A central premise in skiing, especially in ski teaching and coaching, is that skiers and racers can learn to ski like the best by observing and copying them. Hence, articles and videos that talk in nebulous terms about good balance, an athletic stance, pressure control, steering, edging, extension, separation etc. as elements that, when blended together, will enable skiers and racers to ski like the Hirschers and Shiffrins of the world. If a racer who has undergone training in the system is not competitive or worse, suddenly becomes uncompetitive, the racer is typically blamed for not being strong enough or not pushing themselves hard enough or not taking enough risk or some other factor. In the end, the responsibility for lacklustre performance is conveniently assigned to the racer.
Ski boots are rarely considered a factor. So long as the boots are comfortable that is the only thing that matters. To suggest otherwise is to blame the equipment. This flies in the face of my experience. But until the skate study (1.) I had no reliable way of measuring and thus comparing performance.
The two pressure studies done in 1998 by the University of Ottawa with elite ski instructors provided an opportunity to compare the results of the studies to those of the 2012 skate study that I modified skates for. This study was also done by the University of Ottawa. Of the three studies:
- One 1998 skier pressure study used three highly skilled ski instructors (CSIA level IV)
- One 1998 skier pressure study used six internationally certified Canadian ski instructors.
- The 2012 skate study used five competitive skaters.
The 1998 study with the six internationally certified Canadian ski instructors provided Peak Force data that I could use to compare to the Peak Force data obtained from the 2012 skate study.
As I pointed out in my previous posts, skating and skiing are similar in that they both depend on the ability of the participant’s neuromotor system to create a foundation of dynamic stability across the skate blade or the inside edge of the outside ski prior to being able to effectively apply force to the ice blade or ski edge. The existence of dynamic stability across the skate blade or inside edge of the outside ski enables the neuromotor system to regulate fore-aft stability in what is typically referred to as skater or skier balance.
Peak Force is the highest force applied in an Impulse Force
In the skate study skaters performed forward skating sprint starts in each skate (OS and NS) for a total of 6 trials each. As would be expected with competitive skaters Dynamic Stability as represented by Peak Force was very close among the skaters in their Own Skates as shown in the graphic below.
But when the highest and lowest Peak Forces of the competitive skaters were compared to the highest and lowest Peak Force of the internationally certified Canadian ski instructors the difference was much greater; approximately 125% for the skaters and 300% for the ski instructors. The researchers noted this significant variance and suggested equipment could have been a factor. But that aspect was not investigated.
Peak Force Improvement
It would seem logical to assign sole responsibility for such marked differences to inferior muscle strength or improper training. Muscle strength and training are definitely important factors. But their contribution to overall performance is dependent on the ability of a competitor to create dynamic stability and quickly acquire a position from which they can effectively apply force to a skate blade or edges of a ski. These factors, in turn, are dependent on a functional environment in the footwear for the physiogic function of the lower limb.
As shown in the graphic below, when the same skaters switched from their Own Skates (OS) to the skates I prepared (NS) there was an immediate and statistically significant improvement in mean Peak Force of approximately 190%. Even more significant is the fact that the Peak Force of skater number 4 (the lowest of the four skaters) increased by approximately 252% changing the skater’s ranking from #4 to #1.
Impulse Force Improvement
An Impulse Force is a high force of short duration that causes a change in momentum.
When the skaters switched from their Own Skates (OS) to the New Skates (NS) there was an immediate mean increase in Impulse Force of approximately 216% as shown in the graphic below. Even more significant, the Impulse Force of skater number 4 (the lowest of the four skaters in their Own Skates) increased by approximately 276% raising skater number 4 to almost the same level as skater number 3. Meanwhile, an increase in Impulse Force of approximately 224% raised skater number 2 to almost the same level as skater number 1. In other words, the New Skate was literally a game changer that resulted in a leveler playing field for the four competitive skaters.
Center of Force (CoF) Variance: Where Races are Really Won
The most significant effect of the New Skate (NS) was on what is called Center of Force (CoF) Variance. Center of Force Variance is the amount of forward movement of the Center of Force within a fixed unit of time to the position on a skate blade or ski edge where force can effectively be applied.
The graphic below shows the Center of Force Variance of the four competitive skaters in their own skates (OS).
The graphic below shows the Center of Force Variance of the four competitive skaters in their Own Skates (OS) compared to the Center of Force Variance in the new skates (NS). When the skaters switched from their Own Skates (OS) to the New Skates (NS) there was an immediate mean increase in CoF Variance of approximately 172% as shown in the graphic below. Skater number 4 experienced the largest increase in CoF Variance (approximately 241%) that changed the ranking from #3 to #1.
An increase in the variance of CoF results in increased control during the stance phase of forward skating.
The graphic below shows what would happen if only skater number four were provided with New Skates (NS) while the other 3 competitive skaters continued to use their Own Skates (OS). Think of the red dashed line at 1.20 as the finish line of the CoF Variance race. It should obvious who will win and who will have the advantage at every turn.
The Score for Skater Four
Skater number four experienced the following improvements in the New Skates (NS) over their Own Skates (OS)
- Peak Force – 252%
- Impulse – 276%
- CoF Variance – 241%
- Mean improvement – 256%
The improvement in the three metrics was immediate and, based on my experience with skiers and racers, probably immediately reversible simply by having the competitive skaters revert to their Own Skate (OS) format.
Few forms of athletics place as high demands on the footwear used in their performance as alpine skiing. It (the ski boot) functions as a connecting link between the binding and the body and performs a series of difficult complex tasks. (2.)
To paraphrase Dr. Emily Splichal:
A skier is only as strong as they are dynamically stable.
In my next post, I will discuss the implications of the skate study and associated performance technology and metrics for the future of skiing, especially ski racing.
- A Novel Protocol for Assessing Skating Performance in Ice Hockey – Kendall M, Zanetti K, & Hoshizaki TB – School of Human Kinetics, University of Ottawa. Ottawa, Canada
- Ski-Specific Injuries and Overload Problems – Orthopedic Design of the Ski Boot – Dr. med. H.W. Bar, Orthopedics-Sportsmedicine, member of GOTS, Murnau, West Germany