Pilates rotating discs for femur rotation training?

[Steve]

Upside down for perspective. It does tip the feet.

 

[LiquidFeet]

OK, so after playing with these, first I put them on a carpeted slant board I made. Then I thought, this doesn't account for long leg, short leg and put them on a balance board that I have, that on top of the slant board!

It's not connected, very hard to get onto, but once on it, it actually works. It does in effect create excessive inside ski tip lead, so as @LiquidFeet has said it would be nice for them to be able to slide fore/aft as well lol!

Check out the pictures:

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Oh that is so clever. Waaay better than the kitchen floor and bar stools.

 

[TheArchitect]

OK, so after playing with these, first I put them on a carpeted slant board I made. Then I thought, this doesn't account for long leg, short leg and put them on a balance board that I have, that on top of the slant board!

It's not connected, very hard to get onto, but once on it, it actually works. It does in effect create excessive inside ski tip lead, so as @LiquidFeet has said it would be nice for them to be able to slide fore/aft as well lol!

Check out the pictures:

View attachment 108012 View attachment 108013 View attachment 108014 View attachment 108015 View attachment 108016 View attachment 108017

I'm very impressed. I did order the disks I posted but if they don't work I'll return them and either look for smaller versions or build ones like you.

 

[trieu]

I had this from my kids' tennis training aid, and have been using this to keep it loose

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[David Chaus]

Oh that is so clever. Waaay better than the kitchen floor and bar stools.

Yeah, but bar stools are pretty cool.

 

[martyg]

I don't know if they come in different sizes, but I found a video of rotator pilates discs and they're pretty large and thus put your feet pretty far apart. For $80, building one like Chris built would be a lot less.

Been thinking about these disc. I'm ordering a pair. So many uses. FYI pelvic floor TA drills can be incorporated into any exercise. You should at any point in a movement, be able to tighten your pelvic floor / TA.

Check out the video in this link. GREAT ROM motion drills for skiing. I'd use the discs to build awareness and hone movement patterns. The exercises in the videos for targeted ROM drills.

 

[Chris Geib]

@Chris, just slide the inside foot back into the place where it belongs, uphill of the other one. Just slide it. Simple. Socks on hard floor are slippery.
Yes, you need your weight mostly on the other foot when you do this. Is that what you want me to say?

Rotate the new inside foot in a pivot slip or skidded turn at initiation, and slide it a week bit back uphill at the skis point out to the side, so your CoM is below it on the hill. Do not slide it back in the direction the heel points, but back sideways, so it ends up lined up just like the disks will have it except it's "back" uphill of you. So you won't fall over. "Back" sideways.

Oh here are words for this. As the new inside foot rotates, slide it "back" towards its little toe edge, sideways as you rotate it to point across the hill. Keep hips pointing downhill-ish.

One more attempt at clarification, assuming words have failed to paint the right picture -- imagine in a pivot slip you are sliding down the hill on two railroad tracks that go down the fall line. Each ski is permanently attached to one of the tracks. Those tracks are hip-width apart. Each ski is allowed to rotate under the back of the arch of its foot while it is sliding downhill on the track. The skis can slide uphill or downhill freely, and rotate freely, but they must stay on the tracks.

Now slide the inside ski up a little as you rotate it so the skis won't bump into each other, and make sure it gets a bit uphill of your CoM, so your CoM is between the skis. Do this with each pivot in a pivot slip. Do it in real turns that you choose to complete. In those real turns, your skis will be traveling along a sideways figure eight beneath you.

Done. This is so hard to say in words. I need a picture. Or a video.

Hi LF,

Not "wanting" you to say anything in particular! Simply curious about how you see this is all.

I understand about the words; I have heard it said that words are a terrible way to communicate Nonetheless, I follow. I think there can be many ways to experience and communicate these. Pivot slips are simple and complicated!

I like to think of pivot slips taking place in neutral with our line of action resolving between our feet and as we rotate the skis more out of the fall line the pressure will bias more to the down hill ski and I can see how your direction to slide the inside foot a wee bit uphill while having more weight on the downhill foot can work and be consistent when carried to snow.

Maybe there are other alternatives? What if we allowed the outside foot to slide down a bit without changing the weight bias from it? If you look at the image of DeAnn you see her outside foot has not turned as far as the inside foot. I experience the same thing as I have greater external rotation than I do internal rotation and the femur of my outside foot reaches end of travel before coming 90* across the fall line, so my outside hip needs to advance that wee bit you speak of so my outside ski can make 90* across the fall line. What if when we reach this end of travel (or the point the skis would start overlapping) we then continue with the rotation we have below the knee and allow the outside ski to flatten a bit more than the inside ski allowing a weathervane effect so the downhill ski advances even though weight is biased there and we allow it to pull the outside hip forward a wee bit as well creating a slightly anticipated position. Naturally we are continuing to apply crank to the outside ski to assist and it can almost feel like the feet pull the hips around slightly.

I feel we can control this more accurately and respond to variations underfoot by modulating edging foot to foot but it is really a combination of both I expect and the line between edging and pressure blurs a bit while slipping down the hill - which cannot be replicated in socks on the hardwood floor.

The words are a bit murky with the CoM bit in this post and the preceding, but we've thrashed this horse before. The CoM needs to move forward and back in response to and/or anticipation of the resistance (or lack of) underfoot. I think we want to maintain our neutral centered resultant at the back of the arch and the CoM (way up there above the feet) may be ahead, over or behind our feet while slipping. Standing on the bus: are we traveling at the same rate as the bus, is the bus accelerating under foot, is the bus decelerating under foot.

I completely agree with the feet on rails! And I appreciated that detail as many in fact rotate the pelvis and put both feet a single rail.

Thank you for taking the time to explain!

Best,

Chris

 

[Chris Geib]

Thanks @Chris Geib I am not very handy, but this took me about ½ hour to make and works great. Small table saw, only 2 kickbacks which fortunately didn't injure me.

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Hi Steve,

Looks like an awesome job to me and I like your bases are bigger. Glad you did not get hurt in the process!

I recommend you move the bearing backward. It looks to me like you are rotating about the the front of your arch and I would prefer the pivot point be under the front of your heel.

Maybe while apart to move increase the chamfer a bit more.

Best,

Chris

 

[Chris Geib]

...It does in effect create excessive inside ski tip lead, so as @LiquidFeet has said it would be nice for them to be able to slide fore/aft as well lol!..

Hi Steve,

How is excessive tip lead created?

Your resulting tip lead would be exactly the distance your feet are apart on the turntables. Same in a pivot slip on snow if you keep your feet on the two rails that @LiquidFeet described. On a slope you might also gain a bit as the leg length difference takes place to accommodate the pitch of the slope and maybe lose a bit as the hips wind in a very slight bit at the end of rotation across the hill.

Net I would expect tip lead to more or less equal the width the feet are apart unless on something stupid steep. But why do pivot slips on a steep slope, that's easy. Pick flatter slopes

Best,

Chris

 

[LiquidFeet]

Hi LF,

Not "wanting" you to say anything in particular! Simply curious about how you see this is all.

I understand about the words; I have heard it said that words are a terrible way to communicate Nonetheless, I follow. I think there can be many ways to experience and communicate these. Pivot slips are simple and complicated!

I like to think of pivot slips taking place in neutral with our line of action resolving between our feet and as we rotate the skis more out of the fall line the pressure will bias more to the down hill ski and I can see how your direction to slide the inside foot a wee bit uphill while having more weight on the downhill foot can work and be consistent when carried to snow.

Maybe there are other alternatives? What if we allowed the outside foot to slide down a bit without changing the weight bias from it? If you look at the image of DeAnn you see her outside foot has not turned as far as the inside foot. I experience the same thing as I have greater external rotation than I do internal rotation and the femur of my outside foot reaches end of travel before coming 90* across the fall line, so my outside hip needs to advance that wee bit you speak of so my outside ski can make 90* across the fall line. What if when we reach this end of travel (or the point the skis would start overlapping) we then continue with the rotation we have below the knee and allow the outside ski to flatten a bit more than the inside ski allowing a weathervane effect so the downhill ski advances even though weight is biased there and we allow it to pull the outside hip forward a wee bit as well creating a slightly anticipated position. Naturally we are continuing to apply crank to the outside ski to assist and it can almost feel like the feet pull the hips around slightly.

I feel we can control this more accurately and respond to variations underfoot by modulating edging foot to foot but it is really a combination of both I expect and the line between edging and pressure blurs a bit while slipping down the hill - which cannot be replicated in socks on the hardwood floor.

The words are a bit murky with the CoM bit in this post and the preceding, but we've thrashed this horse before. The CoM needs to move forward and back in response to and/or anticipation of the resistance (or lack of) underfoot. I think we want to maintain our neutral centered resultant at the back of the arch and the CoM (way up there above the feet) may be ahead, over or behind our feet while slipping. Standing on the bus: are we traveling at the same rate as the bus, is the bus accelerating under foot, is the bus decelerating under foot.

I completely agree with the feet on rails! And I appreciated that detail as many in fact rotate the pelvis and put both feet a single rail.

Thank you for taking the time to explain!

Best,

Chris

Thanks @Chris Geib for getting back to this. It's been fun talking about it.

Yes, the hips do need to rotate at the very end of each pivot in a pivot slip, as this is a physical and anatomical requirement. And yes, one can get the uphill-downhill separation to happen between the feet by allowing the downhill foot to move more downhill instead of having the uphill foot move more uphill (not relative to the snow on the hill but relative to the body). When the skier chooses that alternative, then yes, the skier needs to make sure the CoM moves with that downhill foot to keep more weight on it. If the skier chooses to do it this way, indeed the CoM does end up needing to move fore and aft relative to the feet below it - as you describe in your post.

In my skiing, and where possible in my teaching, I prefer to move the feet around under the CoM rather than move the CoM around over the feet. Both work. Yes, I use both. But as I've worked on building my skiing skills, I've definitely chosen to work more on moving the feet relative to the CoM rather than the other way around. The CoM is my mental frame of reference in my skiing. I keep it as quiet as possible and track its path separate from the path of my feet (keeping the sideways figure eight/infinity sign in mind).

I've realized in recent seasons that this preference puts me in the minority. So be it!

P.S. My breakthrough for doing this came when I read about bringing the feet so far back up under the body at the end of a turn that the next turn happened by default. I tried this and wow what a revelation. This movement accounts for the "do nothing" turn of Bob Barnes, I believe. It's been my go-to for years now.

 

[Rod9301]

Hi Steve,
Net I would expect tip lead to more or less equal the width the feet are apart unless on something stupid steep. But why do pivot slips on a steep slope, that's easy. Pick flatter slopes

Best,

Chris

Minor point, but it's useful to also practice slipping skis on steep terrain.

Sometimes you need to do this. Of course, everyone has a steepness limit, behind which you start side stepping.

 

[LiquidFeet]

True that. But the most difficult pivot slips are on nearly flat terrain in snow you are in, not on. Learning to do pivot slips there is torture, but when bored, why not work on it?

 

[martyg]

Hi Steve,

How is excessive tip lead created?

Your resulting tip lead would be exactly the distance your feet are apart on the turntables. Same in a pivot slip on snow if you keep your feet on the two rails that @LiquidFeet described. On a slope you might also gain a bit as the leg length difference takes place to accommodate the pitch of the slope and maybe lose a bit as the hips wind in a very slight bit at the end of rotation across the hill.

Net I would expect tip lead to more or less equal the width the feet are apart unless on something stupid steep. But why do pivot slips on a steep slope, that's easy. Pick flatter slopes

Best,

Chris

Well.... it depends on your intent. The intent of this device is to train rotation. Pivot slips are the embodiment of that motion and leads to efficient movement patterns in bumps, short radius turns, trees etc.

If you are in a PSIA L2 examine, and demoing pivot slips, we want to see that uphill ski lead. We want to see space between your thighs - because that also shows that your hips are facing down the fall line. No space and it is an axiom that your hips are not facing down the fall line. That shows that rotation is coming from your lumbar - not femurs in hip sockets.

 

[martyg]

Purchased a set. Observations:

- Not for range of motion as others have suggested. If you are after range of motion drills, you need an anchor point.
- This is for training awareness of movement patterns.
- Steve's set-up may serve better utility for ski specific movement patterns. With these discs, for example, I cannot get my feet quite close enough to mimic my on-snow stance for rotational movements. I am more in my carving stance maximizing range of motion for edging. It is a difference of maybe 2" - 3". When the pivot point is under my tibia my toes also hang off the edge. No big deal.
- Super useful for other movements. Great addition to our gym.
- My wife is a full-time trainer. A few of her clients are also private ski students of mine. She has put them on these, and femur rotations without movement of hips / upper body, is extremely challenging for them.
- It will be interesting to see if greater awareness of femur rotation will translate into more efficient forward side slips, and pivot slips, with those people.
- If you want greater range of motion and awareness first do range of motion drills. I have posted a series of them elsewhere. Then get on pivot discs.

Overall a great tool. Maybe not as totally dialed as I would like for very ski specific applications. But very very acceptable. For the $80 or so bucks that I paid it is not worth my time to fabricate.

 

[TheArchitect]

Well.... it depends on your intent. The intent of this device is to train rotation. Pivot slips are the embodiment of that motion and leads to efficient movement patterns in bumps, short radius turns, trees etc.

If you are in a PSIA L2 examine, and demoing pivot slips, we want to see that uphill ski lead. We want to see space between your thighs - because that also shows that your hips are facing down the fall line. No space and it is an axiom that your hips are not facing down the fall line. That shows that rotation is coming from your lumbar - not femurs in hip sockets.

Some of these discussions about technique are hard for me to follow so I appreciate your very clear explanation here. Thanks!

 

[martyg]

Some of these discussions about technique are hard for me to follow so I appreciate your very clear explanation here. Thanks!

My pleasure. Check out the video for. Check out how stable the hips / upper body are. everything happens from the hip sockets down.
There is definitely a benefit to executing pivot slips in a wider corridor. In teaching a bumps progression we teach a forward side slip, to a pivot slip. Ideally we might have some chucky snow. A student forward side slips to the bump / chunk and then pivots on it to change direction. Doing pivot slips in a wider corridor - where you inentiionally have some forward / aft slippage helps build awareness of "center".

Note - skier #2 definately nees to work on range of motion. Most of us - even PSIA D-Team - have injuries / issues to address in this realm. Since bike cares have been cancelled this year my summer has been all about gym workous and range of moion drills for 1 - 2 hours per day. Super excited to get on skis and see how that work translates.

I like to drill pure pivot slips first thing in the AM, on corduroy. I pick a few ridges in the corduroy, and try to keep the distal point of my tibia right on those few ridges - no forward. No back. Looking back on my tracks I can use the visual features of the corduroy and my tracks, to gauge how precise my movements were.

Enjoy.

 

[TheArchitect]

My pleasure. Check out the video for. Check out how stable the hips / upper body are. everything happens from the hip sockets down.
There is definitely a benefit to executing pivot slips in a wider corridor. In teaching a bumps progression we teach a forward side slip, to a pivot slip. Ideally we might have some chucky snow. A student forward side slips to the bump / chunk and then pivots on it to change direction. Doing pivot slips in a wider corridor - where you inentiionally have some forward / aft slipage helps build awareness of "center".

I like to drill pure pivot slips first thing in the AM, on corduroy. I pick a few ridges in the corduroy, and try to keep the distal point of my tibia right on those few ridges - no forward. No back. Looking back on my tracks I can use the visual features of the corduroy and my tracks, to gauge how precise my movements were.

Enjoy.

The mobility exercises one? I did and saved the link.

Edit: Weird. On my screen the text and video I just quoted aren't showing in your original post but here they are. Strange.

Edit 2: Now it's there in the original post. Forum weirdness

 

[martyg]

The mobility exercises one? I did and saved the link.

Yes. If you work range of motion first you will increase flexibility, and get more out of the swivel discs from an awareness standpoint.

That link again to those drills:

 

[Steve]

What’s nice with my device is that I don’t have to rotate my feet/legs. The act of shifting my weight to one side, that leg going down creates the rotation passively.

 

[martyg]

What’s nice with my device is that I don’t have to rotate my feet/legs. The act of shifting my weight to one side, that leg going down creates the rotation passively.

Is that a "good thing"? Do you want this to be assisted? Or do you want to actively engage to capture that sensation? Do you want to build compensation? Or capacity?

It seems that if it happens passively you are not building myelin, and the neurological pathways, as effectively. The more we struggle with a motion, the more robust the myelin sheath becomes, the more accurately it conducts electrical nerve impulses.