TRENDS IN WORLD CUP EQUIPMENT AND SKI TECHNIQUE


An interesting trend is emerging in World Cup Alpine competition. The movement pattern of some male racers is starting to resemble that of Ted Ligety while the movement pattern of some female racers is starting to resemble that of Mikaela Shiffrin. More interesting, Shiffrin has been struggling in the early races.  I’ll speculate later on why I think  Shiffrin is struggling.

In terms of the current trend in ski technique, it is not so much a case of Ligety and Shiffrin defining a new technique but more a case of them getting it right. By getting it right, I mean that they are skiing a technique that uses the innate, hard-wired processes of the human body, in particular, the basic movement pattern of alternating single-limb support made possible by the ability to develop a tensioned forefoot on the outside ski (DOT 4).

One aspect of this technique is the transfer of the load W to the proximate centre of the head of the first metatarsal where it acts in opposition to the point centre of Ground Reaction Force (COP) at the inside edge of the portion of the outside ski underfoot. The vector of the opposing force is perpendicular to the transverse aspect of the ski (DOT 7). This alignment of opposing forces is only possible when the proximate centre of the head of the first metatarsal is substantially aligned over the inside edge of the outside ski. The only way the centre of W can be aligned with the proximate centre of the head of the first metatarsal is through load transfer induced pronation at ski flat between edge change.

Due to the influence of Ligety and Shiffrin, World Cup ski technique is trending in a positive direction, as are skis. But the design of ski boots and modifications made to them continue to gather momentum in a direction that is antagonistic to load transfer-induced pronation.

“When the foot attempts to pronate inside the ski boot, it is often the case that the ankle bone will come to bear against the inner surface of the boot shell. When contact of this nature occurs, pain and other related complications usually result. Since the consensus of those skilled in the art of ski boot design and modification is that pronation or the rolling inward of the foot is detrimental, and, thus, undesirable, provision is not made to allow for such movement. Rather, the structure of the footwear is intended to resist or even prevent it.

“Thus, the problem with existing footwear arises due to the dynamic nature of the architecture of the foot. When the wearer is standing with the weight equally distributed between left and right feet so that the centre of mass of the wearer is manifesting itself in the centre between the feet, the architecture of the wearer’s foot assumes a specific configuration. As the wearer begins to shift his weight towards one foot so that the other foot bears proportionately less weight, the wearer’s centre of mass moves over the medial aspect of the weighted foot so as to assume a position of balance. In order for this movement of the wearer’s centre of mass to occur, the architecture of the weighted foot must undergo a progressive re-alignment. Existing footwear does not adequately anticipate this re-alignment of the architecture of the foot and thus such footwear inhibits the wearer’s ability to assume a balanced position.” – BACKGROUND OF THE INVENTION – US Patent No. 5,265.350 – MacPhail, November 30, 1993

A large camp in the ski industry appears to be of the position that the leg should ideally function as a lever with which to place and hold a ski on edge and apply forces to it. In this paradigm, the foot is viewed as a useless appendage, one that serves no purpose and only complicates the process of achieving a firm connection of the leg with the ski.

The relationship between equipment and technique is fragile at best. In the chicken and egg scenario, equipment enables sound technique. At the same time, equipment can disable sound technique once it has been established. The effect of equipment tends to become exacerbated in competition where races are won or lost by hundredths of a second. Here, seemingly minor changes can have major impacts on racer performance as reflected in results, which brings me to speculate on why Shiffrin is struggling.

It seems inconceivable that Shiffrin has lost her edge in competition. A more likely explanation is that she is literally not able to find her edge due to a change in some aspect of her equipment. Shiffrin comes across as intelligent, focused and disciplined. But like most racers today, she probably has minimal influence or control over her equipment, which is increasingly left to the experts. Indeed, the F.I.S. advises in their 2014-2015 rules document (http://www.artech-ski.com/fis/FIS-Alpine-Ski-Equipment-Rules-2014-2015.pdf), that, “Boot fitting for racers should be done by professionals, as there are many factors that play in to deciding on the correct fit.” I concur with the position of the F.I.S. that here are many factors at play in a ski boot. But the central issue is the affect of these factors on the physiologic function of the user. But this is an issue that does not seem to be appreciated within the ski industry in general, let alone by the F.I.S..

Instead, the prevailing mentality appears to be that solid technique can overcome equipment issues. This being the case, it is probable that her coaches, and even Shiffrin herself, may believe that correcting her current issues is a matter of making adjustments to her technique. But this is like saying that a skilled Formula One driver can win with an improperly tuned racecar. In order to maximize skier potential, the skier/ski equipment components need to be optimized as a system. They are not mutually exclusive. Yet, I have seen no evidence to date that this critical issue is even recognized. In ski racing, relative skier performance, not optimal skier performance, prevails. Here, luck appears to be the main factor in terms of skier/equipment synergy.

The following elements, which will be the subject of future posts, are characteristic of a sound ski technique.

  • A transition phase between at the end of a turn to initiate load transfer to the inside (new) ski.
  • Rotation of ski into the new turn initiated by load transfer to the inside leg while the ski is still on its inside edge.
  • Extension to create load transfer and move COM forward so as to align Resultant, Centre of Load W and Ground Reaction Forces.
  • One hundred percent of the load expressed on the new outside foot and ski at ski flat between edge-change.
  • Coordinated ankle, knee, hip flexion at ski flat to initiate load transfer induced pronation
  • External forces engaged at edge change to drive the torques into the turn and set up a cantilevered platform (DOT 4) of contiguous GRF to support the superincumbent body of the skier and provide reaction force for postural responses.
  • The use of the inside leg as a strut with which to brace the pelvis so it can be oriented to assist in the alignment of R emanating from COM through the proximate centre of the head of the first metatarsal.
  • Phased, multi-plane torques into the turn.
  • Whole leg internal rotation from the pelvis coordinated with edge change.
  • Achilles induced plantar aponeurosis tensioning (tension in the sole of the outside foot).

It is the synergy of these things that allows a skier to engage the process of innate flow balance (DOT 13) with its hyper-speed subconscious information bit processing rate.

“When I ski, it’s like a song. I can hear the rhythm in my head, and when I start to ski that rhythm and I start to really link my turns together, all of a sudden there’s so much flow and power that I just can’t help but feel amazing.”

—Mikaela Shiffrin

I believe that some factor in Shiffrin’s equipment is causing her to make conscious corrections on course. Unless this issue is accurately identified and corrected and soon, she will find it increasingly difficult to ski with innate flow balance.