Footwear science posts

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
👣👣
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)
👣👣
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
👣👣
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
👣👣


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.

CARVE, MEET BIRDCAGE – BIRDCAGE, MEET CARV

July 1991: Birdcage Research Vehicle – Cost approximately $140,000

Secret  Toshiba Prototype Portable Computer used for Birdcage studies – Value? Priceless!

Birdcage Co-Designer and Team Science Leader, Alex Sochaniwskyj, P. Eng.

After interviewing a number of candidates in the spring of 1991 for the science component of the MACPOD project to develop a ski boot based on anatomical principles, I chose Alex Sochaniwskyj, P. Eng. as the most qualified candidate and one of the most intelligent and creative persons I have ever had the privilege of meeting.

Alex provided the CV that follows in his letter in support of my nomination for the Gold Medal in the categories of Applied Science and Engineering in the 1995 British Columbia Science & Engineering Awards.

Alex Sochaniwskyj, P. Eng.

Alex is a professional engineer with 12 years of biomedical and rehabilitation engineering research experience in the Human Movement and Motor Functions Research Programmes at the Hugh MacMillan Rehabilitation Centre in Toronto, Ontario, Canada. The principle aim of these labs is to provide detailed information and objective analysis of movement, dynamics and motor function of persons with various physical disabilities. The information is used to objectively assess the effects of a variety of therapeutic and surgical interventions.

Alex holds a Bachelor of Science degree from the University of Toronto in Human Physiology and a Bachelor of Applied Science from the University of Toronto. Most recently, Alex has worked with several companies including ADCOM ELectronics Limited in Toronto, where he was responsible for the design and development of video conferencing and multi-media communication systems, and the Arnott Design Group, where he focused on physiological human factors in product system design, prototyping and testing.

Currently, as a principal at designfarm inc., he consults to design and manufacturing firms on the development of programs to evaluate human physiological, biomechanical, ergonomic and environmental response for product and interface design, and the planning of comprehensive technology implementation strategies for the integration of computing, telecommunication and telepresence technologies. Alex is also a Certified Alias Instructor in the Information Technology Design Centre in the School of Architecture and Landscape Architecture at the University of Toronto, where he teaches courses in computer literacy, three-dimensional design, modelling, simulation and animation.

Alex is a member of the Association of Professional Engineers of Ontario (APEO), the Institute of Electrical and Electronics Engineers (IEEE), the Association of Computing Machinery (ACM) and the University of Toronto, Department of Rehabilitation Medicine Ethics Review Committee. He is co-author of numerous publications in refereed medical and engineering journals and has produced several video productions regarding biomedical and rehabilitation engineering.

              – March 24, 1995

Team Birdcage


2000 – Novel Pedar In-Shoe pressure technology used by Synergy Sports Performance Consultants – Cost, approximately $60,000 with 2 Sony VAIO laptop computers

 


2017 – CARV: Cost? Approximately $300 US – See footnote re special price

 

Birdcage to CARV: “Where have you been? I’ve been waiting 26 years for you. Welcome! The future of skiing has arrived.”


FOOTNOTE
CARV is currently taking pre-orders at $249 at 
 http://carv.ai

OFF SEASON POST ACTIVITY

With ski season coming to an end in many parts of the world, I am going to start posting on what I have learned over the past ski season and changes that can be made to components such as the boot board (aka Zeppa) to improve performance and why how these changes work. I am also going to post on the implications on skiing of recent studies as well as the application and impact of technologies such as CARV and Notch. If these products become available soon enough, I plan to some testing before next ski season so I can write posts on how these technologies can be used to improve ski technique and technical analysis as well as identify problems caused by ski boots.

For the time being, I have decided to hold off on discussing the rocker impulse loading mechanism of the mechanics of balance on the outside ski because limitations imposed by the ski boot prevent the majority of skiers from generating the high transient impulse load within the 2 millisecond window that occurs during roll over through ski flat during edge change (see THE MECHANICS OF BALANCE ON THE OUTSIDE SKI: TIMING OF EDGE CHANGE) that is required to engage the mechanism that enables a skier to balance on the outside ski.

For academics, researchers and others with an interest in the science aspect of the design of ski equipment and the formulation of ski technique, I will be posting studies that have application to both.

WHY THE OPTIMAL STANCE FOR SKIING STARTS IN THE FEET

In this post, I am going to discuss why the optimal stance for skiing is dependent on the loading sequence of the new outside foot of turn, how this must start in the transition phase and why it is critical to the rocker impulse loading mechanism that engages the shovel and inside edge of the outside ski at edge change. This issue was introduced in THE MECHANICS OF BALANCE ON THE OUTSIDE SKI: TIMING OF EDGE CHANGE. The rocker impulse loading mechanism and the ability to balance on and control the outside ski is dependent on the ability to rapidly tension the biokinetic chain that stiffens the forefoot and torsionally stiffens the ankle and knee joints. This process enables top down, whole leg rotational force, into the turn, to be effectively applied to the foot and ski from the pelvis.

A Middle Ground on Stance

Although there is much discussion in skiing on the subject of stance, it is rare for discussions to include, let alone focus on, the foot.

The red rectangle in the graphic below shows the mid stance phase in the 8 component Gait Cycle.

A common position amongst the various authorities in skiing on stance, is that it is represented by the mid stance phase of the Gait Cycle. The 8 component Gait Cycle is the universal standard for discussion and analysis of gait in human movement. During the turn phase, the sole the outside foot or stance foot is in substantially constant contact with the zeppa or boot board. Since the ski stance does not involve initial heel contact or terminal phases, it was reasonable to conclude that skiing must be a mid stance activity.

Assuming that stance skiing is a mid stance activity also meant that the joints of the foot are mobile and the foot is still pronating and dissipating the shock of impact. The fact that the foot is not yet fully tensioned in mid stance, while still pronating, appears to have led to the conclusion that the foot is unstable and in need of support. Towards this end, form fitting footbeds, liners and, more recently, form-fitted shells were introduced and soon became standard. I described what has become known as the Holy Grail of skiing; a perfect fit of the boot with the foot and leg; one that completely immobilizes the joints of the foot in my post, A CINDERELLA STORY: THE ‘MYTH’ OF THE PERFECT FIT.  This objective, precipitated the premise that forces are best applied to the ski using the shaft of the ski boot as a handle with the leg acting as a lever. In this paradigm, the foot was relegated to a useless appendage.

The Missing Ninth Component – Late Stance

The problem with the assumption that mid stance is the defacto ski stance is that it has only recently been suggested that a critical ninth component, Late Stance, is missing from 8 components of the Gait Cycle.

Although it has been known for decades that the foot undergoes a sequential loading/tensioning process that transforms it from what has been described at initial contact as a loose sack of bones, into a rigid lever in terminal stance for propulsion, the effect of fascial tensioning on late stance has remained largely unexplored until recently when the exclusive focus on the rearfoot began to shift to the forefoot. I discuss this in BOOT-FITTING 101: THE ESSENTIALS – SHELL FIT.

As recently as 2004, Achilles/PA loading of the forefoot was poorly understood. Under Background, a 2004 study (2.) on the role of the plantar aponeurosis in transferring Achilles tendon loads to the forefoot states:

The plantar aponeurosis is known to be a major contributor to arch support, but its role in transferring Achilles tendon loads to the forefoot remains poorly understood.

The study found:

  • Plantar aponeurosis forces gradually increased during stance and peaked in late stance.
  • There was a good correlation between plantar aponeurosis tension and Achilles tendon force.
  • The plantar aponeurosis transmits large forces between the hindfoot and forefoot during the stance phase of gait.
  • The varying pattern of plantar aponeurosis force and its relationship to Achilles tendon force demonstrates the importance of analyzing the function of the plantar aponeurosis throughout the stance phase of the gait cycle rather than in a static standing position.

Changes in Muscle-tendon unit (MTU) and peak EMG increased significantly with increasing gait velocity for all muscles. This is the first in vivo evidence that the plantar intrinsic foot muscles function in parallel to the plantar aponeurosis, actively regulating the stiffness of the foot in response to the magnitude of forces encountered during locomotion. These muscles may therefore contribute to power absorption and generation at the foot, limit strain on the plantar aponeurosis and facilitate efficient foot to ground force transmission.

Transmits large forces and foot to ground force transmission means large downward forces directed at the ground or to a ski and from there to the snow.

Although I did not understand the esoteric details of fascial tensioning back in 1993, I was sufficiently aware of the relationship between peak tension in the plantar aponeurosis (PA), to be able to construct a simple model that illustrates how peak PA tension results in peak Achilles tension and how this causes the soleus muscle to go into isometric contraction, arresting further forward movement of the shank. I discuss this in detail in my series of posts on the SR Stance.

The photos below shows the simple model I made in 1993. Simple models of this nature are finding increasing use today to model what are called Anatomy Trains.

In late stance, the foot gets shorter in length and the arch gets higher and tighter as intrinsic tension transforms the foot from a mobile adapter in early stance into a rigid lever in late stance so it can apply the high force to the ground necessary for propulsion in the terminal stance phase that occurs at heel separation. The graphic below shows how the arch height h to foot length L ratio increases as the foot is getting shorter and the arch gets higher in late stance.

What has only recently being recognized is that the fascial tension that occurs in stance maximizes balance responses, neuromuscular efficiency and protection of the lower limbs through a process of  foot to core sequencing; one that stiffens the forefoot and torsionally stiffens the joints of the ankle and knee.

Loading/Fascial Tensioning Speed

A 2010 study (4.) found:

Early-stance tension in the PA increased with speed, whereas maximum tension during late stance did not seem to be significantly affected by walking speed. Although, on the one hand, these results give evidence for the existence of a pre-heel-strike, speed-dependent, arch-stiffening mechanism, on the other hand they suggest that augmentation of arch height in late stance is enhanced by higher forces exerted by the intrinsic muscles on the plantar aspect of the foot when walking at faster speeds.

…… or, by more rapid, forceful impulse loading at ski flat – see SUPER PETRA VLHOVA’S EXPLOSIVE IMPULSE LOADING IN ASPEN SLALOM

A 2013 study (3.) found:

Although often showing minimal activity in simple stance, the intrinsic foot muscles are more strongly recruited when additional loads are added to the participant.

A 2015 study (5.) found:

Changes in Muscle-tendon unit (MTU) and peak EMG increased significantly with increasing gait velocity for all muscles. This is the first in vivo evidence that the plantar intrinsic foot muscles function in parallel to the plantar aponeurosis, actively regulating the stiffness of the foot in response to the magnitude of forces encountered during locomotion.

These muscles may therefore contribute to power absorption and generation at the foot, limit strain on the plantar aponeurosis and facilitate efficient (vertical) foot to ground force transmission.

…….. or foot to ski to snow force transmission.

The Optimal Ski Stance is Unique

While the optimal stance for skiing has the greatest similarity to the late phase of stance, I am not aware of any stance that has requirements similar to the ski the stance where a specific loading sequence precedes rocker impulse loading as the outside ski changes edges in the top of a turn.

As with the gait cycle, the movement pattern associated with a turn cycle also involves loading and swing phases.

Time To Cascade

There are two intertwined rocker mechanisms that impulse load the forefoot at ski flat between edge change. These rocker mechanisms rely on what the 3 components of what I refer to as the Time To Cascade which is only possible when the plantar aponeurosis is rapidly fascially tensioned.

  1. Time to Fascial Tension which affects,
  2. Time to Stabilization which affects
  3. Time to Protection which protects the lower limbs 

In my next post, we will Meet the Rockers and continue with the discussion of the mechanics of balance on the outside ski.


  1. http://musculoskeletalkey.com/gait-and-gait-aids/
  2. Dynamic loading of the plantar aponeurosis in walking –Erdemir A1, Hamel AJFauth ARPiazza SJSharkey NA. J Bone Joint Surg Am. 2004 Mar;86-A(3):546-52.
  3. Dynamics of longitudinal arch support in relation to walking speed: contribution of the plantar aponeurosis – Paolo Caravaggi, Todd Pataky, Michael Gu¨ nther, Russell Savage and Robin Crompton – Human Anatomy and Cell Biology, School of Biomedical Sciences, University of Liverpool, Liverpool, UK – J. Anat. (2010) 217, pp254–261
  4. The foot core system: a new paradigm for understanding intrinsic foot muscle function – Patrick O McKeon1Jay Hertel2Dennis Bramble3Irene Davis4 Br J Sports Med doi:10.1136/bjsports-2013-092690
  5. Active regulation of longitudinal arch compression and recoil during walking and running Kelly LA, Lichtwark G, Cresswell AG – J R Soc Interface. 2015 Jan 6;12(102):20141076.

SUPER PETRA VLHOVA’S EXPLOSIVE IMPULSE LOADING IN ASPEN SLALOM

I am blown away by the explosive impulse loading of her outside ski that Petra Vlhova displayed in winning today’s World Cup Slalom in Aspen, Colorado. Vlhova’s powerful impulse loading made other racers, including Shiffrin, look like they were in slow motion in comparison. There are several videos of Vlhova in action on YouTube already.

For those who don’t know how to change video speed and definition in YouTube, the screen shot below shows the range of speed options available from 0.25 to 1.5 times Normal. To select the speed option, click on the gear that says HD then select Speed. I usually watch race videos in several speeds, including pulse frame stepping using the space bar on my keyboard.

Vlhova’s rapid and explosive loading of her outside forefoot at edge change literally supercharges the small nerves in her feet and the muscles in her foot to pelvic core in a way that transforms her into a literal super racer.

Petra; on it – all over it.

Here’s a short video clip in reduced speed of Super Petra in action. In one word; WOW!

Bravo Petra Vlhova! You made my day.