwear without textured insoles. I have noticed a significant improvement in  plantar proprioceptive sensitivity when barefoot or when my feet are not bearing weight. It is as if my feet have been put to sleep by a local anesthetic which has worn off.

Dr. Splichal’s information on NABOSO states that for the first time ever it is now possible to bring the power of barefoot science and plantar proprioceptive stimulation to all footwear – regardless of support, cushion or heel toe drop.

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. I have experienced the best results with NABOSO in the Xero Prio shoe with the Lems Primal 2 and a Vivobarefoot model, close seconds.

The photo below shows the Xero Prio (blue-grey) with the Lems Primal 2 (black).

Both shoes have thin soles with low resiliency (the material compresses very little). The soles are also very flexible, an important quality. The sole wearing qualities of the Xero are excellent. The Xero Prio has become my all around minimal shoe. I use it for cycling on my mountain bike fit with large flat platform pedals.

The photo below is of the NABOSO insole for my left shoe.

Initially, NABOSO insoles are perceived, but not uncomfortable. After a time, shoes feel strange without them.

Over several weeks, I have done many tests of different shoes and insoles where I compare cushioned, standard insoles to NABOSO and different shoes with and without NABOSO as well as one-on-one comparisons with different shoes on each foot. After an initial walk in period, if I remove a NABOSO insole from one of my Xero Prios, it feels as if sole of the foot with the Xero without the NABOSO is signicantly less sensitive.

The most significant aspect of trying NABOSO insoles in different shoes is that it immediately becomes apparent just how bad some shoes are. The more cushioning, the narrower the fit and the greater the heel to toe elevation of the sole, the worse the shoe feels. For example, when I compared the Xero Prio with zero drop to a Nike Free with a 5 mm drop, I immediately sensed a pronounced negative effect on my posture and muscles of my legs, especially my glutes.

A Game Changer?

Prior to NABOSO, footwear companies could make shoes that have a negative affect on posture, balance and gait because it could be argued that the benefits of protecting the soles of the feet from mechanical damage outweigh any negative effects on balance and increased susceptibility to falls and injury. But the criteria for product liability is that a product must minimize, but not necessarily eliminate, the risk of injury to the consumer. Studies of textured insoles and even thin, low resilency soled footwear have shown dramatic improvements in balance and gait while reducing the risk of falls and potential injury. The inescapable conclusion is that footwear that reduces balance and the efficiency of gait while increasing the risk of falls and potential injury fails to meet this standard. This raises the question, “Will product liability litigation in footwear be the “next shoe to drop?””

NABOSO in  Ski Boots?

I have not yet had an opportunity to test NABOSO ski boots. But 2 racers I am working with are using NABOSO in zero drop minimal shoes. Stay tuned.

 

THE MECHANICS OF BALANCE ON THE OUTSIDE SKI: WINDLASS POWER

Two factors can prevent a skier from being able to develop a platform under the body of the outside ski on which to stand and balance on during a turn using the same processes used to balance on one foot on solid ground:

  1. The biomechanics of the foot and leg have been compromised by traditional footwear and,
  2. The structures of the ski boot, especially insoles, footbeds, orthotics and form fit liners, are interfering with the foot to pelvic core tensioning of the biokinetic chain that starts in the forefoot.

The torsional stiffening of the ankle and knee joints resulting from fascial tensioning of the biokinetic chain is fundamental to the ability to create a platform under the body of the outside ski by internally rotating the outside leg from the pelvis. It may sound complicated. But it is actually quite simple. Once learned, it can become as intuitive as walking.

The best method I have found to appreciate how ski boots, custom insoles and form fitting liners can affect the function of the feet and even the entire body, is do a series of exercises starting with the short foot. The short foot helps to assess the ability to harness the Windlass Power associated with the big toe. Once proper function has been acquired in the foot and leg, a skier can go through a methodical, step-by-step process to assess the effect of each component of the ski boot on the function of the feet and legs.

The latest edition of Runner’s World (1.) reports on a study done by a team at Brigham Young University that compared the size and strength of the foot’s “instrinsic” muscles in 21 female runners and 13 female gymnasts. Gymnasts train and compete in bare feet.

The researchers found:

Of the four muscles measured with ultrasound, the gymnasts were significantly bigger on average in two of them, with no difference in the other two. The gymnasts were stronger in their ability to flex their big toe, with no difference in the strength of the second, third, and fourth toes.

Although balance is important in all sports, it is especially critical in gymnastics. So it is significant that study found that the big toes of the gymnasts were stronger than the big toes of the runners.

Until recently, I found it much easier to balance on my left leg than my right leg. The big toe on my left foot was noticeably larger than the big toe on my right foot and the big toe on my left foot was aligned straight ahead whereas the big toe on my right foot was angled outward towards my small toes. This misalignment had pushed the ball of my foot towards the inside of my foot causing a bunion to form on the side, a condition known as hallux valgus. I now understand why I could balance better on my left foot than my right foot.

The muscle that presses the big toe down is called the Flexor Hallucis Longis (FHL). It is inserted into the last joint of the big toe where it exerts a pull that is linear with the big toe and ball of the foot. When the arch is maximally compressed in late stance, the Flexor Hallucis Longis is stretched and tensioned causing the big toe to press down. It’s insertion on the upper third of the fibula causes the lower leg to rotate externally (to the outside). When stretched, the FHL acts in combination with the Posterior Tibialis to support the arch. Footwear that prevents the correct alignment of the hallux weakens the arch making it more difficult to balance on one foot; the foot pronates unnaturally.

Going mostly barefoot for the past 10 years and wearing minimal type shoes for the past 6 years, made my feet stronger.  But it had minimal effect in correcting the hallux valgus in my right foot. It was only after doing the exercises in the links that follow, such as the short foot, that the big toe on my right foot became properly aligned and grew in size. It is now the same size as my left toe and I am able to balance equally well on both feet. The problem with ski boots and most footwear, is that they can force the big toe into a hallux valgus position while preventing the forefoot from splaying and spreading naturally weakening the arch and significantly impairing natural balance.

In the early 1970’s, when the then new plastic ski boots were making a presence in skiing, research on human locomotion was in its infancy. Studies of the effects of sports shoes on human performance were virtually nonexistent. The only technology available back then with which to study the biomechanics of athletes was high speed (film) movies. Ski boot design and modification was a process of trial and error. Many of the positions that predominate even today were formed back then.

As methodologies began to develop that enabled the study of the effect of sports shoes on users, biomechanists and medical specialists became convinced that excessive impact forces and excessive pronation were the most important issues affecting performance and causing or contributing to injury. I suspect that biomechanists and medical specialists arrived at this conclusion even though there was little evidence to support it because it seemed logical. Soon, the term, excessive pronation became a household word. The perceived solution? Arch supports, cushioned soles, motion control shoes and a global market for arch supports.  This appears to have precipitated an assumption within the ski industry that the feet of all skiers needed to be supported in ski boots and pronation, greatly restricted, or even prevented altogether. Even though no studies were ever done that I am aware of that demonstrated that pronation was a problem in skiing, support and immobilization became the defacto standard. Custom footbeds, orthotics and form fitted liners became a lucrative market.

As the support and immobilize paradigm was becoming entrenched in skiing, studies were increasingly concluding that, with rare exceptions, excessive pronation, is a non-existent condition with no pathologies associated with it and that the role of impact forces was mis-read. Today, it is increasingly being recognized that interference to natural foot splay and joint alignment of the big toe by the structures of footwear, causes weakness in the foot and lower limbs through interference with the natural processes of sequential fascial tensioning that occurs in the late stance phase. But the makers of footwear and interventions such as arch supports, have been slow to recognize and embrace these findings.

A key indicator of whether a skier has successfully developed a platform under the outside ski with which stand and balance on, is the position and alignment of the knee in relation to the foot and pelvis as the skier enters the fall line from the top of a turn. I discuss this in my post, MIKAELA SHIFFRIN AND THE SIDECUT FACTOR.

Best Surfaces for Training

A good starting point for the short foot and other exercises is Dr.Emily Splichal’s YouTube video, Best Surfaces for Training https://youtu.be/gvJjIi3h1Bs

Although it may seem logical to conclude that soft, cushioned surfaces are best for the feet, the reality is very different. The best surfaces to balance on are hard, textured surfaces. Dr. Splichal has recently introduced the world’s first surface science insoles and yoga mats using a technology she developed called NABOSO which means without shoes in Czech.

The skin on the bottom of the foot plays a critical role in balance, posture, motor control and human locomotion. All footwear – including minimal footwear – to some degree blocks the necessary stimulation of these plantar proprioceptors resulting in a delay in the response of the nervous system which can contribute to joint pain, compensations, loss of balance and inefficient movement patterns. I’ve been testing NABOSO insoles for about a month. I will discuss NABOSO insoles in a future post. In the meantime, you can read about NABOSO at https://naboso-technology.myshopify.com/products/naboso-insoles

Short Foot Activation

 

Short Foot Single Leg Progressions


  1. Here’s the Latest Research on Running Form – May 30, 2017
  2. Biomechanics of Sports Shoes – Benno M. Nigg

THE MECHANICS OF BALANCE ON THE OUTSIDE SKI: PRESS AND POINT THE BIG TOE

A widespread perception appears to exist within the skiing community is that the ability to hold a ski on edge by using the leg to exert force against the side of the stiff shaft of a ski boot and staying upright and not falling, equates with good balance. This ingrained perception presents a challenge in terms of communicating how the world’s best skiers create a platform under the body of the outside ski that they can stand and balance on using the same processes that we all use to stand and balance on a hard, flat level surface.

Last ski season, I developed simple cue to help skiers find the right mechanics and biomechanics as the new outside ski goes flat between edge change and then rolls into the turn on its new inside edge.  At ski flat, if a skier has the right stance, they should feel strong pressure under the ball and the big toe. As the skier extends and inclines into the new turn, the outside leg should be rotated into the turn to point the big toe in the direction of the turn. Hence the cue, press and point the big toe.  This pressure under the ball of the foot and big toe should be maintained through the turn phase until it is released by the transfer or weight to the inside (uphill) ski at the start of the transition to the inside. The strong pressure under the ball of the foot and the force that presses the big toe down flat is passively created by a strong stance, not conscious effort.

The Reverse Windlass

The pressure under the big toe is created by what is called the Reverse Windlass Mechanism. This naturally happens in the late phase of stance when walking barefoot. But wearing shoes with raised heels and cushioned insoles makes it impossible for the Reverse Windlass to function. When the Reverse Windlass is lost, it must be re-acquired by being barefoot as much as possible and walking, running and training in zero drop, thin soled minimal shoes. In some cases, people have to learn to walk naturally by rehearsing the action.

There is an excellent YouTube video by Teodoro Vazquez on Blog del Runner  called Windlass Mechanism and Running Biomechanics – https://youtu.be/y_8SrufgmDk. Vazquez describes the 3 phases of the windlass mechanism, Active (Activo), Reverse (Inverso)  and Passive (Pasivo). Although the video is directed at running, the primary concepts have direct application to skiing and ski technique. The reverse windlass is activated by the weight as shown in the graphic below from Vazquez’s YouTube video.
 This tensions the arch of the foot and presses the big toe down.
As the shank angle increases, the soleus muscle goes into isometric contraction and arrests further shank movement. The results in a heel to forefoot rocker action that dramatically increases the down force under the ball of the foot and the big toe. What I call the Spinal Reflex or SR Stance maximizes the down forces.

It is important that when the big toe (aka Hallux) is pressed down flat, the ball of the foot and big toe feel like one. When the big toe is pressed down properly, you should feel your glutes tighten. The leg you are standing on should be straight and the knee pointed straight ahead.

An important muscle in the Reverse Windlass is the Flexor Hallucis Longis or FHL. When the soleus goes into isometric contraction, the FHL is tensioned. This stabilizes the foot and knee by rotating them away from the center line of the body.

Things that prevent the Reverse Windlass

1. A condition called Hallux (big toe) Valgus
2. Narrow shoes and especially shoes with a pointed toe box.
3. Ski boots, especially ski boot liners.
4. Shoes with elevated heels, cushioning and toe spring (toes raised up). Note: A small amount of ramp angle is necessary for the SR Stance.
5. Footbeds and Insoles.
In my next post, I will discuss fixes to enable and/or restore the Reverse Windlass.

INTRODUCING THE FOOT COLLECTIVE

The Skier’s Manifesto places a high priority on foot function and exercises that make feet strong and healthy. (THE IMPORTANCE OF STRONG HEALTHY FEET IN SKIING).  There is a rapidly emerging camp of medical professionals and trainers aligned with this cause who offer excellent articles on this subject. One such group is TheFoot Collective – http://www.thefootcollective.com.

TheFoot Collective has kindly given me permission to repost material from their blog on the Skier’s Manifesto. The graphic below is from the home page of TheFoot Collective.

What is the Foot Collective?

The Foot Collective is a group of Canadian physical therapists giving people back control over the health of their feet through education. Most modern day humans have poorly functioning feet and our mission is to spread the truth about footwear and give people the information needed to independently restore their own feet.

The collective exists to spread awareness of the importance of foot health and to provide quality advice on restoring proper foot function.

Foot problems have reached epidemic levels and the solution is simple: Quality foot health education to help people fix their own feet.

There’s a big problem with modern footwear

The modern shoe is harming the human foot. Footwear companies are creating products to make money, not in the interest of foot health and its slowly killing our feet. We’re here to spread the truth about footwear.

Most footwear today has an elevated heel, narrow forefoot and a slab of foot numbing cushioning between your foot and the ground below you.

Your feet are magically designed body parts with the primary purpose of sending your brainsignals about the ground below you. When they get compressed and are prevented from sensing the ground because of cushioning, they lose their ability to function and create nasty upstream effects for our bodies.


The kind of shoes you wear daily, especially the type of shoe you train in, affects how your body functions in skiing. Cushioning and cushioned insoles are especially bad. This is a recent post on the TheFoot Collective.

THE DANGER OF HEELED FOOTWEAR
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wearing a shoe with an elevated heel might seem harmless but it has real effects on your posture upstream. These postural changes change how your body moves by making certain muscles more dominant (quads especially) and others weak (glutes)
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Over time, heeled footwear is a big culprit for knee problems and tight ankles so avoid them whenever you can. Finding a zero drop flat shoe can be quite difficult but taking the time to find one makes a massive difference in your joint health and movement patterns
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Most modern day running shoes and dress shoes have this nasty heel lift so beware of the consequences and transition to zero drop barefoot footwear. Your body will thank you
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I have been testing different brands of minimal shoes; zero drop, thin flexiable, low resilency soles, for the past few months and will posting on this issue soon. For reasons I will explain in future posts, it appears as if a small amount of positive toe down ramp (aka drop) – approximately 2.5 degrees, is important to a strong stance in skiing. But my regular footwear is all minimal, zero drop.