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ACL's and the danger zone.

post #1 of 4
Thread Starter 
Just returned from the Eastern Championships at Okemo, Vt and I had unpleasant misfortune to witness 3 kids blow their ACL's.

There is a strong connection between technique, body position, ski shape and the potential for ACL damage so I thought I might open a discussion on it here and hopefully help readers reduce the risk.

I will offer my insights on the subject, and hopefully there will be others with knowledge on the subject beyond mine that can expand on what I have to say so we can do some good.

First, in my opinion the biggest catalyst for ACL injury is getting in the back seat. With the knees deeply flexed and weight levered against the back of the boot the knees are in a very vulnerable position. Any torque applied to the joint in that position just magnifies the load that already exists because of the body position.

Also in this unstable balance position a sudden edge engagement can create such a sudden change of direction that the out of balance upper body does not get taken along with. The skis and lower legs change direction and take off, and the upper body maintains it's previous directional orientation. Guess where the torque created by the divergence is felt? Yep, the weak little knee. RIP!!

I watched this very thing occur 3 times last week and I knew from seeing it happen many times in past races that the knee was injured before the racer even hit the snow. Anytime someone gets levered against the back of the boot and tries to make an athletic recovery, or the edges over engage, the skier is in instant danger of injury. Why Bodie hasn't blown his yet with all his balance acrobatics is miraculous, but mark my words, one of these days he's going to do it.

The new shape skis are having a very negative affect on ACL safety. The problem comes from the extra rotational forces they place on the knee when the situation I've described above occurs. The extra side cut produces a much greater direction change, intensifying the torque on the knee. They are also more apt to inadvertently engage (called "hooking up") when the skier gets tossed into the back seat. When that happens the knee is placed in grave danger.

In the speed events last week (downhill and super G) the race officials were threatening to pull racers who had skis with a sidecut radius smaller than FIS requirements out of the competition if they didn't change skis. This was specifically because of the extra danger of hookup those small radius skis present at high speeds.

Also, there seems to be a greater tendency for women, especially younger women, to suffer ACL injury. The ratio I witness of girls injured to boys injured is very tilted to the girls side.

So what do we do to reduce our susceptibility to ACL damage. First, develop a sensitivity for fore/aft balance. Learn to feel where weight is centered on the base of the foot, and if the front or back of the boot is being pressured. You can't get yourself out of the back seat if you don't have a constant awareness or where your fore/aft center of pressure is.

Once aware maintain good middle of the foot balance. A bit of shin pressure on the front of the boot at the top of the turn is OK, as is a VERY slight contact on the rear boot cuff at the exit of the turn, but they (front or especially rear) should never be strongly levered against.

And when you find yourself suddenly and unintentionally in the back seat, and feeling out of control rule one is don't panic. Try to keep the skis as flat as possible until you can use your abs to pull yourself back forward back into a safe balance position, then gradually regain control of direction of travel. Using the sidecut for recovery is a dangerous tactic.

OK guys, take it away and add what you can. I think this is an important topic, it makes me sick when I see someone taken down on a sled because of something that with a bit of knowledge may have been preventable. I hope there are those out there who can expand beyond what I have started the thread with.
post #2 of 4
If you cannot get you're center of mass over the sweet spot for whatever reason then you will need to drop the hips back and laterally to the inside in order to roll edge to edge without twisting the skis. This sets you up perfectly for an ACL tear.

Most of the kids that I see racing cannot get forward due to their gear and bend and the knees, drop the hip laterally to the inside and roll the feet with their hands out in front of them. In past years the skis would not carve with this method and kids would have to learn to bring the inside hip forward into the turn to carve.
post #3 of 4
I remembered this article from SKI ( SKI ACL Advise ) stating that ski injuries have decreased over 50% in the last 25 years. But I didn't remeber that ACL injuries are actually up especially for Women. So kuddos to FastMan for trying to educate people (or at least keep them thinking) on this topic. This article from SKI also offers advise on avoiding ACL injuries.

Good knee health to all!
post #4 of 4
We had some detailed discussions about this a few years ago:
ACL Summary

More ACL INFO

Deceleration Training

BTW, I have many of the "susceptibilities." But a good off season training plan has kept me injury free!
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