FootFoundation Science
Brought to you by Eric Ward of Foot Foundation

Study of the inverse relationship between PSIA certification level and neutral pronation measurements.

The results are in, and r = .488

This result, is the correlation between how much people pronate, and the PSIA certification levels they have achieved. So much noise is made, about how important boot fitting, foot beds, alignment is to the skiing experience. Well, finally we have a number that expresses just how important it is, at least, where PSIA certification is concerned. If its so important to instructor certification program, imagine how important it could be for everyone else out there.

A test was conducted measuring the degrees of pronation and comparing it to PSIA certification levels.  Among 81 returning ski instructors in Aspen Co. The result was, r= -.488. Exactly what does that mean? To make this number mean anything, you simply square it. Which is 23. Which means 23% of the variance in certification success, is accounted for, by the degree of pronation someone has. 

(Thank you Darwyn Linder for the statistical, adult supervision).

So lets take this number and kick it around a little and explore what all this could mean. If you pronate, and there is a great chance that you do. If you do nothing at all to your equipment, there is a 23% opportunity for failure if you attempt level II or III, and you are completely ready in every other way. If you were lucky enough to be born with great feet, then 23% of the game is won, simply by showing up. It’s also interesting that there was also whats known as an inverse relationship meaning that the less you pronate, the better your chances of making it to the highest levels of ski teaching certification. This inverse correlation is quite telling as its an exponential problem. 

The test included 81 pros, admittedly this is not an enormous sample  group however, the number is considered a strong correlation. pros, the group included national demo team members, examiners, trainers, world cup athletes, right down to first year pros. 

This is more than just a little interesting, that almost without exception, the best feet out there, end up making it to the national demo team, and the world cup, examiners, and definitely Full cert.  If you are not in the lucky foot club, well you could try to do more training, or maybe you need to spend some serious time thinking about how to get your feet and your skis communicating better. Problem is most boot gurus don't look at feet position in the formula currently.  "Arch support" and dynamic foot positioning are not the same thing. 

Outside of this test I have been measuring in the same way members of the PSIA national team for many years.  In this mini experiment, I can say that out of 25 members of the team I have measured.  All but one have at least one if not both feet in the lucky 1.5 degree target zone or less. Thats 99% that measure in the exact same place.  Why is 1.5 the best place to be?  Well one other thing I do is measure the lateral  internal angle of boot boards, or zeppas.  In this data gathering effort I can say with absolute certainty, that most boots have about exactly 1.5 degrees in them from the factory.

Interestingly, when measuring alpine ski racers, most that make it to the U-18 and above successfully, also fell into the lucky 1.5 or less in club. Obviously the kids with a lot of pronation got filtered out early on in their careers. So as far as predictors of who will, and who won’t make the cut? In skiing, predictability, could simply boil down to measuring how much you pronate.

How might this issue impact the experiences of average skiers? You ask a Great question. If you widen your view from just ski instructors, and look at anyone trying to learn to ski. Here is how the bell curve probably tolls for them.  The distribution of pronation among the general population is skued significantly toward the heavily pronated side. Its scary to imagine, that even today, in our incredibly advanced world, only 10% of humans land in 0 - 2.5 degrees of pronation group. This is the "functional" zone. 55% of humans pronate between 2.5-4.5 degrees. This is the "moderately" pronated group. Then there is the unlucky, but lovable group of walking wounded out there, who are perpetually on the mend. they suffer through their lives pronating somewhere between 4.5 - 6 degrees or more, the "excessive" group. Destroying their body every time their feet hit the ground. These are the groups of people I feel we can save.

Amazingly, 65% of ski instructors, come from this the lucky 10% group. Proving that there is a natural selection process in effect when it comes to just being a ski pro in the first place. 

One problem with this whole thing, is that most of the ski industries decision makers out there are successful ski teachers and some times ex ski racers, that went on to run this business. So when someone comes up to them with another foot saving system. From their perspective its very difficult to imagine the size of the battle someone may be fighting inside their boots, when the battle in their boots is largely non existent. So now we can hopefully put this conversation in perspective for everyone. The best feet out there have a 23% natural advantage over other less lucky folks.

I know this is all boring number crunching but If you can bear with me a bit longer, I want to try to paint an even clearer picture for you, highlighting just how important feet are, with respect to learning to ski, and why we may be loosing the battle for beginners so badly. We now know that roughly 80% or people that try skiing for the first time, quit  after their first experience. And we also know that 90% or people simply can’t stand up and balance dynamically on one foot, functionally. Which coincidentally is the most basic requirements of the sport. The 10%ers can fall asleep on one foot. BOOM, there it is, this is why so many people quit. If 23% of getting to the highest levels in ski teaching is attributed to how much you pronate, why would it not be just as important for learning to ski from the very first day? Skiing is simply a foot thing, we attach skis to them, they hold us up while in motion and they are the key to feeling our way down the hill. If they are cold and prickly they can’t help much. If they are warm and fuzzy, they have a much better chance of learning.

I believe that this test result also suggest that, when looking at the problems we face with beginners, we have to consider the possibility that at least 23% of it boils down to basic foot issues. It could easily 1/5th of skiing. The more you pronate the more important the problem becomes for you. Look at this from another perspective, the naturally gifted skiers are born with 1/5th of skiing figured out for them. Boots are made for perfect feet exactly like theirs. They never have to even think about it what their feet do inside the boot. These are the people we love to hate. they even say out loud, I could pull any boot, from any box, and ski it exactly the same, with no problems. Really??? Thats because they are in the lucky 10% group. For the rest, the 90% of the world, further away from 1.5 degrees you are in life, the harder you will have to fight to have the same amount of fun. The natural athlete that always remains relaxed in every situation, is the ultimate goal for any wannabe athlete. It’s something that you literally can not teach. You are either born this way, or not. The one bit of good news is, now we can measure exactly how far away you are to being that naturally gifted skier. And on your first day, you can have the feet of a gold medal skier on the first day.

Many people have shared stories about attempting certification levels, failing, and then been told it was their alignment. Immediately after visiting the best boot guru they know. Well why you ask? It turns out pronation is a bit of a ghost in conversation. People seem to think that with “arch support” all evil will be wiped away. Well it turns out, thats simply not working. If you are someone that already has good feet, and the boot gurus makes a foot bed, since you are almost perfect to start with. Any small change makes a world of difference. If you are moderately pronated and you go to the same person you my find slight to modorate improvement, but certain symptoms may persists, and things may just not feel perfect to you. If you happen to be extremely pronated you may feel you just wasted your time and money, and Trainers and examiners will continue to say “you should go see someone about those boots, again… Great evidence that the problem was made less bad but its still there. Thats because foot beds and canting don’t always fix all the problems.

Analyses of SBS data from Excel – 2015 Work Ready Data – 4/20/2016 report

Correlations: giving a value between +1 and −1 inclusive, where 1 is total positive correlation, 0 is no correlation, and −1 is total negative correlation.

(whole sample) Left/Right pronation – r = .803; (Ski & SB only) r = .764 (this means that both feet have similar degrees of pronation, so total pronation, L+R, can be used for some analyses)

(whole sample) Sex/Right pronation - r = .017; Sex/Left pronation – r = .048; Sex/Total pronation - r = .034

(this means that gender is unrelated to degree of pronation and male and female data can be combined)

(whole sample) Seasons/Total pronation – r = -.298; (Ski & SB only) r = -.316

(this means that the more pronation a person has the fewer the number of seasons they complete)

(whole sample) Age/Total Pronation - r = -.257; (Ski & SB only) r = -.164 (weak predictor)

(this means that over the whole sample there is a lower degree of pronation as age increases, suggesting that people with higher degrees of pronation drop out earlier than people with lower degrees of pronation)

(Ski & SB only) Certification Level/Total Pronation r = .488

(this means that people with lower degrees of pronation achieve higher levels of certification)


(Ski & SB only) degree of pronation for injured compared to non-injured

Mean total pronation for non-injured 2.3 degrees

Mean total pronation for injured 3.15 degrees

t.test p = 0.012

(this means that injury is significantly more likely for those with higher degrees of pronation; the p value indicates that this result would be found by chance only 12 times in 1000 tests)

(Ski & SB only) current age of injured compared to non-injured

Mean age for non-injured 44.317

Mean age for injured 52.

t.test p = 0.005

(this means that injury is significantly more likely for older Pros; the p value indicates that this result would be found by chance only 5 times in 1000 tests)

severity injury key

0= no injury

1=mild injury sprain, strains

2=modorate injury tears but non surgical fixes MCL,

3=severe surgical fixes ACL,

4=multiple severe multiple surguries Multiple ACL

The above chart shows some very interesting trends from 95 ski pros and proves the assumption that Injury rates are connected to how much you pronate. In the severity spectrum 0 means uninjured @ 60, and the average pronation among uninjured men and women are almost exactly the same. Of the injured 35 people, Level 1 were injuries like ankle sprains, or strains, vague pains. Level 2 was more significant recovery times and actually muscle or connective tissue tears that did not require surgery. Level 3 was surgical repair required, ACL, hip and knee replacement. Level 4 was anyone that required multiple surgeries.

Outlier focus

These are the two women form Level 1

Age sex years R L injury Injury cert dept

43 female 18 6 6 left ankle sprains 1 1 2 Sb School high risk

here is the data from one of the women snowboard pro, with 18 seasons multiple ankle sprains, cert 2, safer on a board with this much pronation. In a few more seasons we may see a more serious injury. Or she will quit.

55 female 30 1.5 5 ankle injury Left 1 1 2 Ski pro

Here we have someone who I predict will eventually blow up her left side somewhere. Already history of injury on side thats way more pronated. Also may see an injury on the good side from compensation efforts.

I am surprised we have not seen an injury yet could be a part time pro.

This is the subject from Level 2

30 female 14 5 3.5 right knee sprain 5 2 Ski pro Younger with fewer seasons no cert. Both sides are far enough out to see injury from either side. Skier so we will see this turn into an overuse injury.

Is there any correlation to the side that is more pronated and injuries on that side?

A quick, count shows 12 Pros injured a joint etc, on the more pronated side, 7 were injured on the less pronated side, 7 injured Pros had the same pronation on both sides, and 7 Pros had injuries on both sides. There is a trend in the direction of more injuries on the more pronated side, but we need a larger sample and a more detailed injury history so we can define the categories more precisely.

Pronation and certification