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Ankle Motion, is it needed? - Page 3

post #61 of 131
Wow!

Guess I won't be measuring my boot board. It is cork and completly glued into the the boot. There is some ramp but it seems minimal.

A-man!
post #62 of 131
I'm talking about the angle of the foot relative to the bottom of the boot. Ramp angle is what I've always heard it called. I ski atomic bindings, they have no delta angle, they are flat.

I measured by taking the boot board out of the boot and laying it on my desk, laying a straight edge across it, and using a protractor measuring the angle. I have to say that it took a little work to get it to 3 degrees, I followed someones directions. I always found that my boot boards will come out of the boot. This has been true of technica's, atomics, and my heads. Don't know anything about solomons. This year I'm going to try to subtract a couple more degrees from my cuff. We'll see.

As I was modifying my boot board, I could watch my stance adjust in the mirror at home. Along the same lines as what Witherall suggests with the phone book rountine, except I had a goal of 3 degrees in mind over a flat surface. It was pointed out to me that many boot boards are not flat and this can have an impact also. All I know is that I could feel a difference and many could see this difference in my stance, but of course there is alway an unlearning process when changes of this nature are made. I'm still working on utilizing my more functional stance. ;>)) Later, RicB.
post #63 of 131
Speaking of stance, I came across this definition the other day:

Quote:
Stance is the way your body segments are aligned with each other in relation to the base of support at your feet, which is determined by the angles of your ankle, knee and hip joints. The ankle joint has the greatest effect on stance.
The author adds: "The reason for the latter statement is that the ski boot can have a significant effect the angle of the ankle joint typically putting it outside the range it was designed to operate in for efficient stance."
post #64 of 131
That's a good definition of stance Nolo. This brings up the question of what role we want our boots to perform. If my body is maintaining stance on it's own, I want my boots to facilitate and support good stance and not force or create stance in it's own image so to speak. Figure out what minimul range of motion my ankle needs to opperate in fore, aft, and lateraly, and then fence it in with a good boot to help keep it where it needs to be. Plant and grow your crop on the most fertile ground. Later, RicB.
post #65 of 131
David M had a very interesting description of the optimal forward lean of the boot, hence root of stance. I think it was in the "balance bits" thread - it included a test that could be made just by walking to determine the optimal forward lean: The angle at which the soleus muscle snaps into action during your normal walking stride was claimed to be the optimal boot forward lean.

Any thoughts on this? His posts stated that this was experimentally determined through monitoring of the pressures under the foot while actually skiing and varying the boot angle with an exo-skeleton sort of contraption.

How does that position relate to the ease of squatting while is a ski boot? Is there a connection?
post #66 of 131
Quote:
Originally Posted by RicB
I'm talking about the angle of the foot relative to the bottom of the boot. Ramp angle is what I've always heard it called. I ski atomic bindings, they have no delta angle, they are flat.

I measured by taking the boot board out of the boot and laying it on my desk, laying a straight edge across it, and using a protractor measuring the angle. I have to say that it took a little work to get it to 3 degrees, I followed someones directions. I always found that my boot boards will come out of the boot. This has been true of technica's, atomics, and my heads. Don't know anything about solomons. This year I'm going to try to subtract a couple more degrees from my cuff. We'll see.

As I was modifying my boot board, I could watch my stance adjust in the mirror at home. Along the same lines as what Witherall suggests with the phone book rountine, except I had a goal of 3 degrees in mind over a flat surface. It was pointed out to me that many boot boards are not flat and this can have an impact also. All I know is that I could feel a difference and many could see this difference in my stance, but of course there is alway an unlearning process when changes of this nature are made. I'm still working on utilizing my more functional stance. ;>)) Later, RicB.
What vintage Atomic binding are you on?
post #67 of 131
BigE--great recollection there about DavidM's description of optimal forward lean!

His point, as I recall, was based on the idea that the soleus (calf muscle, responsible for dorsiflexing the foot and thus very important in fore-aft balance) works most effectively, especially for balancing reflexes, when it is partially stretched. The "stretch reflex" is a muscle's reflexive contraction reaction to sudden stretching. If the soleus is totally relaxed, this important balancing reaction will not take place. It makes sense to me!

However, this is just one component of optimal forward lean. The other is the need for a natural, athletic stance that maximizes the range "vertical" motion, as shown in the "stickman" diagram I posted on page 1 of this thread. It seems likely that one or the other of these two components may have to be compromised for some people, to accommodate the other. And I suspect that some skiers lack sufficient flexibility in their ankles to allow the degree of flex required for DavidM's method--a handicap, to be sure!

Note that increased delta angle (tipping the boot forward by elevating the binding heel), and increased forward lean angle (tipping just the boot cuff forward, or shimming behind the calf), both affect the angle of the lower legs. But only forward lean adjustments affect the tension in the calf muscles (soleus) by increasing ankle flex. So it seems to me that the proper sequence for boot fitters would be to optimize forward lean--perhaps with DavidM's technique--and THEN adjust delta angle to optimize the skier's stance.

Any thoughts from the real boot gurus around here? Jeff Bergeron?

Best regards,
Bob Barnes
post #68 of 131
Bob, I think what David was saying was that the soleus goes into eccentric contraction and not concentric contraction, which is what the stretch reflex triggers. For the soleus to go into eccentric contraction the hips, or rather the illiac crest has to be forward of the ankle, and the soleus is then resisting the CoM tumbling forward. This is when the loading response is happening in the foot also as I understand it, which is in concert with the foot pronating. I was fortunate to have many conversations with David and am truly gratefull for the knowledge that he was willing to share.

Really the stretch reflex in the lower leg as we tend to think of it, is more about the gastroc and is more applicable to hop turns and such as I understand it, though I think all our muscles are capable of this reflex. It is a sudden, protective contraction that happens when the muscle is stretched rapidly or too far. We can utilize it for sudden power but not for balancing, except maybe in recovery. Plyometric exercise takes advantage of this reflex. At least that's my take. Later, RicB.
post #69 of 131
Quote:
Originally Posted by Atomicman
What vintage Atomic binding are you on?
Atomicman I've got bindings that range from 4-5 yrs old to last year. I've been told by a couple of sorces that they have no delta angle. DavidM was one of the sources.

BigE I think the idea for me in using a squat to test my boot, is that in keeping the knee even or behind the toe the range of ankle motion needed is similar to a skiing stance, along with range of motion of the leg and hips. If the knees are forced to go beyond the toes while squating the hips will go back farther when I'm skiing and thus won't be over my instep or ahead of my ankles. It's just something I have found works for me in determining how a boot affects my balance staticaly. It seems to be the same range of motion I need in skiing. The key for is keeping the knee behind the toes. Later, RicB.
post #70 of 131
Yes, I miss DavidM too. He may have been a little headstrong at times, but he certainly brought a great deal of biomechanical knowledge and the ability to expound upon it to the table!

A small point: I would argue that it is not the hips, or the ilac crest, or any particular part of the body, that must be forward of the ankles to cause the soleus to engage. It is the center of mass that must be forward of the ankles. The CM may often be in the approximate vicinity of the iliac crests, but not always, and not necessarily. In a racing tuck, for example, the skier's hips are are way behind, but the boots, ankles, and lower legs, as well as the CM, can be appropriately aligned.

In my illustration, skiers A3, B1, and C3 show skiers in balance (CM slightly ahead of ankles), with hips well behind ankles. These skiers may or may not have enough ankle flex to trigger the soleus reaction, although even B1 might have enough--if he or she has very tight achilles tendons.

Best regards,
Bob Barnes
post #71 of 131
You are right Bob, the illiac creast is just a rerference for the CoM of a normal upright stance, be it walking or skiing. It does get very technical. Of course David would argue that a long postural stance is essential to funtional balance while skiing, whether upright or inclined, which is along the lines of not leaveraging the boot excessively for skiing that you outlined in your previous post on flex, stiffness and forward lean if I understood you right. I think one thing to remember is the angle of the ankle does affect the engagement of the soleus and also the gastroc, along with the angle of the knee. I'm still sorting this out along with it's relevance. To staticaly stretch both the gastroc and the soleus one has to move the knee between straight (gastroc) and bent (soleus). Later, RicB.
post #72 of 131
Quote:
Originally Posted by RicB
Atomicman I've got bindings that range from 4-5 yrs old to last year. I've been told by a couple of sorces that they have no delta angle. DavidM was one of the sources.

Later, RicB.
You are correct, Atomic's bindings are flat, but year before last when they went to the newer plate with the aluminum top they added about 4mm of ramp angle into the plate. The older race charger like was on the 9.16, 9.12(not the huge silver carving plate) & 10.22 was flat, but when the G11 and SL11 came out they added the ramp angle. I couldn't remember when I first asked you if it was in the plate or the binding so I went & measured some of our skis. I still have a couple of pair of 10.22's laying around and a 9.12. It is the newer riser.
post #73 of 131
Hello to all. I just got back from a surf trip cahsing the hurricanes on the east coast. Time to think skiing. Just thought I would throw a couple of tidbits here to get the gray muscle"brain" working.

The boots job is to resist pressure that is built up between the body/ski/snow. How much or too little resistance is the issue and personally relative to the body and task at hand.

Just to throw an oyster into the ankle flexion beef stew think about this. I skied ,and I know others on this discussion have skied, alpine boots that have been modified to restrict, for no other choice of words, ankle flexion and allow for the flex to occur at the ball of the foot. Cuffs completely riveted and sole flexibly as a nord boot . Unbelievable, never felt a ski bend so much. Very tactically alive and , don't forget, absolutley wonderful to walk in.

Just remember everyone has an opinion and those opinions are usually based on successes and faillures that are more emotional and personal at times regardless of statistics and science.What's the answer? I don't know!
post #74 of 131
Gomolfoot, to what do you attribute the ski bending so much, the movement of the pressure on the ski forward on the ski as the foot bends at the ball of the foot? Was the heel locked down still, and if so how was the flex under the toe enabled?

I know that DavidM did exstensive testing of these issues with his computerized "birdcage" on the snow, for which he won a canadian award. From my understanding of his reseach of forward lean and balance issues, the range doesn't change much from person to person, though there are other personal issues that affect performance such as muscle imbalances and skeletal alignment. This is the only real qualifiable info I have ever been exsposed to. Later, RicB
post #75 of 131
What I don't get Atomicman is why the industry would mount the binding further back than optimal and then tip us forward to try to get us back over the ski.

None of my atomic skis are new enough to have the new plate, and I got a new pair of last years r11's over a warranty issue late last year, so I probably won't be buying any thing this year. I owe my shop for that one. The new skis look fun and I will probably demo a few so I can advise my students better (right!). Later, RicB.
post #76 of 131
Good question. I don't remeber if their is ramp Angle in last years R11. I'll go measure mine. Great ski, isn't it?

over & out!
CW
post #77 of 131
That would be an interesting boot to ski in, Gmolfoot!

Welcome back--your boot fitting expertise and your input to these discussions is always illuminating.

Best regards,
Bob Barnes
post #78 of 131
Quote:
Originally Posted by nolo
Speaking of stance, I came across this definition the other day:



The author adds: "The reason for the latter statement is that the ski boot can have a significant effect the angle of the ankle joint typically putting it outside the range it was designed to operate in for efficient stance."
As I found out last year, this phenomenon can get even more interesting when one's feet are shorter than "average" as compared to height of CM. In my case, I stand 6' tall, but wear size 8.5 street shoes (and my Tecnica XTs are sized down). As a result, just a little ramp angle gets my knee out over my toes and out of the support base of the foot (between the ball of the big toe and the heel). Ramp angle thus needs to be flatter for me than for other folks...
post #79 of 131
Quote:
Originally Posted by RicB
What I don't get Atomicman is why the industry would mount the binding further back than optimal and then tip us forward to try to get us back over the ski.
Certainly for racers (as someone else here has observed first) we often pull the inside foot back and make a forward move early in the turn to lever the front boot cuff to bend the front of the ski to increase the steering angle of the ski, for a turn that is both fast (not much skidding) and tight (stays closer to an optimal line in setting up for the next gate.) Olle Larsson's article describes it here:

http://www.franconiaskiclub.com/PDFs/slalom.pdf


I suppose the idea may be (A) better to put the balance point a little back, and feel you have to get forward, than have the balance point right or forward, and have skiers getting back; (B) it fits with modern ski racing's dynamic balance, with Bode Miller style feet get ahead then get pulled back when the turn hooks up; (C) better to put ramp angle at the ski than have the skier bend at the waist.

I have Atomics, where you can shift your bindings fore-and-aft. They don't feel right shifted forward.

SfDean
post #80 of 131
Quote:
Originally Posted by Bob Barnes/Colorado
Note that increased delta angle (tipping the boot forward by elevating the binding heel), and increased forward lean angle (tipping just the boot cuff forward, or shimming behind the calf), both affect the angle of the lower legs. But only forward lean adjustments affect the tension in the calf muscles (soleus) by increasing ankle flex. So it seems to me that the proper sequence for boot fitters would be to optimize forward lean--perhaps with DavidM's technique--and THEN adjust delta angle to optimize the skier's stance.

Any thoughts from the real boot gurus around here? Jeff Bergeron?
Jeff did work on both forward lean (pulled out the shim on the back of the cuff) and delta angle (put shims under the toe of my Markers) when he was fitting me. He also looked at my ability to flex my ankle forward and the resulting effects on my legs. Could be he was assessing these kinds of things, but I'd love to hear what he has to say about it.
post #81 of 131
Quote:
Originally Posted by RicB
Really the stretch reflex in the lower leg as we tend to think of it, is more about the gastroc and is more applicable to hop turns and such as I understand it, though I think all our muscles are capable of this reflex. It is a sudden, protective contraction that happens when the muscle is stretched rapidly or too far. We can utilize it for sudden power but not for balancing, except maybe in recovery. Plyometric exercise takes advantage of this reflex. At least that's my take. Later, RicB.
Yes all skeletal musles should have it - mine is almost not there as I cannot feel the tension in the muscle.....

It is there "just" (a quiver that is very hard to detect) I think maybe the pain receptors fire & get the "twitch" happening but that would be closer to the end of muscle travel
post #82 of 131
Sfdean, what little industry testng there has been has shown people's preferences are to ski their skis more forward than the factory position. I ski all my atomics forward except for on my twin tips, which are back.

I had forgotten about that short foot, long leg pendulm effect Steve.

So on the original question of ankle use in skiing, there seems to be the issue of ankle position in skiing. This has an effect on posture as well as on muscle recruitment and our dynamic balance. If the ankle is positioned in a way that requires the knees to move forward and the hips back to maintain posture, then the entire recruitment patter of given muscles can change from agonist to antagonist, and also changes how we effect dynamic balance because of the changed role of the muscles. Studies have shown that the two are interrelated and unseperable. Add to this the mechanical disadvantage and inefficiency in a lowered stance and it would seem to me that it is all important that we determine the optimal angles of the ankle and foot ramp angle.

One study spoke of the pendulum effect of the CoM not working for us in a lowered stance gait and the effect this had on not only dynamic balance but muscle response. According to this study the Com movement is critical to dynamic balance and integral to any movement that propels us forward. This compounded when the trunk is tipped forward, and the knees and hips are kept bent. Kinda like skiing.

The industry pays little attention to this and componds the problem by introducing increases such as delta angle ect. I'm always stumped by this. Later ,RicB.
post #83 of 131
Quote:
Originally Posted by RicB
Gomolfoot, to what do you attribute the ski bending so much, the movement of the pressure on the ski forward on the ski as the foot bends at the ball of the foot? Was the heel locked down still, and if so how was the flex under the toe enabled?

I know that DavidM did exstensive testing of these issues with his computerized "birdcage" on the snow, for which he won a canadian award. From my understanding of his reseach of forward lean and balance issues, the range doesn't change much from person to person, though there are other personal issues that affect performance such as muscle imbalances and skeletal alignment. This is the only real qualifiable info I have ever been exsposed to. Later, RicB
Yes the heel is locked down. These are traditional boots that have gone through " Junk Yard Wars" . Worked with skill saws , drills and all of the other goodies that remove plastic. I can only attribute the feel of the ski to the fact that there is minimal resistance from the boot sole longitudinally as the ski does its' thing through the arc of a turn.I was asked to not divulge inventor or the boot manufacturer that was testing this stuff. Too many phone calls from interested parties will distract from their day to day creative flow. I will say that someone on this forum and discussion thread was and probably is very active with the early stages of this theory.
post #84 of 131
I understand about keeping things to ones self, I have been asked the same from certain individuals, and totaly respect this. Sounds interestng Gmolfoot, but how does this affect balance when the foot's platform isn't rigid? Does this interfere with balance feedback in any way? Later, RicB.
post #85 of 131
Quote:
Originally Posted by RicB
I understand about keeping things to ones self, I have been asked the same from certain individuals, and totaly respect this. Sounds interestng Gmolfoot, but how does this affect balance when the foot's platform isn't rigid? Does this interfere with balance feedback in any way? Later, RicB.
The balance issue is not a problem. Probably enhanced . Forefoot is for balance and the hindfoot power. COM can still adjust as the boot doesn't fles at the supposed ankle/cuff hinge , but at the forefoot /bellows area. Go get a tele boot , put on a set of booster straps, a set of jet sticks and try stand up skiing . Let us all know what the sensations are.
post #86 of 131
Quote:
Originally Posted by gmolfoot
The balance issue is not a problem. Probably enhanced . Forefoot is for balance and the hindfoot power. COM can still adjust as the boot doesn't fles at the supposed ankle/cuff hinge , but at the forefoot /bellows area. Go get a tele boot , put on a set of booster straps, a set of jet sticks and try stand up skiing . Let us all know what the sensations are.
Not sure I understand this forefoot for balance, hindfoot for power. Doesn't the heel and the first and fifth balls have to work in unison for balance to be effective? I understand the concept that toes are stabilizers but I need some further explanation to understand what you are saying here. The CoM will always seek to adjust and compensate, but does this mean it is the most effective to achieve dynamic equilibrium? Later, RicB.
post #87 of 131

Roll Em Over Batoven

Quote:
Originally Posted by RicB View Post
To answer the question do we tip down low or at the knee? The answer would be we tip down low, or load the foot in pronation, to engage the edge, and we edge our ski by inclination, our knee really doesn't tip sideways, but it can be taken out of alignment between our ankle and hip, but this is a weak position.
JUST A QUICK NOTE. . . ABDUCTION AND ADDUCTION OF THE THIGHS AND LINEAR (INSIDE) HIP FLEXION ARE THE KEY ELEMENTS OF (GROSS) BODY MOVEMENT REQUIRED TO TIP 'EM. THANKS FOR READING. GOT ALOT MORE IF YOU WISH. JR NOLAN
post #88 of 131
Quote:
Originally Posted by ydnar View Post
I would like to make a point here. Having a fore or aft alignment bias and being able to compensate for it by something like having very flexable ankles is not the same as correcting the alignment to bring the skier into a neutral stance. Proper alignment allows you to use the avaliable movements of your body to ski rather than waste them in striving to achieve fore/aft balance when fore/aft alignment is off.

In relation to this thread you can look at it like this. We put our feet in boots that greatly restrict our ankle flexion yet this ankle flexion is critical to our being able to ski. Now, given the above why would I want to use up some or all of that limited flexion to achieve fore/aft balance when I can get the balance through proper alignment and leave the ankle flexion for skiing.

yd
Well said ydnar! To ski in a stiff boot certainly has benefits when it places you in the proper postion but, is more intolerant of poor alignment than a softer boot. Softer boots will tolerate more inaccuracy but, reward good skiing less than stiffer boots. As Ydnar said, when a boot is properly aligned ankle flexion can be used for tactical skiing rather than trying maintain or find a balanced position. When in a stiffer boot that is well aligned/balanced to the skier and that skier can manage their movements accurately the rewards are great!



I will say changing to a stiffer flexing boot for me created more challenge in moguls and caused/forced me to be more proactive in moving my feet under me in anticipation of the terrain, though on groomers they were magic from the get go.

Accuracy is rewarded, inaccuracy or complancancy is punished. There is no sitting on the fence.
post #89 of 131
Quote:
Originally Posted by boozer View Post
http://ourworld.cs.com/BBRNZ/Backpe...ation+small.gif

I really like this animation. Although I think it really serves as an example of why ankle flex is needed in skiing. If you flex and extend your knee, hip, and spine without much involvement of your ankle, you end up with your knees in your chest. The same position the skier in the animation is in at the top of the mogul. Not a very powerful or desirable position and I don’t think you would see many good mogul skiers get in that position.

In my opinion boots that are to stiff tend to encourage people to rely on the boot for balance. In general good skiers with stiff boots tend to lean forward against them. This inhibits a skier’s ability to absorb terrain because they are constantly getting pitched even farther forward.

Ideally a skier is skiing in a boot that they can flex. How stiff a boot you want depends on a couple of factors. The first is strength; a stronger heavier person is going to be able to flex a stiffer boot. Second is how fast you ski. Faster skiers generate more force, so generally the faster you ski the stiffer you would want your boot.

Oh and as far as advocating a stiff boot for children I think it depends. A child that is strong enough will benefit from the range of motion that a softer boot allows. For children who haven’t developed much leg strength yet, a stiffer boot will give them more support and will probably be easier to ski in.

I am not speaking for Bob when I say:

If I were to hop up in the air and land (sans boots) into a deeply flexed position I would use up my whole range of flexion in my ankle. However; in a stiffer ski boot (limiting the range of ankle motion) while skiing through deep moguls requires moving the feet forward as the feet move up the bump and pulled back as they pass down the other side in relation to the cm. In this manner one is able to balance effectively without deeply flexing the ankle.

I don't agree that "good skiers in stiff boots tend to lean forward against them" unless they are out of alignment fore/aft. In this case they have to fight to get to a balanced position causing this symptom. This may be caused by too flat of a zeppa angle and/or a too upright shaft, or/and too flat of a binding angle. Jim Lindsay's article on dorsiflexion explains some of this better than I can. I am afraid sometimes I am not very good at articulating what I understand. The fact though is that strong skiers prefer stiffer boots for a reason...they reward accuracy with accuracy.

bud
post #90 of 131
Quote:
Softer boots will tolerate more inaccuracy but, reward good skiing less than stiffer boots. As Ydnar said, when a boot is properly aligned ankle flexion can be used for tactical skiing rather than trying maintain or find a balanced position. When in a stiffer boot that is well aligned/balanced to the skier and that skier can manage their movements accurately the rewards are great!
Like everything in skiing, I think it depends on the person. As you know, I am a pipsqueak. I skied a stiff men's boot made stiffer by downsizing for most of my adult life--until I met the Dolomite Sintesi junior race boot. In my case, my ability to ski took a giant leap when I went to a softer boot.
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