Less Forward Lean = Higher Risk of Knee Injury?

it's more along the lines though of if you are a less "aggressive" skier, you can use a less athletic motion that matches the less forward lean and upright skiing.

 

If you are a more "aggressive" skier in a more athletic skiing, then the extra forward lean allows you to remain in that "aggressive" position.

 

Think of it more like bicycle riders. The casual family weekend department store bikers just sit upright and pedal away.  But any serious "biker" with their own road bike and the full getup has a completely different crouched biking position bent at the waist with their core tightened to support their weight.

 

So yea, basically you want to match the forward lean to the type of skiing you plan to be doing.  

If you are an upright skier with raceboots then it's a mismatch.  Same as if you're a racing skier with upright comfort boots.

 

Perhaps another analogy is just the way snowboarders setup their binding angles depending on the type of riding they will be doing.

 

I think the injury prevention is an unrelated side issue, as that is left primarily to your binding and DIN to pop off your skis when you are outside your envelope and bailing out.

I'm with you on this. No "gas pedal" position for me. I like having more forward lean built into the system.

Knees do not have much twisting strength at all with the unbent posture. And I believe more potenial for hyperextensions as well.

Just feel way more solid in an old school attack mode.

I've gone through several boots with varying degrees of forward lean in an attempt to find a setup that works for me.

 

I could ski in all the boots I've been in, but from looking at videos of myself, it was apparent that I was contouring my body to remain in balance -- that is, I was fighting the position that my boots put me in.  I have finally found happiness with the Lange RS130's, which (to my understanding) is one of the most upright boots out there.

 

My point is that if you're in a boot that forces you to "balance" via some awkward body positioning, then I'd think your chance of injury goes up as your available range of motion is limited.  If your boot allows you to balance in a nice, relaxed stance, then your chance of injury goes down.  Depending on your body's geometry, the ideal forward lean of your boots will change.  For some people, that ideal forward lean will be substantial.  For me, it's minimal.

 

 

I think the OP is really talking more about pure body mechanics here. Balance is one thing but if you are balanced in a less sound position, is that actually desirable?

Mudfoot,

 

If more forward lean = more fatigue, isn't a more fatigued person likely to injure themselves more easily.  On the other hand if a more upright stance

is more easily balanced (strength wise) wouldn't that in itself be safer?

 

Most ACL injuries occur with the leg flexed and the skier out of balance on the uphill ski.

 

mike

 

PS.  I don't think anyone can completely straighten the knee joint while in ski boots without getting way out over the front of their skis,

the idea is to have the upper leg (femur) oriented in a more perpendicular position over the ski center, using the skeleton to support the

G loads instead of the quads.

Edited by miketsc - 7/31/12 at 10:13am

 

 

You said it, Quote: "Generally, you injure your ACL by being in the back seat, "  Butt behind heels---often caused by knee being too far forward and skier sitting back.

 

Isn't this back seat position, "a bent knee position", it isn't a straight leg position.

 

mike

Someone with birdleg calves might ski ok with 18 degrees of forward lean,, on the other hand, if he had 15 in circumference calves in the top of the boot he
might be in agony.
Bigger calves equals more tibia net forward lean and the need to sit back more.

To answer your question

---

I doubt it would make a lot of difference since the leg is very seldom (read never) in a static position and any time while skiing.
I also stand by my comments about fatigue affecting safety, so I think you are better off in a more centered position, (femur nearly perpendicular to ski center).

Mike
Edited by miketsc - 7/31/12 at 5:23pm

To answer you question:

 

Conventional wisdom is almost all knee injuries occour when the knee is bent...as your knees bend gets over 90 degrees (ie hips below your knees) the chance of blowing your knees, goes way up.  Having said that, you can get in that positon with boots with little forward lean, and a lot...so I dont think it matters.  Certainly never ever heard of risk of injury with straight legs...just the opposite. 

 

If your knees feel unstable in the more upright boots, they probably are.  But I highly doubt its a function of the fore/aft balance point, it would be a function of your lateral alignment being out.  Fix that.  If common symptom of poor lateral alignment is your knees "wobble" in/out.

Edited by Skidude72 - 8/1/12 at 12:52am

I would agree that fatigue is overwhelmingly more important in causing injury than any difference in forward lean.  I took the rear spoilers out of my Rossi Radical Pros--a lot less fatigue skiing off piste and I'm happy to sacrifice groomer performance for that. Anything that makes skiing more comfortable has to be good (by which I mean comfortable skiing fast,skiing powder, skiing steep, skiing bumps, etc--not comfortable cruising blue groomers.) I think the OP is over thinking the issue. (Over thinking isn't so great for skiing either.)

Jasper Shiely at Vermont Safety Research found that most ACL sprains occurred when the skier was off-balance on his uphill ski, with the hips below the knees.  Most of the rest of the injuries occurred when the skier landed a jump off-balance to the back,with the legs straight.

The range of forward lean among boots can't be much more than 6 degrees.  That doesn't seem like enough to have any affect on those 2 injury mechanisms.

 

BK

^^^^  This brings up the issue of the straighter you are the more compressive force is transmitted to the spine/hips/knees.  It seems intuitive (and that's never wrong, right?) that there's a certain amount of optimal flex/forward weighting that will minimize the chance of compression injuries; it gets much more complicated with other injuries common to skiing, however.  I think we need to keep in mind the difference between boot flex and weight distribution - just because you have 18 degrees of forward lean doesn't necessarily guarantee that you will be in the best position to absorb compressive shock.  Something that doesn't get the attention that I think it deserves, perhaps because it's very difficult to analyze, is, instead of focusing almost entirely  on the position of the body when the injury occurs, instead go back and determine where was the body when things first started to go bad. Boot lean angle may aggravate injury conditions the final moment, but it may also contribute to setting up the skier for injury in the first place.  Fatigue and pain are obvious examples, but I think it's more complicated than that.

Bode Klammer,

 

You are right about the variance in forward lean being about 6 degrees (mens boots), the problem comes in when you put different sets of legs (calf diameter) into those boots.

A 5 year old Salomon Falcon has about 18 degrees if we combine this with a leg with 18 inches of circumference calves, the net tibia forward lean can be huge.  This poor 

guy would have to sit back all of the time---his quads would be in agony until (if ever) he got his legs into good enough shape to hack the load.

Skiing under these conditions is a night mare to say the least, but we see if all the time.

 

Mudfoot, started off by commenting about more upright boots being detrimental to safety. Although the twisting forces are different the mechanical disadvantages 

of skiing in a squat, out weigh any problems associated with an upright stance.   All of the instructors are always chorusing "Stand Tall".  They definitely have reasons

for all of this.  Center of mass, fore/aft balance problems are controlled by ---boot board angle---binding differential heel to toe(delta angle)---forward lean of the boot---and calf circumference,

(these two are related), ultimately we need to get the skiers tibia into the correct position to allow the him to stand with his torso centered over the boot sole center and the femur carrying the load into the knee joint.  This allows the skier to use the thigh and trunk muscles to control position verses having to carry all the G loads and control position.

 

In order to absorb you have to be extend---if the knee is too far forward, extension will overload the shovel of the ski, the skier will then sit back a little and load the tails.

mike

There is really nothing correct in your post. Rookie mistakes? These are WC racers and pro free skiers studied along with general public. It's often massive compression forces that cause the skier to get the hips like that, takes certain skill to generate those forces in the first place.

The answer to your first question is "no". The answer to your second question is "Yes"
.
You need to also consider the other half of the twist, the ski is twisting, but something above the knee must be resisting that twist to cause the knee pop (or alternatively the ski is held firm and the twist is coming from the upper body moving....this is common too). Lay down on the bed and try it. Straight leg, you will notice that you leg can absorb twist in the Tibet/fib and hip....it can tkae a lot of twist easily. Now bend your leg so hips are below the knee and try again. You will note here the hip is locked, so only the tib/fib can twist which is not a lot, the knee has to do the rest, and with the ligaments tight from the flex, they now just snap.


In regards to you Second question, balance is dynamic, the greater your range of motion the easier it is. Straighter boots allow you to acess the upper range of your motion. Think of it like a mountain bike, 12inches of travel vs. 18inches. Which is easier to balance on at speed? You want more travel, not less....same with skiing, but your legs are the suspension system, more is better.


As I wrote earlier, I suspect your lateral alignment is way out creating your stability issues.

You start out talking about a tall stance seeming wobbly.

 

Now we are all curious----what boots are you in----what size boot---what size street shoe----has your lateral alignment been set up correctly---circumference of calf at top of boot?

 

mike

Not that it really applies to this discussion, but I suffered a tibial plateau fracture while skiing last January due to hyperextension.  This was in a pair of Salomon Course boots that have a fair amount of forwar lean so if you put yourself in a crappy position (I was skiing backwards and pitched forward - not on purpose - and trying to avoid hitting a friend that had fallen in front of me), you can suffer a season endig injury due to hyperestension.  My recovery has been slower than hoped and I'm not sure I won't miss the first half of a second season...

Sticking to the OP, bc there are tons of great offshoots that all have merit on their own, I think the question is does forward lean cause injury?

My bias is that I believe we are giving the boot an excessive amount of credit. From my experience, the skier settles into a posture that works for them. Really the diffence from 15-19 degrees is only relevant when the boot is on the showroom shelf.

My stance is quite similar in tele, at, racers, flexons once I am out & turning. Even in a WC 160 plug that I gas pedaled my 10 mm (quite a dumb idea as I could do nothing w the tails...) I assumed my stance relative to the starting point. Even though I can't seem to ski my Fult Tilts / Flexons, w / o a big lean shim, it is only to get me to my 'normal' stance.

Don't forget, between boots & models, sole length, pivot points, stiffness & liners all vary quite a bit. Even in the same boot, if you change a liner or footbed you alter the starting geometry.

I'm more curious about your disclaimer?

More details please.

After having had my knees abused for many decades in many dangerous sports, fights, and other unmentionable activities, I tend to agree with the basic premiss.  Knees are more easily injured when straight than when bent.  However, I have also found that if they are bent past 90 degrees, they once again become more susceptible to injury.  No studies, no proof, just my own decades of anecdotal information.

 

PS - regarding fatigue.  I can recall that often at the end of a long day a pair of very stiff forward leaning boots was all that was holding me up ;)

A lot of forward lean does not necessarily ski great. Are you taking in to account ski's that are designed for a more centered stance?

Actually some studies have found that a good deal of time is spent in the 80-110 ranges for GS skiers.....

 

 

Or steeps...