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

2 comments

  1. Dear David
    Thanks for your posts. I appreciate the practical nature of your suggestions to improve foot function and develop your cue press and point the big toe.
    To my regret, I only partly understand your analysis of the role of sidecut altering the ground reaction force analysis.
    In your post Michaela Shiffrin and the side cut factor you say “Except Platform Angle explanation won’t work because the piste is so hard that even the sharp edges of Shiffrin’s outside ski are barely penetrating the surface of the snow. So there can be no platform angle under the whole ski.” You also mention in your post THE MECHANICS OF BALANCE ON THE OUTSIDE SKI: WHERE IS GROUND? “that there can not be a point the point application of applied force in opposition to a point application of GRF as depicted in the right hand graphic above is a physical impossibility.” Can you explain again what is happening ?
    Thanks
    Mike

    1. Hi Mike,

      I apologize for the delay in responding to your comment.

      I only partly understand your analysis of the role of sidecut altering the ground reaction force analysis.
      > As Benno Nigg and others have pointed out, many of the assumptions that form the pillars of what is regarded today as knowledge in skiing were made prior to the existence of technologies that allow in vivo studies of human movement, particularly activities like skiing that involve dynamic, 3-dimensional forces. Concepts such as the use knee angulation to hold the skis on edge from a static postion across the slope of a ski hill were readily accepted without critical review probably because they created the perception that stiff boots that allow the legs to be used as levers, made skiing easy as did holding both skis on on their uphill edge while moving slowly down a slope and allowing the sidecut to self turn the skis. These flawed concepts created an information bias that distracted attention away from issues such as skier balance.

      A key event that seems to have escaped scrutiny is the overthrow mechanics associated with edge change. Lito Tejada-Flores called this roll over. I am facing several challenges in trying to bring my discussion of the mechanics of balance on the outside to a conclusion that is easily understood. One issue is the apparent widespread perception that the ability to hold both skis on using the legs to apply force to the shafts of the ski boot equates with balance. In this context, the events of ski flat between edge change are irrelevant.

      Another issue is my consistent finding that the skiers who have approached me for assistance are unable to perform the requisite bio-mechanics because their ski boots are preventing them from doing so. Correcting this situation has required up to 2 years because preventing the biomechanics and associated neural activity has embedded executive control in place of automaticity. In other words, the ski boots have forced the skier to think about an extremely complex neural muscular activity by using executive control which is not slow, but overwhelms the human brain. In a future post, I will discuss why ski teaching and coaching methodologies fail because they are predominantly executive control based in nature. In the meantime, I have provided a link to a paper you may find interesting. The subject is applicable to skiing.

      Automaticity of walking: functional significance, mechanisms, measurement and rehabilitation strategies
      Front. Hum. Neurosci., 05 May 2015 | https://doi.org/10.3389/fnhum.2015.00246
      David J. Clark1,2*1Brain Rehabilitation Research Center, Malcom Randall VA Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL, USA, 2Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA

      http://journal.frontiersin.org/article/10.3389/fnhum.2015.00246/full

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