There appears to be a widely held perception within the ski industry, even among coaches and trainers at the World Cup level, that skiing like Hirscher and Shiffrin is simply a matter of observing and then copying their movements. There also appears to be a widely held perception that strength training and training on BOSU balls, wobble boards, slack lines and thick foam pads will transfer to improved balance on skis.
In a recent article, Nailing the Coffin Shut on Instability Training Ideas (1.), trainer, Bob Alejo, cites 59 papers on the topic of instability training in support of his position that not only are the assumptions about instability training improving balance in a specific activity incorrect, instability training may actually have a negative effect on performance.
As far back as 1980, I had found that an immediate improvement in skier performance after ski boot modifications was a reliable indicator that the modifications were positive. Sometimes this was evident in the first few turns. I had also found that equipment modifications or equipment changes that had a negative effect did not become obvious right away. I didn’t understand the reason for the immediate and sometimes dramatic improvement in skier performance following ski boot modifications. But I suspected it had something to do with improved skier balance.
By 1990, I had hypothesized that elite skiers are able to create a dynamically stable foundation under their outside ski and foot in a turn to balance on by rotating the edged ski against resistance from the sidecut and that this has the effect of extending ground reaction force from the snow out under the body of the ski. But even after the Birdcage studies of 1991 validated my theory, I still didn’t fully understand the reason for the dramatic improvement in skier performance in the Birdcage tests or following modifications made to conventional ski boots. Strain gauges fit to the Birdcage showed forces and the sequence of loading. But the strain gauges could not measure the magnitude of the forces.
It was Dr Emily Splichal’s (2.) that answered my question when she said;
It doesn’t matter how physically strong you are. Without a foundation of stability, you are weak. With a foundation of stability, you are stronger and faster than anyone.
In his article, Nailing the Coffin Shut on Instability Training Ideas (1.), Alejo supports Dr. Splichal’s position:
The predominant theme of the training data analysis under unstable conditions is the striking reduction in force and, subsequently, power. It would be of no surprise then that the speed of motion, as well as the range of motion, were negatively affected under unstable conditions, as cited in the literature.
Reduced Force Outputs Result in Less Power
Essentially, even though both groups improved in some instances, the stable surfaces group outperformed the unstable group in all categories. So much so that it led the authors to conclude that the results of their study affirmed—what was a criticism then and now is fact—that unstable training does not allow for enough loading to create strength and data.
Simply put, athletes can handle heavier weight under stable conditions versus unstable conditions.
Dynamic Stability is critical for a skier or skater to assume a strong position from which to generate force while maintaining control and initiate precise movement from. A key marker of dynamic stability in ice skating and skiing is the magnitude of impulse force, especially peak force.
Impulse is a large force applied for a short duration of time. Peak force is the highest force applied during an impulse force.
If superior dynamic stability is the reason for the dominance of racers like Hirscher and Shiffrin then pressure data obtained during skiing should show higher impulse and peak forces than generated their competition. While the technology to measure these forces is readily available I don’t have access to this data even if it does exist. So I’ll use data generated from hockey skate study I was involved in 2012 that compared data captured from competitive skaters performing in their own skates to skates I had modified using principles from my patents and modifications described in this blog.
The first step was to capture baseline data from the test subjects own ice skates (OS). The bar graph below shows the peak force in Newtons applied by each of the four test subjects. Peak force has a very short duration.
Subjects 1 and 3 applied a peak force of approximately 800 Newtons. A pound is 4.45 Newtons. So 800 Newtons is approximately 180 lbs.
Test subjects #1 and #3 are almost identical. But test subject #1 has a very slim edge over test subject #3.
Test subject #2 is 3rd in ranking while test subject #4 is last.
Assuming this was a study of competitive skier test subject #1 appears to have a stability advantage over the other skiers. This would translate into quicker more precise turns (hairpin turns) and less time on their edges.
In my next post I will show what happened when the same test subjects used the skates I prepared.
- Nailing the Coffin Shut on Instability Training Ideas – https://simplifaster.com/articles/instability-training/