Science is confirming what we’ve known for years

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Science is confirming what we’ve known for years

Postby tigernbr » Wed Sep 04, 2019 4:24 am

Wide skis are bad for your knees and your skiing. Jackson Hogen’s latest article:

https://realskiers.com/revelations/why- ... our-knees/
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Re: Science is confirming what we’ve known for years

Postby blackthorn » Wed Sep 04, 2019 12:32 pm

Yes, I got this in my email yesterday. JH's writing style annoys me somewhat at times, but I thought this a was good one. It added to what most PMTS skiers will have recognised for years together with more specific detail on effects of rotation at the knee joint. I thought it was a very useful addition and deserves to be read by those interested in these things.
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Re: Science is confirming what we’ve known for years

Postby Darren » Tue Sep 10, 2019 12:11 pm

If the ski tip & or tail is wider then your tibia head is that hard on your knees ? Or is it just waist width wider then the tibia harder on the knees ?
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Re: Science is confirming what we’ve known for years

Postby ErikCO » Tue Sep 10, 2019 5:46 pm

Primarily the waist. I'm sure the tip/tail have some effect but it is what is underfoot that is the most important for your knees. I know that, anecdotally, I can ski up to ~80mm under foot without noticing any significant knee strain. At 85mm, my knees are noticeable more sore at the end of a day of skiing. At 90mm, the snow had better be really soft or else I will be hating myself after an hour or two. (And that is without even talking about what it feels like to do good tipping movements on skis that wide!) I can't imagine what it would be like to try skiing 100mm or 110mm on resort snow!
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Re: Science is confirming what we’ve known for years

Postby Ken » Fri Oct 04, 2019 2:59 pm

Hogen mainly missed the point. I've found no info about ski width relating to bone size.

Here is the original Slovenian scientific paper:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4541126/

Conclusion: The changed biomechanical conditions that occurred in the transition to a different ski width caused a change in the knee joint kinematics, and it appears that two different motion strategies were formed depending on the ski width. The strategy using narrow skis was a more pronounced knee abduction, while using medium and wider skis caused progressively increased knee external rotation (less internal). Both of these strategies most probably occurred due to the changed point of application of the ground reaction force. Furthermore, based on the results of the current study, it can be plausibly argued that the use of wider skis or, in particular, skis with a large waist width, on a hard or frozen surface as was the case in this study, could force the knee joint closer to the end of range of motion in transversal and frontal planes. In addition, using wider skis on a hard frozen snow may increase the potential risk of degenerative knee injuries; however the latter needs further justification. Such hard snow conditions are characteristic for most prepared ski slopes, especially in recent times when natural snow is lacking and has to be substituted with considerably more compact artificial snow. Finally, the overall results of the abduction and internal rotation in respect to turn radii and ground reaction forces indicated that the knee joint movements are likely one of the key points in alpine skiing technique.

Here is the Montana State University video with research based on the Slovenian data:
https://www.youtube.com/watch?v=ynVcTIHPkUo
Two of the take-aways here are that wide skis changed skier's style and PSIA L2 & L3 candidates had poorer scores on wide skis.

Bottom line: Narrow skis are always better unless flotation is needed in deep snow (probably >6").
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