Crossing over and C.O.M.

[Steve]

Re: ball of foot - paging @Doby Man

 

[Skisailor]

Skiing isn't like all those sports where we are moving about using muscular effort. Quite the contrary, skiing is just standing there at twenty miles an hour and when I am just standing I stand on my whole foot. Maintaining pressure under the ball of the foot is fatiguing when just standing.

Further, I can demonstrate that being on the balls will require more not less movement and effort to accomplish those outcomes we are after than when centered over the arch which is the part of the foot designed to support our weight.

Skiing ain't walking, running and jumping and a lot of what our bodies have learned to master those activities is counter productive to mastering skiing.

uke

I don't know about you, but I don't think of skiing as just standing there while the world slides by at 20 mph. When I ski, I am reacting continually to all kinds of external forces in order to keep myself in balance. That is not at all the same as just standing still and is absolutely akin to every other sport involving movement that humans play.

From the standpoint of optimizing our ability to make balancing movements in any direction at any time, the ball of the foot is the part of the foot that allows us to do this.

 

[JESinstr]

Hi Jilly!!

Yes. And I use teaching for transfer all the time when working on this. We talk about how we wouldn't receive a serve in tennis, or shoot a foul shot, or hit a golf ball or a baseball, etc. etc. from our arch or heels.

Can you explain to us how the concept of transfer (not that I don't appreciate it) would apply if the tennis court, basketball court, or tee box suddenly turned to ice?

 

[Uke]

Can you explain to us how the concept of transfer (not that I don't appreciate it) would apply if the tennis court, basketball court, or tee box suddenly turned to ice?

And was tipped 10 degrees one way.

uke

 

[Skisailor]

And was tipped 10 degrees one way.

uke

Wowee!!!! Sounds like fun!

All the more reason I would want to be balanced over the balls of my feet! That would give me the greatest possibility of staying upright and moving in the direction I want to go.

I sure would hate to be sliding around on an icy tennis court on my heels!

 

[mdf]

I seem to remember seeing a plot of the readings from an array of pressure sensors under the foot inside the ski boot.
But maybe it was just one per foot, so inside vs outside ski. Anybody else remember where that was?

It would be an interesting to have from a couple of bad, good, and great skiers.

 

[mister moose]

Can you explain to us how the concept of transfer (not that I don't appreciate it) would apply if the tennis court, basketball court, or tee box suddenly turned to ice?

Like this????

 

[Jilly]

Like this????

https://giphy.com/embed/SIvcTkusMWS4

Not so sure about that, but!!

If I'm standing and flex my ankles, my weight shifts to the balls of my feet. Nothing happens to my heels. I can feel them in contact with the bed of the shoe.

 

[Uke]

Ice skates are great for dealing with icy surfaces, seems to me that that long flat blade would demand a whole foot stance to best function.

Being on the balls is great for moving forward, not so good for moving laterally, and even less so for moving back.

Careful observation of athletes in almost any sport will show that the ball of the foot is a place to move to and through not a place to hang out on and move from. Power comes from a firmly planted foot not one weakly positioned on the ball of the foot.

Balance is dependent on points of contact. In the foot we have three points of contact, the heel and the inside ball and the outside ball of the fore foot. These three points are also the anchors for the three arches that give the foot its strength and stability. On the ball you lose one of these points and it becomes harder to balance at the same time you are weakening the support mechanism.

We are designed to carry our weight on the center of the foot and move in all directions from that center.

uke

 

[Uke]

Don't know why I'm feeling so wordy today but what the hell.

About the just standing there thing. Whats the reality of skiing if not standing on a platform and moving my body in ways to influence that platform. Throw in the fact that the platform is moving and interacts with the surface it is moving over and is highly designed to control that interaction and you have skiing.

uke

 

[Skisailor]

Ice skates are great for dealing with icy surfaces, seems to me that that long flat blade would demand a whole foot stance to best function.

Being on the balls is great for moving forward, not so good for moving laterally, and even less so for moving back.

Careful observation of athletes in almost any sport will show that the ball of the foot is a place to move to and through not a place to hang out on and move from. Power comes from a firmly planted foot not one weakly positioned on the ball of the foot.

Balance is dependent on points of contact. In the foot we have three points of contact, the heel and the inside ball and the outside ball of the fore foot. These three points are also the anchors for the three arches that give the foot its strength and stability. On the ball you lose one of these points and it becomes harder to balance at the same time you are weakening the support mechanism.

We are designed to carry our weight on the center of the foot and move in all directions from that center
uke

Guess we'll just have to agree to disagree. I posted this recently in a PSIA forum thread after seeing video that was posted here in another of the recent ski school threads. In it, US Ski Team Coach Ron Kipp describes the ball of the foot as "the anatomical and biomechanical optimal place where we are the most agile". I totally agree. Balancing there maximizes our options in any given moment. And in every direction.

 

[graham418]

The last couple of years we have been getting instruction to be "stacked" in our position. Having our joints aligned and supporting most of the load with our skeletal structure instead of the musculature. It is much stronger, more stable position to work from. And a lot less tiring

 

[Skisailor]

The last couple of years we have been getting instruction to be "stacked" in our position. Having our joints aligned and supporting most of the load with our skeletal structure instead of the musculature. It is much stronger, more stable position to work from. And a lot less tiring

Yes! This is what I strive for in my personal skiing (in keeping with my moniker of "laziest skier on the mountain") and also what I teach. There is nothing about centering our weight over the balls of the feet that would preclude a skier from being "stacked" and managing loads and forces with the skeleton rather than with the large muscle groups - which as you say, is much more tiring.

 

[Rod9301]

I think you are confusing weight with pressure on the ski tips.

Weight should be around the arch, so the skis are pressured evenly.

Then bend the ankle to add pressure on the ski tip if desired like in shortening the turn radius.

 

[Uke]

Hate to have so diverted the thread so early so let me try to relate this stance thing to the OP's question.

From time immemorial the progression of pressure from the tip to the tail through the arc has been talked about and taught. This is very good skiing.
Now to achieve this I have to go from feeling pressure on the tail of the old outside ski to feeling pressure on the tip of the new outside ski in the instant of transition. This is much easier for a skier standing on their arch than for one standing on the balls. Those who try to stay on the balls seem to ski with more ski lead and need to make a bigger move in transition to engage the tip of the ski, this move is usually an extension to power the transition. As of 10 or 12 years ago that was Ron's movement pattern. Don't know how it has changed as I haven't seen him ski in that long.

From a centered stance I simply release the old outside ski as the pressure hits the back of the arch (the heel) and feel the tip of the new outside ski engage to pressure the front of the arch (the ball). This flow of pressure is an outcome of the dynamics of the turn not something I have to try to make happen.

uke

 

[Doby Man]

Re: ball of foot - paging @Doby Man

Yes! This is what I strive for in my personal skiing (in keeping with my moniker of "laziest skier on the mountain") and also what I teach. There is nothing about centering our weight over the balls of the feet that would preclude a skier from being "stacked" and managing loads and forces with the skeleton rather than with the large muscle groups - which as you say, is much more tiring.

… as long as we remember “what” we are stacking which is not actually our skeleton so much as it is the CoM and BoS through skeletal joint flexion and, that the “stacking” is always fluid. Essentially, stacking is the alignment of the vector between the CoM and BoS with the constantly changing upward vector of returning ground force reaction that the turn provides. Or, somewhat similar to what specific tilt you should hold your snow cone under a 2:00 sun with a 15 mph North North East breeze on an 82 degree day with 60% humidity and 42K south of the equator in mid september (it could be late sept., we don’t have to be too specific).

@Uke, I agree with most of your points but you can’t have pressure over the ball of the inside foot with inside tip lead which is biomechanically impossible. Inside tip lead is directly representative of pressure over the inside heel which is disabling to inside ski contribution.

There are many views regarding how pressure over the sole of the foot comes into play. Personally, I look at the ball of the foot as a base of leverage and the heel as the base of support. When I engage my shovel in turn phase one, I do it from the center of the ski which is under the ball of the foot. When I start the turn over the ball of the foot, it settles back a touch for more stability during dorsiflexion in turn phase three. There is no heel lifting as that is never required from migratory pressure over the sole of the foot. When more pressure is over the ball of foot during plantar flexion (which is extension for skiing), the metatarsal lever is activated and dynamic which gives mobility to the ankle. The plantar flexion and ball of foot pressure also allows the skier to access pressure between the front of the ankle (top of navicular bone directly over the instep) and that part of the boot for more shovel pressure and tipping leverage. You can’t access navicular pressure (lateral or frontal) when dorsiflexed. If your heel comes up when plantar flexing the navicular into the front of the boot, the boot does not fit correctly.

While being on the ball of the foot may feel destabilizing, that is when the ankle has the freedom to invert into the turn and gets the BoS to move laterally under the CoM. However, when we move that balance point back a touch in phase two and more in phase three, the ankle straightens out (everts to neutral) along with dorsiflexion, we see less ankle mobility and more ankle stability that will be needed for the greater forces at play in phase three.

The ankle goes from offering lateral mobility for inversion during plantar flexion in phase one and leveraging the ski into the turn and then offering more stability as it straightens out laterally during dorsiflexion in phase two then more so in three where the turning forces are greatest. This fore to aft application of the foot allows for the mobility and stability we need from the ankle in different parts of the turn. We need that overlapping combination of mobility and stability to create turning leverage over the ski.

Skiers who remain centered on the same spot over the sole of the foot miss out on some or much of the fore to aft carving application of the ski which provides more carving penetration into hard surfaces as well as can further tighten the arc of the pure carved turn on the steeps for speed control without friction as we concentrate pressure from the shovel then to the tail of the ski. When we see WC SL’ers bending the shovel only in phase one, they are delicately balanced on the front edge of going over the handlebars and are exhibiting a highly refined fore/aft balance.

The further back you start the turn over the sole of the foot, the less fore aft travel of the CoM the skier has to play with. Because creating leverage requires two or more contact points with the same structure, sole pressure works with cuff pressure to create leverage with which to control the relationship between the CoM and the BoS. The more aft the sole pressure is at the start of the turn, the more the skier must rely on the cuff of the boot. While modern skis allow more turning from one spot than did straight skis, at the arch/heel, it is at the expense of dynamic fluidity. That may work fine on soft snow and gentle slopes but not so much when things get steeper and icyer.

The mechanics and trade-off distribution of accessible mobility and stability of our anatomy and along the kinetic chain changes significantly throughout the turn phases as the compatibly timed and mechanically complementary motor patterns occur:

Phase one: Pressure over ball - plantar flexion - leg extension - inclination - ankle inversion for ski tipping mobility.

Phase two: transition from the above status to the below status:

Phase three: Pressure over arch/heel - dorsiflexion -leg flexion - angulation - ankle eversion to neutral for stability.

See how our natural kinetic chain actually provides a specific path of movement through rotation, flexion/extension and angulation then back to neutral per every turn cycle. It is a consistently packaged set of movement ratios throughout the body that only changes in DIRT based on turn intent. It is that natural path of movement through which the ski speaks upward with its ground force reaction as we remain correctly stacked throughout the turn. As soon as we fall out of that path of movement, or path of alignment, we are notified immediately through that ugly sensation of being out of balance.

Throughout all three phases of the turn, the elements of separation: rotation, angulation, inclination, flexion and extension are/should be in constant fluctuation. The CoM to BoS relationship is in constant flow through the fore/aft, lateral, vertical and rotational planes of movement. Nothing is static, everything is fluid. Drink up.

Something else I find interesting regarding the ball of the foot is that, there is actually an inside ball and an outside ball or, a “little toe side ball” and a “big toe side ball”. I would say that the size difference of the two balls, about 70 - 30, is conveniently close to the actual pressure distribution the little toe edge and the big toe edge that the ski gets in much of the technical freeskiing to which many of us aspire. As well, the little toe side ball is about 20% of the length of the foot aft from the big toe side ball. This makes my ground - up stance position with an inside foot that is over the little toe side ball that is “held” back and pinned down using static gravity top-down flexion and forced to carve and bend the ski with only 10 - 30% of the total pressure. In other words, there is no “pull back” maneuver required that uses hamstring contraction that can get in the way of a loosely flexing stack from top to bottom. This is an example of lowering the kinesthesis to the foot and ankle, a constant tension that drives the ski directly through the boot. To me the key to good skiing is the “automation” of of movement patterns that require less muscular effort but also less focus and management of the details. It is “gravity” powered and drives the inside ski into service. That said, I believe that muscularly activated “pull back” dorsiflexion (inside or both skis) is an excellent correctional, developmental and tactical accessory motor pattern depending on the scenario.

 

[skier]

Being forward means having more pressure on the ski shovel than the tail. Being back means more pressure on the tail than the shovel, and being centered would have equal pressure on the tail and shovel. Ski boots are not designed for us to stand up straight; therefore it's impossible to support our weight with our skeletal structure just by balancing on our feet. Try squatting in the ski boot position for an extended period of time and you will feel some serious burn. Forward or back on your foot still creates lots of leg burn as long as your legs are bent. The only way to shift some of that stress off your muscles and onto your skeleton is to put pressure on the tongue of the boot with your shins. Also, by putting pressure on the tongue, pressure is applied to the ski shovel and you are forward. Pressure on the tail makes it very difficult to turn a ski. Pressure on the shovel makes it easy to turn a ski, especially if you want to bend the tip for a tighter turn. So, being forward is the only way to ski with minimal muscular effort and still have maximum ability to turn a ski, which is one reason that mogul coaches teach constant shin pressure. Some may experience their tails washing out with shin pressure, but that's largely dependent on the type of skis and boots. For skis that need less forward pressure to carve smoothly, there are boots that are stiffer and more upright.

 

[Skisailor]

… as long as we remember “what” we are stacking which is not actually our skeleton so much as it is the CoM and BoS through skeletal joint flexion and, that the “stacking” is always fluid. Essentially, stacking is the alignment of the vector between the CoM and BoS with the constantly changing upward vector of returning ground force reaction that the turn provides. Or, somewhat similar to what specific tilt you should hold your snow cone under a 2:00 sun with a 15 mph North North East breeze on an 82 degree day with 60% humidity and 42K south of the equator in mid september (it could be late sept., we don’t have to be too specific).

@Uke, I agree with most of your points but you can’t have pressure over the ball of the inside foot with inside tip lead which is biomechanically impossible. Inside tip lead is directly representative of pressure over the inside heel which is disabling to inside ski contribution.

There are many views regarding how pressure over the sole of the foot comes into play. Personally, I look at the ball of the foot as a base of leverage and the heel as the base of support. When I engage my shovel in turn phase one, I do it from the center of the ski which is under the ball of the foot. When I start the turn over the ball of the foot, it settles back a touch for more stability during dorsiflexion in turn phase three. There is no heel lifting as that is never required from migratory pressure over the sole of the foot. When more pressure is over the ball of foot during plantar flexion (which is extension for skiing), the metatarsal lever is activated and dynamic which gives mobility to the ankle. The plantar flexion and ball of foot pressure also allows the skier to access pressure between the front of the ankle (top of navicular bone directly over the instep) and that part of the boot for more shovel pressure and tipping leverage. You can’t access navicular pressure (lateral or frontal) when dorsiflexed. If your heel comes up when plantar flexing the navicular into the front of the boot, the boot does not fit correctly.

While being on the ball of the foot may feel destabilizing, that is when the ankle has the freedom to invert into the turn and gets the BoS to move laterally under the CoM. However, when we move that balance point back a touch in phase two and more in phase three, the ankle straightens out (everts to neutral) along with dorsiflexion, we see less ankle mobility and more ankle stability that will be needed for the greater forces at play in phase three.

The ankle goes from offering lateral mobility for inversion during plantar flexion in phase one and leveraging the ski into the turn and then offering more stability as it straightens out laterally during dorsiflexion in phase two then more so in three where the turning forces are greatest. This fore to aft application of the foot allows for the mobility and stability we need from the ankle in different parts of the turn. We need that overlapping combination of mobility and stability to create turning leverage over the ski.

Skiers who remain centered on the same spot over the sole of the foot miss out on some or much of the fore to aft carving application of the ski which provides more carving penetration into hard surfaces as well as can further tighten the arc of the pure carved turn on the steeps for speed control without friction as we concentrate pressure from the shovel then to the tail of the ski. When we see WC SL’ers bending the shovel only in phase one, they are delicately balanced on the front edge of going over the handlebars and are exhibiting a highly refined fore/aft balance.

The further back you start the turn over the sole of the foot, the less fore aft travel of the CoM the skier has to play with. Because creating leverage requires two or more contact points with the same structure, sole pressure works with cuff pressure to create leverage with which to control the relationship between the CoM and the BoS. The more aft the sole pressure is at the start of the turn, the more the skier must rely on the cuff of the boot. While modern skis allow more turning from one spot than did straight skis, at the arch/heel, it is at the expense of dynamic fluidity. That may work fine on soft snow and gentle slopes but not so much when things get steeper and icyer.

The mechanics and trade-off distribution of accessible mobility and stability of our anatomy and along the kinetic chain changes significantly throughout the turn phases as the compatibly timed and mechanically complementary motor patterns occur:

Phase one: Pressure over ball - plantar flexion - leg extension - inclination - ankle inversion for ski tipping mobility.

Phase two: transition from the above status to the below status:

Phase three: Pressure over arch/heel - dorsiflexion -leg flexion - angulation - ankle eversion to neutral for stability.

See how our natural kinetic chain actually provides a specific path of movement through rotation, flexion/extension and angulation then back to neutral per every turn cycle. It is a consistently packaged set of movement ratios throughout the body that only changes in DIRT based on turn intent. It is that natural path of movement through which the ski speaks upward with its ground force reaction as we remain correctly stacked throughout the turn. As soon as we fall out of that path of movement, or path of alignment, we are notified immediately through that ugly sensation of being out of balance.

Throughout all three phases of the turn, the elements of separation: rotation, angulation, inclination, flexion and extension are/should be in constant fluctuation. The CoM to BoS relationship is in constant flow through the fore/aft, lateral, vertical and rotational planes of movement. Nothing is static, everything is fluid. Drink up.

Something else I find interesting regarding the ball of the foot is that, there is actually an inside ball and an outside ball or, a “little toe side ball” and a “big toe side ball”. I would say that the size difference of the two balls, about 70 - 30, is conveniently close to the actual pressure distribution the little toe edge and the big toe edge that the ski gets in much of the technical freeskiing to which many of us aspire. As well, the little toe side ball is about 20% of the length of the foot aft from the big toe side ball. This makes my ground - up stance position with an inside foot that is over the little toe side ball that is “held” back and pinned down using static gravity top-down flexion and forced to carve and bend the ski with only 10 - 30% of the total pressure. In other words, there is no “pull back” maneuver required that uses hamstring contraction that can get in the way of a loosely flexing stack from top to bottom. This is an example of lowering the kinesthesis to the foot and ankle, a constant tension that drives the ski directly through the boot. To me the key to good skiing is the “automation” of of movement patterns that require less muscular effort but also less focus and management of the details. It is “gravity” powered and drives the inside ski into service. That said, I believe that muscularly activated “pull back” dorsiflexion (inside or both skis) is an excellent correctional, developmental and tactical accessory motor pattern depending on the scenario.

Good stuff Doby Man. I agree with alot of the points you made above. I'm well aware that the current cat's pajamas is the idea of migrating from ball to arch/heel during turns. It's certainly a way of making turns that lots of really good skiers are using. I just don't subscribe to the notion of letting my CoM drift back relative to the BoS in every turn. It's less efficient. It's more tiring. It requires a bigger movement to come forward again at the start of each turn. It puts me on my heels for a larger proportion of time in each turn - not a great place to be to handle unexpected forces due to terrain or conditions. Do I employ that technique occasionally? Sure.
Do I want to do that intentionally from turn to turn to turn? Heck no.

 

[Uke]

Doby,

You missed my point a little or I was sloppy in my description. I wasn't talking about pressure on the ball when the ski is still on the inside but the pressure that appears the instant that that ski changes roles and becomes the outside ski. Pressure on that ski goes from very light heel pressure to nothing (the moment of release) to building pressure on the fore foot.

Also, don't have snow to try it but I'm pretty sure I could pressure the ball of the inside foot with tip lead. It might be awkward and not something I would want to do but probably possible.

uke

 

[Kneale Brownson]

Open the knee joint while closing the ankle joint.