3D Joint Movements

[karlo]

Tom Gellie's "3D joint motions of skiing (The feet, knees and hips)"


I love the closing statements.

"Analyze yourself"
What is foreign, this is "where you will find your next breakthrough"

 

[Josh Matta]

I liked that last video but rotational separation is not coming from our knees.....

 

[markojp]

I liked that last video but rotational separation is not coming from our knees.....

... alone.

 

[Doby Man]

The trick to getting actual rotation from the knee joint specifically is that you need to be fully flexed to exploit its full rotational capacity. There is almost none with a straight leg where rotation is produced by only the ankle and femur/hip socket. See how you can produce it sitting in a chair, knees 90 degrees with feet dangling, and without rotating your femurs see how far you can rotate your feet side to side. You will see the tibia and fibula achieve displacement from each other as they rotate under the knee joint. This is the rotational mobility we need to "bring the skis around from the knee down" in a fully flexed position. It is one of those skills that we can really only learn when we are skiing as skilled and as fast enough to work, learn and develop from a low CoM position (flexed knee). Something I casually refer to as "speed s/kills" and just another example the benefits from skiing fast that are otherwise unobtainable.

 

[Josh Matta]

when your fully flexed that is just the hip sockets turning.

Trust me a hinge joint can not become a ball and socket joint.


yeah and you can learn to do retractions turns going 2 mph......

 

[Rod9301]

True

 

[karlo]

when your fully flexed that is just the hip sockets turning.

What @Doby Man says is true. Bend the knee, and one can rotate it. Come to think of it, I think I may be doing that when I ski steeps, rotating at the knee

 

[Josh Matta]

ummm no....

Knee is a hinge joint.

When the knee is bent its just the femur rotating which is rotating the joint, but the knee itself can not rotate...but if you guys keep saying it because a video said it still will not change these facts. Sitting down right now, with me knees bent if I move my lower leg side to side that is my femur moving. I can put my hand on my upper leg and feel that.

 

[karlo]

the knee itself can not rotate

Lift fore-foot of one foot up, leaving heel down. While standing, rotate the foot with the heel as the pivot point. Here, you after right, the knee does not rotate. The femur rotates, the knee does not. You cannot do the rotation without femur rotation.

Now, do the same thing with your knees bent, say 100-degree bend. You can now rotate the foot without any movement of the femur. I'm pretty sure that's the knee rotating, not the ankle.

Now do the same things with fingers of your two hands on either side of the knee, the lower bony part (is that upper tibia?). You can feel rotational movement when knees are bent, but not when straight.

 

[Rod9301]

Lift fore-foot of one foot up, leaving heel down. While standing, rotate the foot with the heel as the pivot point. Here, you after right, the knee does not rotate. The femur rotates, the knee does not. You cannot do the rotation without femur rotation.

Now, do the same thing with your knees bent, say 100-degree bend. You can now rotate the foot without any movement of the femur. I'm pretty sure that's the knee rotating, not the ankle.

Now do the same things with fingers of your two hands on either side of the knee, the lower bony part (is that upper tibia?). You can feel rotational movement when knees are bent, but not when straight.

There's no way you can rotate the knee, that's not the way the joint is constructed.

Whatever you're feeling is the femur in the hip joint. You can actually search the web for your anatomy lesson, not hard.

 

[karlo]

no way you can rotate the knee,

in the exercise I describe, I am 100% positive I am not rotating my femur, both by looking at it and feeling it.

In a slight refinement of the exercise, I keep the foot in contact with the floor, but the foot rotation is still a pivot at the heel, to eliminate a degree of motion that may come from the ankle. I am now positive I am rotating at the knee.

Can someone decipher the technical speak in this?

https://www.ncbi.nlm.nih.gov/m/pubmed/6869656/

 

[karlo]

Can someone decipher the technical speak in this?

https://www.ncbi.nlm.nih.gov/m/pubmed/6869656/

Nevermind. I think the layman's version is here

http://teachmeanatomy.info/lower-limb/joints/the-knee-joint/

"NB: Lateral and medial rotation can only occur when the knee is flexed (if the knee is not flexed, the medial/lateral rotation occurs at the hip joint)."

 

[Rod9301]

Nevermind. I think the layman's version is here

http://teachmeanatomy.info/lower-limb/joints/the-knee-joint/

"NB: Lateral and medial rotation can only occur when the knee is flexed (if the knee is not flexed, the medial/lateral rotation occurs at the hip joint)."

Sorry, I don't think you understand this. But go on.

Do you think there is knee angulation as well?

 

[karlo]

Do you think there is knee angulation as well?

I tried that. No. I can't angulate at all.

I found this,

http://boneandspine.com/knee-range-of-motion/

"Normal range of motion of knee is
Flexion – 120-150 degrees
Internal rotation with knee flexed – 10 degrees
External rotation with knee flexed – 30-40 degrees"

and

"Rotatory Movements at the knee are of a small range. Rotations take place around a vertical axis, and are permitted in the lower compartment of the joint, below the menisci."

That is consistent with what I am feeling at what I was guessing to be upper tibia.

I'm pretty sure i am using knee rotation in steeps when I use a flexed position. With it, I think I get very early edge as I reach back behind me to grab the edge. When I am more extended, again in steeps, my turns are more (conventional?), with turn initiation occurring more outside, but still up, than behind me. All that said with a vague memory because I've never thought about it this way. I will next time I'm on steeps.

 

[Rod9301]

I tried that. No. I can't angulate at all.

I found this,

http://boneandspine.com/knee-range-of-motion/

"Normal range of motion of knee is
Flexion – 120-150 degrees
Internal rotation with knee flexed – 10 degrees
External rotation with knee flexed – 30-40 degrees"

and

"Rotatory Movements at the knee are of a small range. Rotations take place around a vertical axis, and are permitted in the lower compartment of the joint, below the menisci."

That is consistent with what I am feeling at what I was guessing to be upper tibia.

I'm pretty sure i am using knee rotation in steeps when I use a flexed position. With it, I think I get very early edge as I reach back behind me to grab the edge. When I am more extended, again in steeps, my turns are more (conventional?), with turn initiation occurring more outside, but still up, than behind me. All that said with a vague memory because I've never thought about it this way. I will next time I'm on steeps.

The internal and external rotation come from the hip joint.

Sure the tibia rotates a bit in the knee. Any joint will if you force it. But what muscles are you using to rotate it?

 

[Doby Man]

Now, do the same thing with your knees bent, say 100-degree bend. You can now rotate the foot without any movement of the femur. I'm pretty sure that's the knee rotating, not the ankle.

Karlo, when the knee is at 90 degrees and we isolate from the knee down by not turning our femurs, I still think that most of the remaining rotation comes from the ankle joints. But when you sit and twist your foot, if you put your hands on the tibia and fibula right under the knee, you will feel them rotate. Regardless of this easy to discover self assessment, I think that between Gellie's knowledge of skeletal anatomy and alpine technique, we can probably just relax and take it from him. I think the takeaway here is that we get different amounts of rotation in different places as the body changes from unflexed to flexed. Because the skeleton loses capacity for rotation in some areas as we flex low, we gain it in others areas that we need to exploit whenever and wherever possible such as directly below the knee.

 

[Kneale Brownson]

I think what one feels moving just below the knee when you rotate the foot with the knee bent is MUSCULAR movement, not the parts of the knee joint rotating.

 

[JESinstr]

Not to change the focus.... When working with beginners on fore and aft balance I am seeing that much of the time the real "culprit" keeping them from staying balanced in the "Ready" position is the lack of tilting the pelvis forward at the hip sockets supported by a strong core. Once they understand and make this happen, fore and aft balance stabilizes dramatically.

 

[Erik Timmerman]

Not to change the focus.... When working with beginners on fore and aft balance I am seeing that much of the time the real "culprit" keeping them from staying balanced in the "Ready" position is the lack of tilting the pelvis forward at the hip sockets supported by a strong core. Once they understand and make this happen, fore and aft balance stabilizes dramatically.

Some of that may be learning to recruit the hamstring too. Being able to tip forward without sticking your butt out.

 

[karlo]

Once they understand and make this happen

Can you illustrate this and share with me how you get them to understand and make it happen? Are there drills and cues?