CARV

THE MECHANICS OF BALANCE ON THE OUTSIDE SKI: GLUTE POWER EDGE CONTROL

The New Year started off on a positive note with a great post on preventing sports injuries by Rick Merriam; Engaging Muscles (1.), a new YouTube video by LaGrandNeve (2.) on the importance of the feet in skiing and the long anticipated delivery of the CARV system.

In his post on preventing sports injuries, Merriam, cuts right to the heart of the matter when he states:

Sadly, most professional athletes don’t even know what it feels like to have muscles pulling at the right time.

Said another way, most professional athletes haven’t experienced what it feels like to perform with more stability throughout their chain.

By chain, Merriam is referring to the biokinetic chain.

My consistent finding over the years has been that most skiers, even racers at the World Cup level, don’t know what a stance founded on a strong, stable biokinetic chain should feel like. Even among those who have skied for decades, many have never experienced it. And the role of muscles is rarely, if ever, mentioned in discussions of ski technique or analysis of technique.

In Corso di sci Check Point 2018 – 03 (2.); Piedi cerca spigolo (Feet looking for corner) Valerio Malfatto states:

Contrary to what is believed in the curves with the skis the feet are very important we see how and why.

At about 1’50” into the video, Malfatta begins to draw a series of sketches. The first sketch appears to show how eversion of the foot puts the outside ski on edge by creating a flow of force into the turn. He appears to acknowledge how the ski and foot can either rotate to the outside of a turn (outside foot/ski inverts) or the inside of a turn (outside foot/ski everts). Then he appears to be showing how pressure applied under the ball of the outside foot rotates the ski onto it’s inside edge. Since I understand very little spoken Italian, it would be helpful if a follower of my blog who speaks Italian could post a comment explaining what Malfatto is saying in his video. My apologies to Malfatto if I have misinterpreted his graphics.

The graphic below is a screen shot from Malfatto’s video that shows how the foot and ski have rotated into the turn by pressure applied under the ball of the outside foot.

Although I have seen examples in that suggest rolling the ankles of the feet into a turn will apply edging forces, Malfatto’s video is the first example I have seen that appears to recognize that the outside foot and ski of a turn will tend to invert (rotate downhill) in the load phase under the force applied by the weight of the skier in the absence of a countering eversion torque.

While elite skiers and racers are usually aware of pressure felt under the ball of  the outside foot, it is difficult to replicate the feel in a static environment. So static exercises are often employed in an attempt to demonstrate what the skier is doing.

At about 5’30” into Malfatto’s video there is a dryland demonstration of the outside foot of a turn being rotated into the turn by contracting the muscles that evert the foot while the inside foot is rotated into the turn by contracting the muscles that invert the foot. There are a number of problems associated with attempting to hold skis on edge by contracting the inverter and everter muscles:

  • The muscles are in concentric contraction; i.e. they are physically shortening.
  • Both muscles are extensors of the ankle; i.e. as they shorten, they will plantarflex the ankle. This will shift the weight of the skier back under the heel, pushing the skier into the back seat.
  • The use of muscles to evert and invert the feet require conscious effort in what is called Executive Control. The processing rate of the brain in this mode is limited to about 60 bits per second compared to that of processing in Automaticity (subconscious control) which is about 11 million bits per second.
  • Both muscles are relatively weak compared to the glutes and soleus which are among the most powerful muscles in the human body.
  • Neither the everters or inverters cross the knee joint.

At the time that I wrote United States Patent 5,265,350 in February of 1992, I described the lack of knowledge of the complex biomechanics of the human muscle-skeletal system as it relates to the interaction of the foot with footwear such as skates and ski boots. In consideration of this, I made a concerted effort to provide as much information as possible to those knowledgeable in the field with the objective of advancing the state of knowledge on the subject. Since the writing of my patent my knowledge has evolved and continues to do so.

The following statements are excerpted from my patent.

The most important source of rotational power with which to apply torque to the footwear is the adductor/rotator muscle groups of the hip joint. In order to optimally link this capability to the footwear, there must be a mechanically stable and competent connection originating at the plantar processes of the foot and extending to the hip joint. Further, the balanced position of the skier’s centre of mass, relative to the ski edge, must be maintained during the application of both turning and edging forces applied to the ski. Monopedal function accommodates both these processes.

As a result of the studies done in 1991 with the research vehicle called the Birdcage, I had come to recognize the importance of a mechanically stable and (physically) competent connection extending from the plantar processes of the foot to the hip joint to facilitate the power of the glutes for balance and edge control.

Yet a further problem relates to the efficient transfer of torque from the lower leg and foot to the footwear. When the leg is rotated inwardly relative to the foot by muscular effort, a torsional load is applied to the foot. Present footwear does not adequately provide support or surfaces on and against which the wearer can transfer biomechanically generated forces such as torque to the footwear. Alternatively, the footwear presents sources of resistance which interfere with the movements necessary to initiate such transfer. It is desirable to provide for appropriate movement and such sources of resistance in order to increase the efficiency of this torque transfer and, in so doing, enhance the turning response of the ski.

Precise coupling of the foot to the footwear is possible because the foot, in weight bearing states, but especially in monopedal function, becomes structurally competent to exert forces in the horizontal plane relative to the sole of the footwear at the points of a triangle formed by the posterior aspect and oblique posterior angles of the heel, the head of the first metatarsal and the head of the fifth metatarsal. In terms of transferring horizontal torsional and vertical forces relative to the sole of the footwear, these points of the triangle become the principal points of contact with the bearing surfaces of the footwear.

A control point in the form of a counter set medial to the head of the first metatarsal is used in order to restrain the first metatarsal against medial movement, such as would occur when internal torsional force is applied to the foot.

In skiing, the mechanics of monopedal function provide a down force acting predominantly through the ball of the foot (which is normally almost centred directly over the ski edge). In concert with transverse (into the turn) torque (pronation) arising from weight bearing on the medial aspect of the foot which torque is stabilized by the obligatory internal rotation of the tibia, the combination of these forces results in control of the edge angle of the ski purely as a result of achieving a position of monopedal stance on the outside foot of the turn.

The edge angle can be either increased or decreased in monopedal function by increasing or decreasing the pressure made to bear on the medial aspect of the foot (turntable rotation) through the main contact points at the heel and ball of the foot via the mechanism of pronation. As medial pressure increases (by glute torque), horizontal torque (relative to the ski) increases through an obligatory increase in the intensity of internal rotation of the tibia. Thus, increasing medial pressure on the plantar aspect of the foot tends to render the edge-set more stable. The ski edge-set will not be lost until either the state of balance is broken or the skier relinquishes the state of monopedal function on the outside ski.

The skiers demonstrating the use of the feet to apply edging forces to the skis at 5’30” in the LaGrandNeve video (2.) clearly show the skiers engaging the second rocker by impulse loading the outside foot and ski and then rotating the outside leg into the turn as they exit the fall line and enter the load phase.

The graphic below shows the device I designed and constructed to train skiers and racers in the movement and muscle patterns required to enable the power of the glutes to be engaged to establish a balance platform under the outside ski and control edge angle as described in my post THE MECHANICS OF BALANCE ON THE OUTSIDE SKI: CLOSED CHAIN OUTSIDE LEG ROTATION. Two forces acting together are required to to create the mechanics that rotate the outside ski on it’s inside edge into the turn.

  1. The center of the weight applied by must be under the ball of the foot and,
  2. Rotational force must be applied to the medial (inner) aspect of the ball of the foot in what I described as Rocker TurnTable Rotation (4.).

If the center of the weight of the body W lies on the anatomical center axis of the foot (under the heel), it will act to oppose turntable rotation applied to the foot by the glutes.

In my next post, I hope to have data from CARV showing the loading pattern that enables the use of Glute Power for edge control.


  1. https://www.engagingmuscles.com/2018/01/01/prevent-injuries/
  2. https://youtu.be/aAJSqzcxrS0
  3. https://wp.me/p3vZhu-2cC
  4. https://wp.me/p3vZhu-2bb

THE SHOCKING TRUTH ABOUT POWER STRAPS REVISITED

Since I started this blog with my first post, A CINDERELLA STORY: THE ‘MYTH’ OF THE PERFECT FIT (1.) on 2013-05-11, THE SHOCKING TRUTH ABOUT POWER STRAPS (2.) is by far the most widely viewed post. This is significant because the content of this post challenges premises that are widely embraced and cited as knowledge that is fundamental to skiing.

The greatest enemy of knowledge is not ignorance; it is the illusion of knowledge.

                                                                                    – attributed to Stephen Hawking

Widely accepted false beliefs can negate incentives to pursue the acquisition of knowledge necessary to understand complex issues that fall outside the limits of established paradigms. A prime example being the ability to balance perfectly on the outside ski.

Observing great skiers like Marc Giardelli or Ingemar and more recently, Mikaela Shiffrin, Lindsey Vonn and Marcel Hirscher balance perfectly on their outside ski suggests it is possible. But uninformed observation in itself does not impart, let alone lead to, an understanding of the associated mechanics, biomechanics and physics of perfect balance on the outside ski as it equates with neuromuscular mediated dynamic balance of triplanar torques acting across the joints of the ankle/foot complex, knee and hip. The intrinsic need of those who regarded as authorities on ski technique to provide plausible explanations for the actions of elite skiers led to the fabrication of terms such as knee angulation that served to create an illusion of knowledge of the mechanism of balance on the outside ski. Knee angulation also provided an effective mechanism with which to demonstrate the mechanics of edge hold.

To raise new questions, new possibilities, to regard old problems from a new angle, requires creative imagination and marks real advance in science.

                                                                                                                          – Albert Einstein

While knee angulation provides a plausible explanation for a mechanism with which to rotate a ski onto it’s edge, it does not explain the mechanism of perfect balance on the outside ski in accordance with Newton’s Laws and the principles of functional anatomy. Solving this mystery required raising new possibilities and creating a new paradigm; one that looked at the function of the human lower limbs from a new perspective with new possibilities.

It took me from 1980 to 1990 to discover how the mechanism of balance on the outside ski works. Trying to impart an understanding of this mechanism to others has presented significant challenges because the illusion of knowledge within the ranks of the ski industry has resulted in a hardened mental model that makes the real mechanism all but invisible. The resulting information bias causes people to seek information that supports what they believe while filtering out information that conflicts with what they believe; i.e.

I don’t need new information on how to balance perfectly on my outside ski because I have been doing this for years and I don’t need to know anything more.

But the reality is, that with rare exception, while elite skiers and even World Cup racers may think they can balance on their outside ski they have no way of recognizing the correct feeling, let alone confirming that they are actually doing what they think they are doing.

I have designed and fabricated a device with which to train skiers/racers to create a platform under their outside ski on which to stand and balance perfectly on. The device can be used to capture what I call a skier’s personal Balance Signature using technologies like CARV. More on this in my next post.


  1. https://wp.me/p3vZhu-p
  2. https://wp.me/p3vZhu-UB

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

THE MECHANICS OF EDGE CHANGE

Comments made by followers of my blog suggest that significant confusion exists 0n the meaning of terms and representations of mechanics, biomechanics and physics used in typical explanations of ski technique and ski mechanics. In particular, there appears to be confusion between pressure and the representation of point forces.

Pressure is a physical force applied to an object that is distributed over the surface of the object.

Center of Pressure or COP is the point center of ground reaction force opposing a corresponding center of applied force acting on a object supported on the ground or a stable surface that acts in the capacity of ground in terms of providing a source of reaction force.

Torque or Moment of Force results from an offset between the centers of opposing physical forces acting on either side of an object.  This offset results in a torque or moment arm that tends ti create rotation about a center. When one force has a greater magnitude than the other force, rotation of the object will occur around the point of rotation.

Why typical balance explanations of skier balance are wrong

Balance in skiing is often depicted as a simple alignment of opposing point forces, usually a resultant force R acting in opposition to a snow reaction force S. The mechanics that make the edges of a ski grip are often shown as a simple alignment of opposing forces acting a single point on the edge. Explanations of this nature are physically impossible. What the authorities in skiing seem to conveniently be ignoring is the fact that pressure is applied by the snow along the entire running surface of the edge in contact with the the snow while an opposing area of pressure applied by the weight of the skier is acting on the body of the ski with an offset between the two centers of pressure. The authorities in skiing also seem to conveniently ignore what is arguably the key even in establishing a platform under the outside ski for the skier to stand and balance on, edge change.

Mikaela Shiffrin’s Get Over It drill on the Burke Mountain YouTube site makes a good segue to an explanation of the Mechanics of Edge change in the my next post – https://youtu.be/Bh7KF49GzOc

Bridget Currier is the model every skier should aspire to. She perfectly executes what I call the skimove. The skimove engages the external forces at ski-flat/edge-change to drive multi-plane torques acting about her outside ski into the turn while setting up a solid platform under her outside foot for her to stand on. Magnificent! This video should have at least a million views.

My comment from 2 years ago

Note carefully Currier’s stance in balance on her new outside ski, in particular, the angle of her torso with the snow. This is key to loading the ball of her outside foot.

Note carefully Shiffrin’s comment to move forward onto her new ski and how she used to think the movement was a lateral (sideways) move.

Most important of all – Patient Initiation. The reason? Shiffrin and Currier, don’t tip their outside ski on edge. They rock it on edge with a rocker impulse loading mechanism. The sequence is Rock, Roll n’ Rotate then Rotate the outside leg.

FEATURE POST: THE EMERGING REVOLUTION UNDERFOOT

There is a rapidly emerging convergence of electronic wearable technologies such as CARV, in ski boot digital sensor technology, and sport performance equipment. This years ISPO dedicated a large space to this segment with the larger mobile phone companies all showing concepts and apps.

There is a similar convergence emerging on the science front with attention increasingly focussed on the human foot as rapidly evolving micro-sensor technologies allow the study of metrics associated with foot function such as arch height and specific muscle activity. These technologies enable users to look inside footwear and study its effect on the foot that have previously been hidden out of sight and free from investigation and scrutiny. In due time, some of the premises that form the cornerstone of knowledge in skiing, such as the foot functions best in skiing when its joints are immobilized in a ski boot and, the ski boot is a handle that is used to apply force to a ski, will be scrutinized, revealed and discredited as fabricated nonsense.

THE EMERGING REVOLUTION UNDERFOOT

CARV IN BOOT DIGITAL SENSOR TECHNOLOGY

CARV – The world’s first wearable that helps you ski better. – https://carv.ai

Notch – 3D Motion Sensor Technology captures movements and shares and replays them in 3D in any modern browser – https://wearnotch.com

The equivalent of DNA, as an investigative tool with which to study the effects of footwear on the human foot, has arrived.