Center of Mass is NOT a body part nor in a fixed location!

[Ursula]

This conversation happened over 20 years ago in Big Sky, MT. The well known lady of the CoM movement came to the mountain to tell us her gospel about all women need the binding mounted forward and heel lifts stuffed into their boots.
She gave her talk about how all of us women, as soon as we go through puberty, would get the big behinds and therefore have a lower center of mass than men. Our ski school still used stretch pants as part of our uniforms and one of our male instructors pointed at me and said: Does that mean she has not been through puberty yet???? ( I weighed about 13o lbs at 5'6" and was wearing size XS in long,) She looked at me and said: well - there are some exceptions.....
Then she continued her spiel about the heel lifts. I sort of just curled back my eyeballs and listened to the rest. At the end of her talk, she came up to me, looked at my name tag and asked: Ursula, it looks like you don't agree with my assessment.
I asked her a simple question: If your theory would be correct, and women would need heel lifts to be able to get forward, how can you explain why the pro female golfers or pro female tennis players are NOT playing their sports in heels? As far as I know they all play in flat shoes and are perfectly able to get their weight forward!
She looked at me and said: Well, hmmm, ahhh, well, they flex their joints.
My response was: I rest my case! All we need is FLEX our joints to move the CoM forward.

So, repeat as necessary: you can move your Center of Mass by flexing joints.
You can center your weight over your heels, you can center your weight over your toes and any square inch in between. It will be YOUR choice!

If you want to ski with your weight over your heels, better make sure you do LOTS of squads to get in shape for ski season. If you keep your weight over your balls of your feet while you ski, you won't have to worry about that because your quads don't have to work as much. (We can play an hour of tennis or more and never have to tell the person on the other side to hold the next ball for a while because our quads are killing us. Why not? Because we can't lean back. There is no ski tail that would keep us upright. We would fall over. And we would not be ready to run for the ball.)

In studies (just search for it on the internet) folks have determined the fact that the average difference of male versus female CoM is less than an inch lower in women compared to men. That is stretched out flat on a board with your arms beside you.
Now if the women would have all lifted their arms over their heads, but the men would have kept their arms on their sides, the result of this measurement would have been different. Why? Because the women moved mass higher up on their torso.



My conclusion:
If you are happy with your heel lifts, be happy.
As long as you can flex joints, move arms from your side towards the front of your body, you can get your weight forward. As a matter of fact, you can get forward with your weight if you keep your hands BEHIND you. You just have to flex forward more in your hip socket. Just watch speed skaters. They ARE forward with their weight but keep the arms behind in certain parts of a race.

In my experience of over 40 years of teaching skiing, I can attest to that most of folks, male or female, that have a big forward lean in their boots, end up in the back seat for most of their skiing.
But have I put folks on heel lifts? Yes. Limited dorsi flexion or ill fitting boots, too big of boots, but no money to buy new ones come to mind. But definitely NOT for getting the weight forward. As long as you have a functioning hip socket, you CAN get your weight forward.

I hope this helps.
Ursula

 

[Ursula]

For interested folks: https://hypertextbook.com/facts/2006/centerofmass.shtml

 

[Jilly]

Thank you Ursula....We talked about this at our Women's Edge Camp last week. And since most of us were on unisex skis, mounting the binding forward was a moot point. I don't think anyone in my group had heel lifts either.

I will admit that I tried heel lifts back in the 90's after hearing the same spiel. Fast forward to a Rossi boot that made me feel like I was skiing in high heels.....never again.

I like your take on golf or tennis...need to remember that when someone starts the heel lift spiel with me.

 

[Mary Tee]

This is so interesting. In 2000 I went to a seminar, same well known COM guru, and bought in hook line and sinker! The last time I got new boots and had my first real fitting from Shon at the Boot Pro in Ludlow, I told him I needed lifts, and he asked why I thought that. I said I thought all women needed them. He disagreed, and told me to ski them, and come back if I had any problem. I have no recollection of going back for the lifts! I will have to look. However, the last time I went to PT for a back issue, the Therapist had me touch my toes, which I have no problem doing, and his comment was that I didn't hinge from my hip like most people, that I came forward, sort of out of the hip, and then down. When I asked what that meant, he said nothing really, not a problem, just different. So Ursula, do you think this difference in the way my hip hinges has any impact on my skiing, and my need / lack of need of lifts? Also, I am starting to demo skis. I am pretty sure my old lotta luvs have forward mounted bindings...now you have me wondering if that is necessary as well.
Maybe I need to come out to you for Advice!!!

 

[Obrules15]

This conversation happened over 20 years ago in Big Sky, MT. The well known lady of the CoM movement came to the mountain to tell us her gospel about all women need the binding mounted forward and heel lifts stuffed into their boots.
She gave her talk about how all of us women, as soon as we go through puberty, would get the big behinds and therefore have a lower center of mass than men. Our ski school still used stretch pants as part of our uniforms and one of our male instructors pointed at me and said: Does that mean she has not been through puberty yet???? ( I weighed about 13o lbs at 5'6" and was wearing size XS in long,) She looked at me and said: well - there are some exceptions.....
Then she continued her spiel about the heel lifts. I sort of just curled back my eyeballs and listened to the rest. At the end of her talk, she came up to me, looked at my name tag and asked: Ursula, it looks like you don't agree with my assessment.
I asked her a simple question: If your theory would be correct, and women would need heel lifts to be able to get forward, how can you explain why the pro female golfers or pro female tennis players are NOT playing their sports in heels? As far as I know they all play in flat shoes and are perfectly able to get their weight forward!
She looked at me and said: Well, hmmm, ahhh, well, they flex their joints.
My response was: I rest my case! All we need is FLEX our joints to move the CoM forward.

So, repeat as necessary: you can move your Center of Mass by flexing joints.
You can center your weight over your heels, you can center your weight over your toes and any square inch in between. It will be YOUR choice!

If you want to ski with your weight over your heels, better make sure you do LOTS of squads to get in shape for ski season. If you keep your weight over your balls of your feet while you ski, you won't have to worry about that because your quads don't have to work as much. (We can play an hour of tennis or more and never have to tell the person on the other side to hold the next ball for a while because our quads are killing us. Why not? Because we can't lean back. There is no ski tail that would keep us upright. We would fall over. And we would not be ready to run for the ball.)

In studies (just search for it on the internet) folks have determined the fact that the average difference of male versus female CoM is less than an inch lower in women compared to men. That is stretched out flat on a board with your arms beside you.
Now if the women would have all lifted their arms over their heads, but the men would have kept their arms on their sides, the result of this measurement would have been different. Why? Because the women moved mass higher up on their torso.

View attachment 6554

My conclusion:
If you are happy with your heel lifts, be happy.
As long as you can flex joints, move arms from your side towards the front of your body, you can get your weight forward. As a matter of fact, you can get forward with your weight if you keep your hands BEHIND you. You just have to flex forward more in your hip socket. Just watch speed skaters. They ARE forward with their weight but keep the arms behind in certain parts of a race.

In my experience of over 40 years of teaching skiing, I can attest to that most of folks, male or female, that have a big forward lean in their boots, end up in the back seat for most of their skiing.
But have I put folks on heel lifts? Yes. Limited dorsi flexion or ill fitting boots, too big of boots, but no money to buy new ones come to mind. But definitely NOT for getting the weight forward. As long as you have a functioning hip socket, you CAN get your weight forward.

I hope this helps.
Ursula

There are limitations to this depending on the proportions of the person you are dealing with. My head does not clear my knees when I completely fold my top half down until it is flush to my things. Plenty of flexibility. My bootfitter laughed at me last week and said proportionately I had the longest thighs she'd ever seen.

Still stands that there is no *everybody needs*, or *nobody needs*. People need to be evaluated on an individual basis, because the person with the second longest thighs per my bootfitter is a guy.

 

[Abbi]

This is so interesting. In 2000 I went to a seminar, same well known COM guru, and bought in hook line and sinker! The last time I got new boots and had my first real fitting from Shon at the Boot Pro in Ludlow, I told him I needed lifts, and he asked why I thought that. I said I thought all women needed them. He disagreed, and told me to ski them, and come back if I had any problem. I have no recollection of going back for the lifts! I will have to look. However, the last time I went to PT for a back issue, the Therapist had me touch my toes, which I have no problem doing, and his comment was that I didn't hinge from my hip like most people, that I came forward, sort of out of the hip, and then down. When I asked what that meant, he said nothing really, not a problem, just different. So Ursula, do you think this difference in the way my hip hinges has any impact on my skiing, and my need / lack of need of lifts? Also, I am starting to demo skis. I am pretty sure my old lotta luvs have forward mounted bindings...now you have me wondering if that is necessary as well.
Maybe I need to come out to you for Advice!!!

And I went out (from the same place and fitter) without the lifts, came back after not being able to manage at all and got the lifts. Possibly because I have had them for years, so I am used to them, so needed them to feel the same.

But yes to all responses. If you are good without them, or good with the, all good as long as you are out there!

 

[Obrules15]

This conversation happened over 20 years ago in Big Sky, MT. The well known lady of the CoM movement came to the mountain to tell us her gospel about all women need the binding mounted forward and heel lifts stuffed into their boots.
She gave her talk about how all of us women, as soon as we go through puberty, would get the big behinds and therefore have a lower center of mass than men. Our ski school still used stretch pants as part of our uniforms and one of our male instructors pointed at me and said: Does that mean she has not been through puberty yet???? ( I weighed about 13o lbs at 5'6" and was wearing size XS in long,) She looked at me and said: well - there are some exceptions.....
Then she continued her spiel about the heel lifts. I sort of just curled back my eyeballs and listened to the rest. At the end of her talk, she came up to me, looked at my name tag and asked: Ursula, it looks like you don't agree with my assessment.
I asked her a simple question: If your theory would be correct, and women would need heel lifts to be able to get forward, how can you explain why the pro female golfers or pro female tennis players are NOT playing their sports in heels? As far as I know they all play in flat shoes and are perfectly able to get their weight forward!
She looked at me and said: Well, hmmm, ahhh, well, they flex their joints.
My response was: I rest my case! All we need is FLEX our joints to move the CoM forward.

So, repeat as necessary: you can move your Center of Mass by flexing joints.
You can center your weight over your heels, you can center your weight over your toes and any square inch in between. It will be YOUR choice!

If you want to ski with your weight over your heels, better make sure you do LOTS of squads to get in shape for ski season. If you keep your weight over your balls of your feet while you ski, you won't have to worry about that because your quads don't have to work as much. (We can play an hour of tennis or more and never have to tell the person on the other side to hold the next ball for a while because our quads are killing us. Why not? Because we can't lean back. There is no ski tail that would keep us upright. We would fall over. And we would not be ready to run for the ball.)

In studies (just search for it on the internet) folks have determined the fact that the average difference of male versus female CoM is less than an inch lower in women compared to men. That is stretched out flat on a board with your arms beside you.
Now if the women would have all lifted their arms over their heads, but the men would have kept their arms on their sides, the result of this measurement would have been different. Why? Because the women moved mass higher up on their torso.

View attachment 6554

My conclusion:
If you are happy with your heel lifts, be happy.
As long as you can flex joints, move arms from your side towards the front of your body, you can get your weight forward. As a matter of fact, you can get forward with your weight if you keep your hands BEHIND you. You just have to flex forward more in your hip socket. Just watch speed skaters. They ARE forward with their weight but keep the arms behind in certain parts of a race.

In my experience of over 40 years of teaching skiing, I can attest to that most of folks, male or female, that have a big forward lean in their boots, end up in the back seat for most of their skiing.
But have I put folks on heel lifts? Yes. Limited dorsi flexion or ill fitting boots, too big of boots, but no money to buy new ones come to mind. But definitely NOT for getting the weight forward. As long as you have a functioning hip socket, you CAN get your weight forward.

I hope this helps.
Ursula

I'm just begging you instructors to *look* at your students and also evaluate their proportions while haranguing them to get forward and flex their joints. For all you know only the people you were right about kept skiing so you know that they were successful.

It could have been that people you were wrong about just quit (like me), discouraged and hurt because instructors were not helpful and gave the same useless advice (useless for me) time and time again. It's very likely in general that people who are predisposed to ski well, continue to ski.

If we all improve our understanding of the biomechanics at work and the interchange between joint movement, proportions, binding ramp delta, boot ramp angle, heel lifts, etc. we improve the sport.

Being too far back on your heels after heel lifts can be a symptom of too much heel lift, too much boot forward lean, too much binding ramp delta, or too much boot ramp angle, or some combination of the four. It's not what those things do, it just means it's too much. Fixing any one can fix the problem expecially if you understand the setup.

Ramp angle leans you forward and moves your center of mass forward with out changing your boot geometry. It works well for people who's femur/lower leg proportions are high and have short torsos and relatively long femurs. Too much and you will reactively lean back. Can cause increased quad burn.

Bindings are all different and there is no standard and no standard reporting. Tyrollia PRX bindings have 8mm of Ramp Delta, PRD have 5mm. The bindings (from another thread) that one of our members was struggling with had 7mm. The old volkl bio-logic setup gave negative ramp delta. Knee bindings give you the option of 3mm or 6mm of Ramp Delta. New women's Atomic Vantage skis have + ramp delta of unknown quantity.

Heel lifts lean you forward but bend your foot at the ball and open up your ankle joint and cause you to be relatively more upright in whatever boot you are in so they work well in people with limited dorsiflexion. Too much you will reactively lean back. If you have a high arch they can cause increased pain because they decrease the available space for your arch.

Reverse binding ramp delta or toe shims can help center people who need heel lifts for the increased dorsiflexion or are in boots with too much forward lean and are therefore sitting back or are in some of these bindings with too much + RA.

Lange Boots have 12 degrees of forward lean and they advertise a natural stance, Head Boots have 16 degrees of forward lean. They both have 4 degrees of ramp angle in the boot. Dodge boots have variable forward lean. I don't know about other brands.

Too much for your particular anatomy or geometry can push you too far forward, cause you to reactively lean back, and decrease the available dorsiflexion you can access in your ankle. Too little can keep you centered behind too far back and require too much boot flex to move forward. Solid sole boots can usually be modified to adjust ramp delta by about +/- 8mm. Comfort soles can usually be adjusted +/- 3mm. Higher the forward lean more the quad burn.

Boots that are too big will decrease the amount your leg is leaning forward, no matter what the actual cuff angle is. A tightly buckled cuff will make the angle more upright as well, as compared to a loose cuff. As liners pack out and the cuffs are tightened down it will pull your lower leg straighter relative to where it was before the packout.

Please lets try to learn these things and how they interact instead of making it about right/wrong, good/bad, my way or the highway. It's really not that difficult. It would be nice if we could also keep track of what the different skis and manufacters were doing so if someone change a setup and had a problem we had a database here where they could look up their bindings or boots. Every bit of information I provided above was acquired the hard way. It would be nice if we could pool data for future use.

All or none, always and never, are *never* (almost never) good ways to approach anything.

What I wrote was acquired over my years of trying to fix me, so is specific to things I've used. What other data do members have that might be helpful?

 

[bounceswoosh]

I honestly think @Ursula and @Obrules15 are saying the same thing. In all of the posts I see acknowledgement that not everyone needs the same setup.

 

[Obrules15]

I honestly think @Ursula and @Obrules15 are saying the same thing. In all of the posts I see acknowledgement that not everyone needs the same setup.

Yes-ish, I'm responding to the sentiment that "everyone can get forward if they learn to flex their joints". I would amend that to "most everyone can get forward if they learn to flex their joints".

 

[mustski]

I was "diagnosed" by a boot fitter as having limited dorsiflexion and then suffered heel lifts for 2 seasons with a myriad of new problems. The best decision I ever made (in ski terms) was to rip those babies out. They completely screwed up my skiing and caused me much foot pain.! I don't know how "limited" my dorsiflexion really is, but I do better without junk underfoot.

 

[Skisailor]

Yes-ish, I'm responding to the sentiment that "everyone can get forward if they learn to flex their joints". I would amend that to "most everyone can get forward if they learn to flex their joints".

Agreed. I think the disconnect comes over the concern about sweeping gender-based generalizations that many involved in various aspects of the ski industry seems to be making.

The concern I have is that they are marketing certain concepts and products as though they should be used by many, if not most, women skiers, when in reality, they are things which should be used only by the relatively few who cannot "get forward by learning to flex their joints".

In my view, the harm to the majority of unsuspecting women skiers is currently disproportionate to the potential benefits for a relative few. I am questioning the widespread use of these things - not suggesting that they can never be helpful.

 

[bounceswoosh]

Heel lifts seem to help me. Instructors generally say I have good fore/aft balance (with the lifts) - including my current one who's scrutinizing me. I was very suspicious of them, but ... sometimes they help. They also have to be the correct size, which I'm sure is a science in itself.

 

[Obrules15]

Agreed. I think the disconnect comes over the concern about sweeping gender-based generalizations that many involved in various aspects of the ski industry seems to be making.

The concern I have is that they are marketing certain concepts and products as though they should be used by many, if not most, women skiers, when in reality, they are things which should be used only by the relatively few who cannot "get forward by learning to flex their joints".

In my view, the harm to the majority of unsuspecting women skiers is currently disproportionate to the potential benefits for a relative few. I am questioning the widespread use of these things - not suggesting that they can never be helpful.

That's why I feel like lack of knowledge is the biggest problem. If you blanket *everyone* needs or *doesn't need* for almost anything, you do a disservice. If we don't understand the physics and biomechanics we can't problem solve or innovate.

We've had a thread where a member inadvertantly had trouble because of a binding ramp angle and it took her forever to get sorted out. I didn't mention it because I'm unfamiliar with it's effects but mount point is another thing that can get arbitrarily played with and it strongly affects a skier.

IMHO The biggest travesty is that people just throw around heel lifts, arbitrarily change mounting points, move people between boots, and throw on bindings without understanding or addressing what these things can do, and seem to have no understanding of how they work together.

I've heard many people buy new boots and the salesperson just moves over their lift without a second thought. Problem is, the new boot geometry might change the need for a lift, or change the size needed. If you've been in an upright boot and switch to one w/ more forward lean you might end up leaning back.

Is the problem here the lift or the fact that the sales person didn't know that changing from a boot with 12 degrees of forward lean to 16 degrees of forward lean causes profound stance effects that might need to be addressed.

If you are getting new skis/bindings, that might change what you need. If you've always skied on a ski with a delta of 7mm and change to a binding with 2 mm of delta that's going to change your stance.

Think about a new skier, excited, goes out and buys a bunch of new equipment. Say she gets the women specific Atomic Skis that have + ramp angle and she goes to a boot retailer and gets her boot set up for a woman (heel lift) and it so happens that she gets a boot with a lot of forward lean. She's so messed up 'til it's not even funny. But even a basic understanding that maybe if your skis have + ramp angle, a heel lift is probably unnecessary seems to be lacking.

The problem here again is not the heel lift but the lack of knowledge.

Even worse another female has had her boots dialed in and she's found the exact right amount of heel lift or forward lean for herself and her skiing progresses. She, excited by her progress buys an advanced women specific ski and can't ski anymore. She's not sophisticated enough to realize that that ski took all of her well loved lift or +RA away because the ski was created to have -RA. All she knows is she can't ski anymore on an advanced ski, so it must mean she sucks.

There are too many variables to this stance thing to successfully categorize anything as something all women do or do not need. I think our only hope is to understand the variables and the effects of over and under compensating. Let's become aware of what to watch for when new skis are purchased or new boots are broken out. Right now, we suck at this.

My current set up (which would be a disaster for most people), is a 16 degree forward lean boot (with spoiler) with a 1 cm heel lift. I just changed from bindings with 6mm of ramp delta to bindings with 8 mm of ramp delta. When I ski over the next two weeks I'm going to be thinking about whether I need less of a heel lift due to the increase in RA or if the spoiler should come off or if I should drop down to a binding with 5mm of RA. I don't know the answer but since I know my setup and my options, if my skiing becomes disastrous I know what to do.

We don't think like that for the most part, but we're smart cookies, we can become aware if we want. One of the coolest things I've seen in the past week was the multiple requests that binding ramp delta be added to published data (asked to be passed on to SIA Reps). That's us taking responsibility for knowing our own setups and being aware of how things work.

 

[Obrules15]

I was "diagnosed" by a boot fitter as having limited dorsiflexion and then suffered heel lifts for 2 seasons with a myriad of new problems. The best decision I ever made (in ski terms) was to rip those babies out. They completely screwed up my skiing and caused me much foot pain.! I don't know how "limited" my dorsiflexion really is, but I do better without junk underfoot.

But that's the thing, it may not have anything to do with your dorsiflexion. Heel lifts do at least two things. First they open the ankle which can gain ROM, second is they move the COM forward (even if people end up back w/ lifts the lift still moved them forward and they're sitting back to compensate). If your COM was fine and the lift moved you too far forward you'd be screwed. No one talks about these effects but they all throw around heel lifts willy nilly. I think that's irresponsible and a detriment to female skiers.

 

[mustski]

My biggest issue was that the change in position actually lifted my liner/foot in the shell and caused my foot to slip out of the heel cup and forward on my custom footbed, causing pressure points and toe bang. I tightened down on the ankle buckle (3 buckle dalbello) to keep my heel back and that extrapolated into loss of circulation and further issues. Ugh! It was a nightmare!

 

[Abbi]

I have been reading, thinking about a corrective cue I was given out skiing on Friday (that helped) and something said in the boot shop. I just dropped off my boots to have the amount of heel lift decreased. That said, now I need any bright cues to keep in my head to stay forward on my skis. I wasn't brave enough to pull the every bit of lift out. Baby steps for me while I evaluate!

Never boring around here!

 

[Mary Tee]

I have been reading, thinking about a corrective cue I was given out skiing on Friday (that helped) and something said in the boot shop. I just dropped off my boots to have the amount of heel lift decreased. That said, now I need any bright cues to keep in my head to stay forward on my skis. I wasn't brave enough to pull the every bit of lift out. Baby steps for me while I evaluate!

Never boring around here!

I will be really interested to hear your results...keep us posted.

 

[Skisailor]

I have been reading, thinking about a corrective cue I was given out skiing on Friday (that helped) and something said in the boot shop. I just dropped off my boots to have the amount of heel lift decreased. That said, now I need any bright cues to keep in my head to stay forward on my skis. I wasn't brave enough to pull the every bit of lift out. Baby steps for me while I evaluate!

Never boring around here!

Some things to play with:

Come forward in your hip socket until your shoulders are over your toes. Then think about bending your ankles first when you are flexing - not knees -(i.e. Sink into the cuff of the boot so that shoulders stay over toes). Experiment with keeping the top buckle of your boot and your power strap relatively loose so that the shaft of your leg can move a bit inside the cuff - making movement of the ankle a little easier since it is not encountering constant resistance.

Use your body weight to flex the boot. It won't happen if you are trying to flex it with just your leg muscle strength.

 

[Abbi]

Some things to play with:

Come forward in your hip socket until your shoulders are over your toes. Then think about bending your ankles first when you are flexing - not knees -(i.e. Sink into the cuff of the boot so that shoulders stay over toes). Experiment with keeping the top buckle of your boot and your power strap relatively loose so that the shaft of your leg can move a bit inside the cuff - making movement of the ankle a little easier since it is not encountering constant resistance.

Use your body weight to flex the boot. It won't happen if you are trying to flex it with just your leg muscle strength.

We shall see! I teach fitness (Pilates, used to be personal trainer) and it makes me nuts when I KNOW what I'm doing wrong but can't figure it out. Type A, much?!

 

[Skisailor]

We shall see! I teach fitness (Pilates, used to be personal trainer) and it makes me nuts when I KNOW what I'm doing wrong but can't figure it out. Type A, much?!

Lol! Well - it's just a snapshot, but looking at your Avatar, you could definitely use a lot more ankle flexion and less knee bend to get those shoulders forward over the toes.

Have fun playing with it!!