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EpicSki › Performance Articles › The Complete Encyclopedia of Skiing—EpicSki Skiing Glossary

The Complete Encyclopedia of Skiing—EpicSki Skiing Glossary  


This project presents a brief and concise glossary of many common skiing and ski teaching concepts, including both contemporary and historical terms. It is by no means a complete list. For more in-depth coverage of these concepts and many more, see the original The Complete Encyclopedia of Skiing, Third Edition, by Bob Barnes, currently available in PDF e-book format through EpicSki.com (PM @Bob Barnes directly).

In addition to brief definitions, this glossary includes a few explanatory images, as well as links to the ever-growing collection of video clips in my Vimeo.com channel, “The Complete Encyclopedia of Skiing.”


Click here to enter the Vimeo.com channel of The Complete Encyclopedia of Skiing.

This article is a living, growing document that I will update regularly as time allows. Much of it was written originally in or before 1998. Modern ski shapes were just coming into the mainstream, and the current trends of freestyle, park and pipe, and “big-mountain” competitions were but distant blips on the radar. New technologies, new techniques, new understanding, and new trends continuously add to the lexicon, while some terms have fallen into disuse or even seen a shift in common meaning. There is much work to be done, and It is a constant labor to keep this document current. Stay tuned!

I welcome suggestions for additional terms, and I encourage discussion of any of these terms and concepts in the forums of EpicSki. Please begin with a post to the thread, The Complete Encyclopedia of Skiing EpicSki Glossary project discussion, but do not hesitate also to start new threads for deeper exploration.

Except where otherwise noted, all opinion and content here, including words, images, animations, and video, is mine alone, and may not represent the opinions of EpicSki.com or any of its representatives or owners—or anyone else, for that matter! Skiing is a fluid, dynamic, and diverse activity, and healthy differences of opinion and perspective not only exist, but provide the basis for vigorous and productive discussion. As I always say in clinics and lessons, do not believe anything I tell you! (And don't believe anything anyone else tells you either. Indeed--question even your own most strongly held beliefs.) It is only through challenging statements and questioning that real understanding develops. Knowledge (merely the bottom rung on the ladder to understanding—see "Bloom's Taxonomy," below) begins with accepting answers. Understanding begins with questions! I welcome the discussion.


Important Note:
Except as specifically noted, all content herein is copyrighted material, with all rights reserved. Also included are certain trademarked terms of PSIA (Professional Ski Instructors of America™) and other entities, as noted. All opinions expressed in this article are exclusively those of the author, and may not represent the policies or opinions of any other person or organization.


“knock-kneed” stance that often indicates insufficient inside leg activity, or a need for canting or boot adjustment

movement of leg or other body part AWAY from a center axis (“legs apart”)

Adduction (body part movement toward a center line) and Abduction (movement away from a center line).

Unlike “skills,” which are learned, abilities involve both learned and innate components and are less specific to a particular activity; think “skiing skills” but natural “athletic ability”

Ability Level
How good are you? What is an "expert"? These questions are so subjective that they are impossible to answer definitively. But ski schools have long attempted to classify skiing ability as objectively as possible, primarily to simplify the process of placing students in the right classes. PSIA has adopted a 1-9 level description hoping to standardize the process, but many ski schools these days use their own proprietary descriptions of skill level.

Here is my general description, intended to parallel or complement the PSIA levels 1-9. It describes terrain, conditions, and situations in which a skier is "comfortable and confident"--not just what the skier can get down. It describes "offensive" technique--using gliding turns to control line, and tactics (that is, line) to control speed, as opposed to relying on braking and skidding for speed control. Recognizing that "wedge" and "parallel" in contemporary skiing are not distinct techniques or turn options, it describes these characteristics as representative "milestones" of advancing skill involving the same fundamental technical principles. It suggests that "challenge" is not so much about what terrain you can survive, but about continuous improvement and how well you can ski any particular terrain, including easiest green groomed runs (see Level 9). Finally, it emphasizes technique as a means to an end--athleticism and skill, not "final form"--and values versatility, adaptability, and virtuosity over "perfection" of any single particular technique.

Skier Ability Level guide. (Click on the image for a larger version.)

flexion and extension movements, often necessarily vigorous, used to smooth out bumps and other terrain variations; the French term "avalement," meaning "to swallow," describes the large, active, intentional movements required to absorb large moguls

The flexiing and extending movements of absorption in large bumps involve both "up-down" and fore-aft movements, resulting in a motion of the feet relative to the body that resembles "backpedaling" on a bicycle.

The "backpedal motion" of absorption in real moguls; skier: competitor at Copper Mountain

a “downstem”—lateral displacement of the tail of the downhill ski; especially (but not necessarily) an unintentional downstem at the end of a turn in an attempt to set an edge

Abstem—note the outside (left) ski tail slipping out and away in frame 8, as a result of upper body rotation at the turn initiation.

Accelerated Frame of Reference
the skier’s point of view—the usual frame of reference when analyzing (or experiencing) ski technique, in which centrifugal and other inertial forces are “real” forces that the skier must act to balance against; compare with “inertial frame of reference”

a change in speed or direction of motion (a change in velocity); results when (and only when) an unbalanced external motive force applies to an object.

Unlike common usage, the strict physics definition of acceleration goes beyond just increasing speed to include any change in motion--including slowing down, or changing direction even with no change in speed. Any time a force acts unopposed (an "unbalanced force") on an object, the result will be the same thing: the object will accelerate. Whether it gains or loses speed or changes direction, or any combination, depends entirely on the direction of the force relative to the object's motion.


Acute Mountain Sickness
"AMS," or "altitude sickness," refers to a variety of symptoms and effects, ranging from mild to life-threatening, that can result from the thinner, drier air of high elevations above 6,000 feet (2,000 meters). Likelihood and severity of symptoms increase with increasing altitude.


For more information, refer to Dr. Dave Polaner's excellent EpicSki article, Altitude Adaptation and Acute Mountain Sickness

movement of leg or other body part TOWARD a center axis (“legs together”); opposite of "Abduction." (See illustration under "Abduction.")

AKA "jumps," aerials are skiing maneuvers performed in the air, typically involving "tricks" of some sort—spins, flips, grabs, and combinations, usually launched from a large bump, a cornice, or a purpose-built jump, usually (but not always!) intentionally.


Inverted Aerials. Olympic medalist (moguls) Bryon Wilson, World Moguls Champion Patrick Deneen, freestyle ace Sammy Carlson, Patrick Deneen



Upright aerials: Cossack Spread Eagle and MuleKick BackScratcher (Willi Furr), Daffy (PhilPug).

All images © Bob Barnes.



Anti-Friction Device—a part of modern ski bindings intended to reduce release-inhibiting friction under the boot toe from, especially, a forward twisting fall. It is often a small, slippery plate made of plastic or Teflon®-type material that the boot toe rests on, and some bindings incorporate a mechanical device of various sorts that moves with the boot.

An AFD on a Vist plate binding.



Affective Domain
Part of the CAP Model ("Cognitive-Affective-Psychomotor"), the affective domain of learning and development encompasses emotion, motivation, valuing, and commitment to learning. The CAP Model attempts to define hierarchical or sequential phases of development, from lowest to highest, in each domain. Maslow's Hierarchy of Needs represents one interpretation of the Affective Domain, specifically identifying a hierarchy of situational needs, with the suggestion that each higher level depends upon the levels below it being met or satisfied:

Maslow's Hierarchy of Motivational Needs

refers to positions of various body parts and how they move relative to each other when skiing; varies according to the specific mechanics of each turn; good alignment is essential for efficient and safe skiing.

"Alignment" also refers to the various concerns of specialized boot fitting and equipment setup intended to adapt unique individual body morphologies to the specific demands of skiing. Major issues include correcting for over-pronation and over-supination, addressing ankle function and range of motion, optimizing forward lean, and correcting for "under-edged" or "over-edged" conditions.



Acute Mountain Sickness (see), also commonly known as "altitude sickness."

Angular Momentum
property of a rotating object that describes its “quantity” of rotation; a function of its speed and direction of rotation, and the amount and distribution of its mass

Angular Motion
the motion of objects revolving or spinning about an axis

The spinning, twisting, and rotating movements of angular motion, as opposed to movement along a path from one place to another known as linear motion.


sideways bending movements of the ankles, knees, hips, or spine that allow control and adjustment of edge angle; see also "inclination" (leaning into the turn for balance) and "banking" (inclination without angulation).

Angulation; skiers: Annie Black (left) and "Tog"

countered, “wound-up” arrangement of the upper and lower body prior to a turn; creates tension in the muscles that, when released, helps initiate the turn

Anticipation-Release; skier: "Tog" at Arapahoe Basin

Applied Force
the push or pull that causes change in motion (acceleration); also known as “motive force” (compare with “inertial force”)



"Alpine Touring"—refers to specific equipment for, as well as the activity of, climbing uphill and skiing on skis with "AT bindings" that allow the boot heels to lift for easier hiking and then lock the heels down to enable skiing downhill with standard alpine technique.

ATS™ (American Teaching System™)
PSIA’s humanistic ski-teaching scheme that incorporates the Skills Concept™, a Teaching Model based on established educational principles, the Center Line™ Skiing Model, and a model for Guest Service

active absorption movements, as in “swallowing” moguls, involving deep flexing and extending movements of the entire body

Instructor Annie Black swallows a bump with "avalement." Notice her similar movements below in heavy, wind-blown crud at Snowmass (in green) and in Laure Pequegnot's winning World Cup slalom run at Copper Mountain:

inclination (tipping) of the entire body into a turn, with little or no angulation. Banking is not the same thing as "inclination," which refers to leaning (moving the center of mass) into a turn for balance. Inclination occurs in all turns that require balance—on skis, bicycles, or walking and running. Angulation refers to sideways (more or less) bending of the body, generally to adjust or control edge angle. Inclination and angulation are separate and independent—one a move of the center of mass, the other movements of body parts relative to each other—and good skiing demands management of both, independently. Banking is merely the special case of inclination without angulation.

Annie Black, showing that banking is not always an error!

Banking is sometimes considered an error, particularly when accompanied by rotation of the upper body. But many high-performance turns involve significant banking. When the inclination due to speed and turn radius provides sufficient edge angle on its own, very little angulation is needed to keep the skis holding and carving (see "critical edge angle").


Base of Support

Generally referring to the feet or supporting foot, "BoS" is the "balance point"—the point on which balance is focused—somewhere within the "polygon of sustentation" (see). When a skier is balanced on one foot, the BoS is a point along the edge of the supporting ski. When both skis support the skier, the BoS will be somewhere between the skis.


 The legend Jerry Berg, illustrating the relationship of the Center of Mass and the Base of Support.



Understanding the Base of Support is an important when discussing balance, which may be simply defined as the relationship between the skier's center of mass and the base of support.


Basic Parallel
a milestone of skill development and confidence in which the characteristics of the Basic Turn (“Q Turn”) include both skis remaining parallel and at similar edge angles throughout the turn; prior to Basic Parallel level, many basic turns will involve a wedge, at least at the initiation phase.

Basic Parallel Turn; click on image for larger version

tendency toward certain movement options, whether they are the most effective or functional for a given situation or not

Bilateral Transfer
the ability of one side of the body to more easily learn something already learned by the other side

the study of living bodies in motion, combining physics and anatomical function

planting the pole firmly to stabilize the upper body or produce rotational force (torque)

Blocking pole plants by master instructors Jerry Berg (left) and Eileen Brown

Blocking pole plant produces torque the way a wrench turns a nut. Snow pushes against the pole, which transmits the force through a "lever arm" (your arm), creating a twisting force on your body and skis.

Bloom’s Taxonomy of the Cognitive Domain
a descriptive hierarchy of levels of understanding and the development of higher-order thinking skills, from simplest to most complex (knowledge—comprehension—application—analysis—synthesis—evaluation); describes not how much you know, but how deeply you understand something.

Benjamin Bloom's "Taxonomy of the Cognitive Domain" illustrates increasing sophistication in the development of understanding, beginning with simple "knowledge" as the lowest rung on the ladder.

With the Affective Domain and the Psychomotor Domain, the Cognitive Domain forms one third of the "CAP Model" of learning and development.


"Base of Support" (see)

scrubbing off speed using the ski edges as scrapers; occurs whenever the skier intentionally pushes or twists the ski tails toward the outside of a turn, into a skid. Braking is one of two fundamental ways to slow down: the other involves tactics: ie. going uphill.

simultaneous (but independent) rotation of both legs, using the “fulcrum mechanism” (independent leg rotation)


Breakable Crust
One of skiing's most challenging conditions, breakable crust, like it sounds, describes soft snow beneath a fragile, thin surface layer of harder, windblown or icy snow. What makes this condition so difficult to ski is that the crust layer is inconsistent—like an egg shell, or thin ice on a pond, it is solid until it suddenly breaks away, unpredictably. Skis glide or skid over it, then suddenly, with a little more pressure and no warning, break through to the soft snow beneath, where they get "stuck" under the crust and refuse to turn. Balancing and turning in inconsistent breakable crust challenges even the most determined expert. 


Tactics for breakable crust include keeping skis fairly close together and standing on them both, as a platform, so that one does not break through the crust while the other stays on top. Vigorous "up-down" movements and constant activity are the key. Keep moving, keep turning—don't freeze up or hesitate, or the snow will knock you down. It often helps to hop right out of the snow, turn the skis, and then slam them back down with enough force to break through the crust reliably. Don't try to turn or twist your skis when they're in the snow—let them slice and bend and carve, and then pivot them as much as needed only when they're in the air again. Conversely, sometimes the best strategy is ski "light" and soft, avoiding or minimizing changes in pressure and trying to keep the skis on top of the crust. But in general, just remember that in breakable crust, all of the rules of skiing crud apply, including my golden rule that "if you want to get a good taste of crud, ... you've got to eat some." Like all challenging conditions, breakable crust is an acquired taste, and a true test of athleticism, skill, balance, touch, power, purpose, and will. Remember that there are no bad conditions. Conditions are either good . . . or good for you!

Bob Barnes skis breakable wind-blown crust at Loveland Basin, Colorado, with vigorous up and down movements and constant rhythm. Keep turning!




See Moguls.


built-in curve of ski bases, designed to distribute pressure along the length of the skis and to store energy when bent into reverse camber

Modern skis come with many varieties of camber, from traditional high camber (A), to contemporary lower camber (B), full reverse camber (C), primarily intended for deep powder, and hybrid camber (D) meant to float and steer easily in powder like a reverse camber ski, while carving and turning on firmer snow with some of the performance and feel of a traditional full-camber ski.


Traditional camber (A) distributes centered pressure along the length of the ski, allowing the entire edge to grip and carve when tipped on edge. Reverse camber (B) focuses pressure under the foot on firm snow, but allows the ski to slice and carve easily through powder, while keeping the tip and tail near the surface, "lighter" and easier to pivot and twist.  Combined with increased width for added flotation, reverse camber or "early rise" fat skis can make deep powder skiing much easier for skiers without the expertise and finesse to slice and carve traditional skis through the deep. For experts, they add new options and opportunities in powder for moves not possible on traditional skis, even though many experts still prefer the sensations they get from narrower traditional cambered skis bending and loading and unloading like springs as they slice and porpoise deep beneath the powder surface. Certainly, the "rules" of camber have changed, and new options and experimental shapes continue to emerge.



to correct for anatomical misalignment–under-edged or over-edged–by attaching wedges or grinding boot soles at an angle.

CAP Model—Cognition, Affection, Psychomotor
Conceived and published in the 1950's by a team under the leadership of Dr. Benjamin Bloom, the "CAP Model" identifies three critical categories ("domains") of human development and education. The Cognitive Domain encompasses understanding and knowledge and the development of logic and higher-order thinking skills. The Affective Domain deals with emotion and motivation, with developing commitment and value systems. The Psychomotor Domain includes physical and athletic ability, coordination, and the development of purpose-driven athletic skills.

Bloom's team, and subsequently others, attempted to define sequential or hierarchical "taxonomies"—increasingly complex and sophisticated stages of development—within each domain. Bloom's original and well-known taxonomy addressed the Cognitive Domain (see "Bloom's Taxonomy of the Cognitive Domain"). Various others have categorized the Affective and Psychomotor domains. The following graphic summarizes some of the better-known classifications.

The three categories of development and education defined in Bloom's "CAP Model"—Cognitive, Affective, and Psychomotor. Within each domain, the Model defines essentially sequential stages of learning and development from simplest to more complex and higher-order levels. I have listed here "Maslow's Hierarchy of Needs" to define the Affective Domain, acknowledging that other classifications relating to increasing levels of commitment to and valuing of a skill or concept are also common.

In education, the CAP Model serves well as a guide or reminder that there is more to learning and teaching than just "knowledge transfer" or memorizing facts—or in athletics, than just "motor skill development." Effective teachers, instructors, and coaches nurture development in all three domains, and recognize the interactions, opportunities, and limitations that each domain incorporates.

Critical when teaching children, the CAP Model provides a backbone for understanding the typical developmental stages human beings pass through from birth through full development of adult-level capabilities within each domain. Physical development (motor skills, as well as muscular and skeletal development), mental, logical, and critical thinking ability, as well as motivational, emotional, moral, and social development, play vital roles in determining what students are capable of, as well as determining most effective methods for teaching and motivating at various ages and stages of development.

The CAP Model, along with its various components, is not without its critics and controversy, regarding both its content and its most effective application. There is plenty to argue about regarding the sequencing or descriptions of the various stages within each domain, as well as whether, or to what extent, the classifications represent inevitable sequential stages at all. Clearly, the three domains cross over, overlap, and interact with other, so we must not look at them as completely independent, isolated entities. Cognitive skills influence learning physical skills, as do motivation, commitment, and will (affective domain).

smooth, tough, slippery, rubbery tissue that lines joints

turning with little to no lateral slippage or skidding of the skis; to carve, skis must be tipped on edge and bent into “reverse camber,” forming an arc shape that defines the radius of the turn, as the skis slice forward through the snow

Center of Mass
Commonly abbreviated "CM" (or "CG" for center of gravity), this is the point at which all the mass of an object or system of objects acts as if it were concentrated, and around which an object spinning freely through space will rotate. For all practical (skiing) purposes, the term is equivalent to and interchangeable with "center of gravity."

Center of mass

A very important (and commonly misunderstood) point about center of mass: it is "mobile"—it is not located in a particular part of the body like an organ. It moves within—and sometimes outside of—the body with changes of body position. In particular, it is not the same as, or necessarily in the same place as, the hips.

CM moves about with varying body positions—it is a dangerous oversimplification to equate it with "hips."

Misunderstanding of center of mass commonly causes critical errors in movement analysis—particularly when assessing balance and stance issues and fore-aft pressure. Instructors—be sure you've got this right!

Center Line™ Model
PSIA’s skiing model, based on the earlier Skills ConceptTM and conceived in the late 1980's, which categorizes all possible skiing movements and intents and identifies sound, efficient fundamentals common to good skiing at any level of skill. It encompasses both linear learning (increasing skill level at the same thing) and lateral learning (learning different things, exploring different skill blends and intents for varying purposes, conditions, and desires).


  My conception of PSIA's Center LineTM Model, based on the Skills ConceptTM, showing all possible movement blends and "skill biases," with the basic turning skill blend in the center. A good skier learns to master the entire spectrum, purposefully applying varying movement patterns according to need, intent, and desire. 



As originally conceived, the Center Line Model graphically represents all skill blends and intents ranging from pivoting and braking (which it called "rotary biased") to pure carved arcs ("edge-pressure biased"). Within the Model, the Center Line itself represents the skill blend of offensive turning for direction control, involving a blend of rotary, edging, and pressure control movements as needed to control turn size and shape.


Center Line™ Milestones
Wedge Turn, Wedge Christie, Basic Parallel, Dynamic Parallel—skiing maneuvers that demonstrate the same essential fundamentals at increasing levels of skill. Never intended as steps in a teaching progression, or "final forms," the "milestones" simply represent ideal, "default" principles and intent of efficient, offensive ski turns, differing only in characteristics based on speed and skill level.


While the whole of ski technique reflects a spectrum of intents from quick, harsh braking (speed control) to the joy ride of "pure carved arcs," the Center Line itself, and the Center Line Milestones derived from it, represent only the technique of pure, offensive turns intended to control direction—to go precisely (and efficiently) where you want to go. They are smooth, linked (without traverses), rounded turns in which the skis glide the direction they're pointed, with as little skidding as possible (given skill level, equipment choice, and turn radius). While skiers may, of course, make turns of any size (radius), instructor demonstrations of the Center Line Milestones generally require turns smaller than their skis can "pure carve," in order to represent a blend of the basic skills of pressure control, edging, and rotary. The over-riding "master" technical principle of this turn—again, at any level of skill—is what I call the principle of "positive movements"—all movements, including rotary, edging, and pressure control movements, tend in the direction of the turn. To go right, nothing goes (intentionally) left. Even at the Wedge Turn level, there is no intentional skidding, twisting, pivoting, or pushing of the tails toward the outside of the turn, and both skis tip and turn simultaneously in the direction the skier intends to go.


From wedge turns to dynamic parallel turns, the Milestones all demonstrate this very same turn, with the same fundamental movement patterns, as those movement patterns develop from "embryonic" first turns through the offensive, high-speed dynamic turns of World Cup racers. Because they all arise from the same intent—to control direction precisely and efficiently—they serve as reliable indicators of progress on the road from beginner to expert. 


Note that this technical model does not recognize "parallel" as a fundamental principle of good turns, but merely as a characteristic of those principles as skill and speed increase. According to the Center Line Model, we do not teach wedge turns—or parallel turns. We teach the movements and intents of expert turns, even to beginners, recognizing that at lower levels of skill and speed it is difficult to turn both skis at the exact same rate, resulting in "first turns" typically involving a wedge. The wedge of "Center Line" Wedge Turns is specifically not a braking or defensive (speed control) move. It is not intentional (other than in an instructor's demonstration), and it is certainly not "important" or fundamental to those first turns. It is merely a minor characteristic of lower skill level and speed. 


On the other hand, when the intent becomes defensive, any skier from beginner to expert will make fundamentally different movements from those of the Center Line Milestones. Intent dictates technique, and the intent to brake elicits negative movements that twist the tails into an intentional skid—including both parallel skids and braking wedges. Braking is certainly an important ability in good skiing, but it is not at all what the Center line Milestones serve to demonstrate.


The original concept of the Center LineTM Model defined six milestones: Wedge Turns, Wedge Christie 1, Wedge Christie 2, Open Stance Parallel, Dynamic Parallel, and Diverging Parallel. Later versions simplified it to the current four—eliminating the distinction between wedge christie 1 (matching after the fall line) and 2 (smaller wedge, with matching before the fall line), renaming "open stance parallel" to "basic parallel," and eliminating the confusing "diverging parallel" (which recognized the very active inside leg and occasional divergence in very dynamic skiing). 


See also positive movements, negative movements, and "Q" (quintessential) Turn, as well as entries for each individual Milestone (Wedge Turn, Wedge Christie, Basic Parallel, Dynamic Parallel).

Centrifugal Force
Meaning “center-fleeing,” this is an inertial force (not an "applied force") felt as a pull to the outside of a turn, against which a skier must balance.




Centripetal and centrifugal forces: the force of the bowl on the ball, causing the ball to move in a circle, is centripetal force; the force of the ball, pushing outward on the bowl as a result of its circular motion, is centrifugal force.

Many are the confusions and myths about centrifugal force. A full understanding of it requires more than just a fundamental grasp of basic physics, including an understanding of frames of reference and the relativity of motion. However you may choose to look at them, remember that, from the neck down, our bodies have been learning to deal with these effects and concepts since birth. Don't overthink it!


 For anyone who wishes to argue that centrifugal force does not exist, I offer this little illustration. (Yes, I know that you can explain the phenomenon differently from a different frame of reference, but it is still a real, measurable phenomenon, and it has a name: centrifugal force. And don't forget that, if you want to play that game, I can just as easily define a frame of reference in which centripetal force does not exist. Get over it!) I wish I knew who created this great little cartoon, but I don't. If anyone knows, please send me a note so I can attribute it properly. If you are the creator, and you'd prefer that I remove your cartoon from this Glossary, please let me know.



Centripetal Force

Meaning “center-seeking,” this is the generic name for any applied force that causes an object to move in a circular arc (to turn). In skiing, it includes gravity, ski-snow and pole-snow interaction, and wind.

edges rapidly grabbing and releasing in a turn, usually resulting from over-edging or edges that are too sharp

brief braking action, usually done prior to a turn to create a platform and rebound

generic name for a turn or part of a turn where both skis are on the same (right or left) edges


Closed Gate
double-pole race gate set vertically on the hill (one pole set directly uphill from the other) 


pulling the skis together to make them parallel, as in a stem christie; (compare with “matching,” as in a wedge christie)

 "Closing" means bringing skis from a wedge to parallel by pulling the tails together, in contrast to "matching," which is a hallmark of contemporary early turns as the tips of both skis are steered continuously into the turn with "positive movements."


CM (or CoM)
Common abbreviations for center of mass (see).


“knowing”— the ability to comprehend and understand at many levels

Command Teaching Style
teaching strategy where the instructor maintains tightest control, giving specific instructions and direct, immediate feedback

"Common Threads"
fundamental elements of good skiing that remain the same at any skill level along the Center Line™

Complete Turn
turn that crosses the fall line and continues far enough around that speed control from braking isnot necessary

Conscious Competence (learning model)

a four-stage (with arguably a fifth stage) model describing typical stages of learning, particularly relevant to physical skills and athletic performance; the stages are

  1. Unconscious Incompetence—don't know what you don't know--as they say back home in Maine, he is "so numb he don't even suspect nuthin'." Ignorance is bliss?
  2. Conscious Incompetence—the beginning of awareness that there is something you don't know, or cannot do, and that it is worth learning. You aren't good at it, but at least you know that you aren't good at it.
  3. Conscious Competence—Knowledge and/or skill is developing; at this stage, you understand and can perform the task with skill, but only while focusing consciously on it; movement patterns are not yet automatic/autonomous.
  4. Unconscious Competence—it is now "second nature," and you can perform it without much, or any, conscious thought; you can do it while focusing on other things; the physical skills are "second nature," and you can think about tactics, outcomes, and so on.

Many (most?) top-performing athletes perform at the "unconscious competence" level, in which they can focus on outcomes, rather than processes, on what to do, not how to do it—on tactics and intent, with confidence that your body has the skills to take it from there. Interestingly, though, since the actual movements and skills take place in the background, mostly without conscious awareness, at this level, great athletes often have difficulty explaining or describing—or teaching—what they do, and may also struggle with identifying the problem and effective self-coaching when their performance declines. Some natural athletes may have never passed through a "conscious competence" phase, while others may have performed and evolved at the "unconscious competence" level for so long that they have lost touch with or forgotten (consciously) the nuts and bolts and fundamentals of what they do so well.

I believe, and others have postulated as well, that there is a fifth level in this model, that becomes important for teaching and coaching at the highest levels. A return to "conscious competence" takes place as athletes develop, or redevelop, awareness and understanding not only of what they do, but of how to teach and coach those fundamentals to others, as well as how to channel this awareness such that it does not interfere with their own ability to perform at the "unconscious competence" level when needed. Some teachers and coaches can be reasonably effective at the "conscious competence" level, without ever advancing to the next level—obeying the old adage that "those who can't, teach." But the most effective teachers demonstrate the ability to perform at a very high (unconscious competent) level with the awareness and understanding needed to break performance down to its fundamentals, to coach those fundamentals at any level, and to modify—consciously—their performance for demonstrating both ideal and less-ideal movement patterns, as needed.

Conservation of Momentum, Law of
physical law that states that the total motion of a group of objects cannot change unless a force from outside the system acts on it. The Law of Conservation of Momentum explains the rotary mechanism known as “rotation,” in which momentum (angular, or "rotational" momentum) of the upper body is transferred to the lower body and skis when the skier slows or stops the upper body's rotation. 

Converging Step
turn initiation involving lifting and displacing the new outside ski into a “tails out, tips together” arrangement with the other ski




Smooth, easy-to-ski snow condition created by modern grooming equipment ("Snow Cats"); corduroy snow has a fine "ribbed" texture reminiscent of corduroy fabric.






an overhanging shelf of wind-deposited snow on the lee (downwind) side of a ridge, cliff, or other obstacle. Ranging from just a foot or two to many feet high, cornices can be fun to launch from with a little "mandatory air." But they can be dangerous, too, as they can give way without notice, often causing an avalanche. When hiking along a ridge, it's usually wise to avoid approaching the lee edge too closely, as the solid-feeling snow may be a fragile cornice just waiting to fracture.









Rotary mechanism involving simultaneous twisting of the upper and lower body in opposite directions, based on Newton’s law of “equal and opposite reactions”



Critical Edge Angle
Related to "Platform Angle" (both terms coined by Ron LeMaster), this concept describes the edge angle of the ski not in terms of its relation to the slope, but relative to the force the skier applies to it. Critical edge angle denotes the minimum platform angle that enables a ski to hold—or the angle at which the ski releases its edge grip and allows the ski to slip downhill. While edge angle relative to the slope, combined with sidecut and appropriate pressure to bend the ski, determines the radius of the bent ski's arc and, therefore, its "turning radius," Platform Angle determines whether or not the ski will hold or slip sideways. Essentially, a ski tipped to a 90 degree angle or less (an acute angle) to the force applied to it (a line from the Center of Mass to the ski's edge) will tend to grip; when tipped to greater than 90 degrees, it will release and slip. A platform angle of 90 degrees to the applied force, then, is "Critical Edge Angle"--the minimum angle for a ski to hold. Note that this angle is independent of the angle of the ski to the snow surface, which depends on the skier's inclination angle and the angle of the slope, as well as the skier's angulation. Platform angle depends only on the degree of angulation.

Platform Angle turns.jpg

See also Platform Angle, and for a more detailed look and discussion of these edging concepts, see posts #17 and #18 in the thread, "What is the best edge angle for max grip?"

moment when linking turns in which the center of mass moves from one side to the other, relative to the skis

any of a variety of moderately-to-extremely challenging, inconsistent, heavier snow conditions; dense, chopped-up heavy snow, wind-affected powder and slab, avalanche debris, freeze-thaw-cycled snow, breakable crust, moist "sierra cement," "boilerplate," and "frozen chickenheads" are among the colorful euphemisms that describe common types of crud. While crud is challenging, I maintain that "there are only two kinds of snow conditions: conditions that are good, and conditions that are good for you!"

See related EpicSki Article about crud skiing here.

to reverse the natural bend of skis by controlling edge angle and pressure, allowing the skis to carve a turn

Ski decambering when tipped on edge and pressured in the "sweet spot"

direction change (turn) caused by the snow pushing on the skis

Delta Angle
The difference in height from the base of the ski between the toe of the boot and the heel, determined by the difference in height between the binding toe and heel pieces, and adjustable by adding shims or ramps between the ski and binding, by adding various thickness plates to the heel and toe of the boot sole, or temporarily by inserting tape or shims between boots and bindings. Delta angle influences the critical forward lean of the lower leg, which is an essential component of equipment setup and athletic "ready" stance. Not to be confused with Ramp Angle (see), which refers to the angle of the footbed inside the boot.


See also "forward lean."


Delta Angle of bindings, or under-binding or boot sole shims (exaggerated in this illustration), tips the entire boot, as well as the lower leg, forward or back, without affecting ankle flex angle. Compare with Zeppa angle (ramp angle) inside the boot, which affects ankle dorsiflexion angle, but does not directly affect shin forward lean.


"Downhill"—the fastest of the four classic alpine racing disciplines of Slalom, Giant Slalom, Super-G, and Downhill. Downhill races involve the fewest and longest turns, and at the highest World Cup levels may reach speeds of as much as 100 mph (typical speeds are 60-80 mph, or 100-130 km/hr). 



"Deutsches Institut für Normung" (German Institute for Standarization)—internationally recognized institute in Germany that develops and defines standards for everything from paper sizes to ski binding and boot sole specifications. In skiing, "DIN Standard" typically refers to the design of the components of the binding and the ski boot sole that interface with each other to optimize both retention and release. DIN Standards define the materials and shapes of the components, as well as the numerical scales (and related forces) used for binding release settings based on skier size, weight, and skiing type. A "non-DIN boot" or "non-DIN binding" may be one manufactured prior to current standards, or one worn to the point that it no longer conforms to current specifications. Bindings must be designed and built to current specifications, and also tested periodically to ensure that they function properly, according to the standard. Boots or bindings that do not conform to current DIN Standards are sometimes referred to as "non-indemnified" and typically cannot be sold or adjusted by most ski shops, for liability and insurance reasons.


Stands for "Duration, Intensity, Rate, and Timing."


When describing movements or techniques, these characteristics are critical for painting the full, accurate picture. Duration—how long does the movement last? Intensity—how powerful or weak, vigorous or casual, muscular or passive, explosive or subtle, is the movement? Rate—is it continuous, or does it increase or accelerate in intensity? Is it smooth, or jerky? Timing—when does it occur? Which part of the turn? When does it begin and end?


Distributed Practice
brief, focused, intermittently-repeated training sessions, which usually produce more learning than single, long sessions ("massed practice"), especially when anchoring and reinforcing previously learned movements.

Diverging Step
turn initiation involving lifting and displacing the new outside ski into a “tails together, tips apart” relation with the other ski—like skating



Commonly held--often even by a majority--but unsupported beliefs, masquerading as facts. Like many sports and endeavors, skiing is full of dogma. Some is ancient wisdom that may have been true at one point in time but that has become obsolete. Some was never true. Some of it stands the test of proof, but much of it fails when put to that test. Question and challenge everything! Maintain "scientific skepticism" about all things and seek to understand, rather than just to absorb "knowledge" (which can be right or wrong). 

motion of the ankle bringing the toes “up” toward the shin; opposite of plantar flexion

brushing out of the tail of the downhill ski, to check speed and/or create a platform for a pushoff or rebound turn initiation

Dynamic Fall Line
the path a rolling ball would follow down the ski slope from a given point--a function of the angle of the hill at any point and the momentum of the ball. Often confused with the "actual" fall line, which is simply "straight downhill" from a given point, the terms describe different things. Clearly, if you were to roll a ball across the slope, it would not roll in the direction of the fall line at first--by definition--but it would "seek" the fall line as it arcs down the hill. As it continues down the hill, it may actually go uphill at times--opposite the direction of the fall line--as it rolls up and over moguls and small hills and gulleys. 

Dynamic Parallel
highly carved, high-performance turn representing the top skill level milestone of the Center Line™ Model (the quintessential "Q-Turn" representing the fundamental principles of smooth, efficient, linked, offensive direction changes at a high level of skill and moderate or higher speed)

DP 07 numbered.jpg
Dynamic Parallel Turns; click on image for larger version

the fundamental skill group encompassing movements that control the angle of the ski bases to the hill, as well as the angle of the ski bases to the force the skier applies to them (see Critical Edge Angle).

Edge angle relative to the slope follows a simple formula: Edge Angle = Inclination Angle + Angulation Angle + Slope Angle. In the top half of a turn, slope angle is negative and reduces edge angle; as the turn progresses, slope angle progressively increases edge angle.

Effect of edge angle (relative to the snow) on turn radius in a carved turn on hard snow, according to the formula turn radius = sidecut radius X cosine of edge angle

EpicSki Academy

"ESA" is a premium independent ski camp for serious adult students of intermediate-to-expert ability. Originating in 2003 through the inspiration and design of the members of the EpicSki.com community, EpicSki Academy features some of the top American ski instructors and coaches from across the country converging with motivated students at premiere hosting resorts including Alta, Snowbird, and Brighton in Utah, Stowe, Vermont, Aspen-Snowmass and Arapahoe Basin in Colorado, Big Sky-Moonlight Basin, Montana, and the Lake Tahoe region of California.





Since the acquisition of EpicSki.com by Vail Resorts, EpicSki Academy is currently on hold, pending (perhaps) a program re-design suitable to the current owners. 


a movement of the foot and ankle describing tipping the sole of the foot outward, as opposed to inversion, which describes tipping the sole inward.


 Eversion and Inversion of the foot and ankle


straightening or reducing the angle of one or more joints

External Rotation
describes the turning activity of the inside leg of a turn; turning the leg or foot “toes out”

Fall Line
“straight downhill” from any given point on the slope. A common misconception is that the fall line is the path a ball would take as it rolls down the hill. Consider that if, for example, you were to roll a ball down the side of a half pipe--when it reached the other side, it would actually go uphill for a bit--hardly following the fall line. A ball rolling down a mountain will glide up and over moguls, banking turns on the sides of gulleys, and so on. The path of the ball is sometimes called the "Dynamic Fall Line" (see above) and it is the same as the actual fall line only at the moment the ball is released from a stop (except on a perfectly flat, tilted plane with an unchanging fall line). At all other times, the ball's path is influenced by the fall line, but also by its own momentum.

Fan Progression
any series of exercises done from increasingly steep traverses, with complete turns the intended final outcome. Fan progressions are great for developing confidence with a new movement, without first committing to complete turns with their often frightening initial "release and dive" down the hill.



response to an action that affects the action or subsequent action; an essential component of practice, without it no learning can take place


"Federation Internationale de Ski" (International Ski Federation)—the highest international governing body for ski and snowboard competition, including Nordic, Alpine, and Freestyle skiing and snowboarding. Formed in 1924 and headquartered in Switzerland, the FIS establishes the rules and maintains the records of the various sports and disciplines under its jurisdiction.


bending in one or more joints, such that the body parts affected by the joint move closer together; the opposite of "extension."

vertical gate combination consisting of three or more race gates set directly down the fall line


3-gate flush, showing two possible routes through the combination.


Forces in Turns
This diagram illustrates the two main forces a skier feels in a turn—the pull of a component of gravity constantly down the hill (white arrows, or "vectors") and the pull to the side (away from the center) known as "centrifugal force" as a result of the turn (red vectors), which increases with speed and with tightening of the turn radius. These two forces combine either to pull the skier into the turn or out of the turn, as shown by the large blue vectors, depending on the speed, steepness of the hill, and radius of the turn. These unbreakable laws of physics dictate where in the turn we can create the pressure needed to bend a ski and carve—as indicated by the portions of the two example turns in which the dotted blue line lies outside the gray path of the skier's body (center of mass).



Few things in the dogma of ski technique bring more confusion than the seemingly simple directive to "get forward" or to "keep forward." The importance of being forward, moving forward, and keeping out of the dreaded "back seat" tops the list of unquestioned and unquestionable doctrine, incontrovertible, nearly sacred tenets of skiing truth. So let's question it a little!


First of all, "move forward" sounds about as simple and clear as it could be, doesn't it? But even if we were to agree on the dogmatic need to "move forward" at the start of a turn (more on this later), the simple directive is far from clear. I can think of a number of directions that could easily qualify as "forward," and they are not at all the same: the direction the skis point, the direction the skis are moving (which may or may not be the same as the direction they point), the direction the body faces, or the head or eyes face, the direction the body is going, down the hill, toward the "apex" of the next turn, and so on—any of these and more could fit the description of "forward." And then we can add the dimension of time: is it "forward" now that matters, or at some point later in the turn? Finally, forward of what? Motion is relative, so the body could move forward relative to the feet, or relative to the ground, or relative to any number of other reference points, both moving and still. 


For the sake of brevity, I'm going to cut to the chase here in this Glossary. The shaping phase of a turn is that portion during which the snow, through the skis, pushes against the body (center of mass), causing a direction change (turn). When something pushes against something else, the thing being pushed must, obviously, be "ahead of" (forward of) the thing pushing. And "ahead of" clearly means here, "in the direction of the push." The unicycle is an illustrative example—whichever direction the unicyclist wants to go, he must first move his body in that direction, relative to the point of contact of the wheel on the ground (or move the wheel in the opposite direction, relative to the body), before providing the pedal power that allows the wheel (actually, the ground) to "push" the body in the desired direction. And before he can go another direction, he must first rearrange his body "ahead of" his wheel again, in the new direction. To the unicyclist, then, "forward" always means "in the direction he wants to go (to accelerate, if you must get technical)," relative to his wheel's point of contact with the ground. Skiing is essentially the same.


"Forward," on skis, therefore, means "in the direction the skis are pushing, or are about to be pushing," relative to the feet or "balance point" (point of contact). This direction changes throughout the shaping phase of a turn, but is roughly perpendicular to the arc of the skis, at the point of contact at any moment, toward the inside of the turn. And it is only necessary to be "forward" during the shaping phase. During the transition—between shaping phases—we must move our body, relative to our (moving) feet, to the position that will provide perfect balance (that is to say, "forward of the feet" in the direction they're about to get pushed) when the shaping phase begins.


I'll add to this definition when time allows, but for now, again, "forward" means "in the direction the feet are getting pushed by the snow," and it is only necessary to be "forward" during the part of the turn when the feet actually are getting pushed by the snow—the "shaping phase." 


Remaining questions to explore include when do we need to move "forward," how much do we need to move, and how do we accomplish it? Accurate, timely movement of the feet and body, relative to each other, provides optimal balance in the shaping phase. It also allows further fore-aft adjustment along the length of the ski(s), enabling us to move pressure forward or back of "center" for purpose, affecting the way the skis perform on the snow; to what extent, and when, then, do we need to make such adjustments?


Many energetic discussions of this topic have occupied the EpicSki community over the years. Here's a recent one, from the 2014-15 season: Instructors: do you teach moving forward at initiation? If so, how? Or why not?. My post #6 in this thread includes links to many more good discussion threads.


Forward Lean

Forward lean generally refers to the angle of the lower legs when the shins are neutral in the boot cuffs, a function of boot design and setup and individual lower leg shape and size. It is a critical adjustment, especially with snug-fitting, stiff high-performance boots that greatly restrict ankle movement and therefore must "set" the shins at an optimal angle to maximize stance efficiency and range of flexion and extension. Adjustments that affect forward lean include tilting the boot cuffs more forward or more upright, adding or removing shims between the boot shell and the back of the inner boot, and tilting the entire boot forward or back by adjusting delta angle. "Ramp angle" (zeppa angle) and heel lifts inside the boot do not directly affect forward lean, although by raising the calf higher out of the boot cuff, or by "opening" the ankle (reducing dorsiflexion and allowing the ankles to flex more) they can sometimes have an indirect effect. Due to the complexity of the various factors, this critical adjustment is usually best left to a highly competent master boot fitter.


Optimal forward lean is one of the most critical considerations in equipment choice and setup, especially with stiff, snug, high-perforance boots that greatly restrict ankle movement. As the following illustration shows, it influences basic, athletic stance and fore-aft balance, and optimizes the functional range of flexion and extension that is so critical for skiing moguls and for any highly dynamic skiing.


Forward lean (lower leg angle) dramatically affects fundamental stance and range of flexion-extension. Skiers on the left in all three rows are all in identical fore-aft balance, as shown by the dotted vertical line through their centers of mass and their boot centers. But only skier A1, with optiimal forward lean, stands in a natural, highly functional stance. Skiers B1 and C1 must resort to contrived and dysfunctional stances to achieve fore-aft balance. With ankle movement largely restricted in modern ski boots, other joints (knees, hips, spine, arms) must combine to maintain fore-aft balance. When one or more of these joints reaches the end its range, the skier's continued flexion or extension will compromise fore-aft balance. As the center and right columns show, only skier A can maintain fore-aft balance throughout the range from full extension to deep flexion. 


Factors that influence forward lean either directly or indirectly include boot design, delta angleramp angle (zeppa angle), boot cuff alignment or shimming between boot shell and liner behind the calf, and individual leg and calf morphology and ankle function.


This image shows how the shape and thickness of the calf affects forward lean (A—"normal" calf, B—lower, muscular calf increases forward lean). Figure C shows a shim placed between the shell and the back of the cuff increasing forward lean in the same way, similar to tilting the whole boot cuff forward. Both of these factors increase dorsiflexion (ankle flex) as well as forward shin angle, and may be problematic for skiers with limited ankle motion range.


Delta angle, resulting from binding design or shims beneath bindings or variable-thickness plates attached to boot heel and toe, tilts the entire boot forward or back, affecting forward lean without affecting ankle dorsiflexion.


Zeppa angle, aka ramp angle, affects ankle dorsiflexion without directly affecting forward lean of the lower legs.


See also Delta Angle and Ramp Angle/Zeppa Angle.



Fulcrum Mechanism
independent steering of the legs beneath the pelvis, with no involvement of the upper body; highly versatile, it is the essential rotary principle of modern “Center Line™” turns. Today more commonly referred to as "leg steering," "leg rotation," or "independent leg rotation," the fulcrum mechanism entails each leg rotating about a separate axis, turning in the hip socket, beneath a stable pelvis and upper body. Each leg, planted on the ground, stabilizes the pelvis and provides the resistance against which the other leg turns. The fulcrum mechanism is easily visualized and experienced by standing on two separate barstools (not recommended if the bartender is watching) and turning each stool with a foot. Highly versatile, with the fulcrum mechanism we can turn either ski or both skis simultaneously and with great precision. When both legs rotate simultaneously and at the same rate and intensity, keeping the skis parallel, the fulcrum mechanism is traditionally known as "braquage."

AKA "Independent Leg Rotation," the Fulcrum Mechanism describes the legs turning independently in the hip sockets beneath a stable pelvis and upper body, each leg rotating against the resistance of the other. It requires two separate pivot points with some separation between the feet, and (for both feet to turn) some pressure on each foot.

any exercise done from a traverse, with repeated moves or turns downhill, then back uphill, and no “complete” turns; tracks resemble a garland strung on a Christmas tree.




Gates are the obstacles racers must turn around in a race. They can be simple single poles, or a pair of poles supporting a cloth panel between them. FIS-sanctioned races involve double pole gates, involving two separate gates (single poles or panels) separated by several meters, forming an actual gateway through which the skier must pass, in either direction. Traditionally made of bamboo, modern gates are usually plastic, with hinges at the bottom allowing them to bend over without pulling out of the snow when a skier hits them. Gates used for training can also include very short "stubbies," plastic brushes, traffic cones, or any other object placed on the snow--even shadows of lift chairs can serve as useful and fun training "gates." 


Gates can be set in many ways, and in various combinations--see illustration. Double pole gates can be "open"--set across the hill, or "closed," set one pole above the other, or "oblique"--set at an angle. "Offset gates" require the skier to travel some distance across the hill between gates, while "vertical combinations," including flushes and hairpins, involve require minimal-to-no travel across the hill. 


Giant Slalom

"GS." With "Slalom" (SL), Super Giant Slalom (Super-G, or SG), and "Downhill" (DH), Giant Slalom is one of the four disciplines of traditional alpine racing. GS and Slalom are often referred to as the "technical disciplines," where technical turning ability plays a larger role, vs. the "speed events" of Super-G and Downhill, where gliding ability and fearlessness at speed may trump the technically "perfect turn." Giant Slalom is somewhat faster than Slalom, with gates spaced farther apart down the hill and turns averaging approximately 2.5 seconds.

Olympic Gold medalist and World Cup Champion, Anna Fennninger of Austria, training Giant Slalom at Aspen Highlands, Colorado.


GO! Factor
key ingredient of the offensive state of mind of the expert skier, in which turns are made to control direction, not speed, to “go that way,” not to “stop going this way.” With the GO! Factor, experts glide and control line, using tactics, not technique, to manage speed, while most skiers only brake. Experts do not turn to control speed—experts turn so they don’t have to control speed!


The vast majority of recreational skiers, at all ability levels, tend to focus directly on speed control rather than direction control (where speed control becomes an indirect effect of the chosen line and tactics—"skiing the slow line fast"). Their skiing lacks the GO! Factor, and learning to acquire this habit becomes the single most critical and effective link to the elusive world of expert skiing. Lacking the GO! Factor is the root of perpetual mediocrity—regardless of technical skill level—and the primary cause of the dreaded "intermediate rut." For anyone aspiring to break through to the gliding effortlessness and control of experts, the first step—again, at any skill level—is to find your GO! Factor! To ski like an expert, begin by thinking like an expert. Experts don't just do what they do better than the rest of skiers. Most of the time, they are doing something entirely different from other skiers. They focus on GO. Do it!



Giant Slalom (see).

Guided Discovery Teaching Style
teaching style in which the instructor leads students to a "self-discovery" of a particular desired outcome or answer through carefully chosen questions and exercises, without ever simply “telling” the answer


H Gate (Seelos Gate)

a combination of race gates with a vertical or "closed" gate (two poles set one directly above the other, that the racer must pass between) between two open gates (poles set horizontally across the hill); viewed from above, it resembles the letter "H" turned on its side.


An H-gate sequence, showing two possible routes through the vertical "closed" gate in the middle.


Habitual Skills
movement patterns performed “automatically” from muscle memory

vertical gate combination consisting of two closed gates set in the fall line

upright aerial maneuver involving one complete spin, also known as a "360."


PhilPug throws a helicopter at Arapahoe Basin.


A 360 (helicopter) from below. Skier: Willi Furr



PSIA’s teaching philosophy, meaning “person-oriented,” as opposed to “technique-oriented.” We don’t teach skiing to people—we teach people to ski!



Traditional acronym meaning "Independent Leg Action"—an important principle of modern skiing describing the two legs acting independently of each other, whether they act simultaneously or sequentially. Independent Leg Action includes and enables such things as the rotary mechanism of "independent leg rotation," the ability to extend and flex and tip the legs independently, stepping movements, and so on. It provides versatility that lacks when the legs act as a single unit, as in a locked or closed stance—even in situations like powder skiing when the two legs may appear to act as one, independently.



A confusing acronym with at least two very different meanings: it can stand for "Inside Leg Retraction," or for "Independent Leg Rotation." As such, it is its own best argument for why we should generally avoid the use of acronyms!


Inside leg retraction refers to an active weight transfer technique (its counterpart is "outside leg extension" or "OLE") that causes the body (center of mass) to move laterally, often used to "force" the body to cross over the skis to initiate a new turn (an appropriate movement whenever we need to force that outcome—but not the "default" movement of smoothly linked turn transitions—see "Transition," and "X Move"). It is sometimes also used simply to describe the natural shortening (flexing) of the inside leg as the body inclines (leans) into a turn—similar to the shortening of the uphill leg when standing across a hill.


Independent Leg Rotation refers to the rotary mechanism (mechanical principles for turning the skis and managing angular momentum) also known as the "fulcrum mechanism." It is also commonly referred to as "Independent Leg Steering," or "ILS." Other rotary mechanism categories include "Rotation," "Counter-Rotation," and "Blocking" (and their various sub-categories). 



"Independent Leg Steering." See "ILR" above, and for more information, see "Fulcrum Mechanism."



leaning the center of mass into a turn to compensate for and balance against centrifugal force; affects, but cannot be adjusted to control, edge angle; compare with Angulation

Inclination & Angulation

Inclination is not the same as "banking," which is simply a special case of inclining the entire body into a turn without angulation. Inclination happens in all turns that involve balance, and it can combine with angulation or not—the two are separate and independent movements serving different purposes.

Individual Teaching Style
teaching strategy that encourages student independence—student performs task and critiques his own performance, followed by evaluation of the critique from the instructor)

tendency of a body to resist acceleration (to remain at rest or continue in constant straight-line motion unless acted upon by an external force); a function of mass

Inertial Force
does not cause acceleration, but is felt as the result of acceleration; centrifugal force is an example

Inertial Frame of Reference
in mechanical analysis, this is the point of view of a “stationary” observer, in which skiing motion is described relative to the ground, where inertial forces (centrifugal force) are merely effects of acceleration and only the applied forces that cause acceleration are considered


Inside Leg Retraction

See "ILR."

Internal Rotation
describes the turning activity of the outside leg in a turn or of both legs “toes-in” in a wedge

a movement of the foot and ankle describing tipping the sole of the inward, toward the other foot (as opposed to eversion).


Inversion and Eversion of the foot and ankle


exercise involving lifting the inside ski and crossing its tip over the outside ski to develop good stance, one-footed balance, and countered hip alignment

Javelin drill, featuring FIS Moguls World Champion Patrick Deneen

Kick Turn
A simple and eminently practical technique for making a 180-degree turn while standing in one place

Copper Mountain instructor Donnie Mechalke and others demonstrate the Kick Turn

awareness of body positions and movements, resulting from proprioceptors in muscles, tendons, and joints

KISS Principle
“Keep It Simple, Stupid”

Lateral Learning
exploring technical and tactical options, varied conditions, speeds, and terrain, and movement patterns “off the Center Line™” to broaden the skill base and enhance versatility; lateral learning involves learning something new—focusing on a new challenge or movement, rather than on getting better at what you're already doing. Skiing, like most things, involves learning in both directions.

tendency of the inside ski and inside half of the body to move ahead in a turn, resulting primarily from the independent steering action of the legs, as well as the differing degrees of hip and knee flexion of the inside and outside legs.

turns initiated with an exaggerated extension, resulting in a hop off the snow and a mid-air edge change (an exercise that develops balance, accurate movements of the CM, and flexion-extension movements)

Learning Style
individual preference for acquiring knowledge primarily through doing, watching, feeling, or thinking; also a bias toward visual, auditory, or kinesthetic senses

controlling pressure fore and aft on the skis; part of the skill group of Pressure Control

tough, elastic tissue that connects bone to bone and supports joints

Linear Learning
moving “up” the Center Line™ toward a higher milestone of skill development with the same fundamental movement patterns—getting better at doing one thing, as opposed to "lateral learning," which implies learning something new.


Linear Motion

Motion of a body in a line, along a path; contrast with angular motion, which describes the motion of spinning or rotating about a point.

Lycra (Spandex)
type of fabric that should not be worn by everyone



"Movement Analysis" (see)

Maslow’s Hierarchy of Needs
model of basic human needs and motivations in order of priority from most basic and essential (survival needs) to higher order needs (security, social, self-esteem, and finally self-actualization); lower needs must be met before higher needs (learning to ski is one) become motivators

Maslow's Hierarchy of Needs; note that the lower two tiers can be "satisfied" (when you're hungry, you eat, and you're no longer hungry), while the higher needs cannot—when you get some, you want more, and they continue to motivate perhaps even more strongly

"stuff"—measure of the quantity of matter of an object

Massed Practice
single extended training session, which may be useful for initial learning of a new move or concept, but is usually less effective than “distributed practice” (several briefer, intermittent sessions)

goal of a good ski lesson—the level of learning at which students can practice a new concept or movement accurately and consistently on their own, without the instructor’s constant feedback

steering skis from a wedge to a parallel relationship, as in a Wedge Christie; it involves steering the tips of both skis into the turn, as opposed to pulling the ski tails together (“closing”)

This illustration of the ski movements of modern Wedge Christies shows skis matching to parallel in frames 8 and 9, with neither ski tail ever twisted, pushed, or pulled toward the outside of the turn (no "negative movements").

branch of physics dealing with forces and their interactions with physical objects

oriented toward what happens—teaching focused on technique, rather than on students; compare with humanistic

systematic manner of accomplishing a goal or objective; compare with technique



Man-made or naturally formed bumps in the snow surface that vary from very small to "Volkswagon"-sized. Skiing moguls well requires mastery of basic skills with extraordinary versatility and adaptability, along with strong tactical awareness to choose effective lines on the fly. Reliable short turns, disciplined upper body with a solid and well-timed pole plant, and powerful, accurate, fore-aft and "vertical" flexion-extension movements are all critical to skiing moguls.


Basic Bump Skills


There are many ways to ski bumps—diverse strategies, lines, and tactics ranging from quick, machine-gun short turns of the "zipper line" to graceful, swooping arcs that follow troughs like a bobsled track.



Lines and Creativity in Moguls

the “quantity of motion” of an object, a function of its velocity (speed and direction) and its mass

any factor that incites and guides behavior; the psychological reasons we do what we do

Movement Analysis
observing and describing the movement patterns of skiers, including cause-effect analysis and a prescription for improvement; addresses who, what, where, when, how, and why. Often abbreviated "MA."

Negative Movements
Movements away from the direction of the turn, as in movements to the skier's left in a right turn. Negative movements include tipping the skis uphill to set the edges and create a "platform" in preparation for a "pushoff"-type turn, twisting the ski tail(s) out into an intentional braking skid, and any movements uphill to initiate a turn down the hill. Negative movements are the hallmark of defensive, braking techniques.

See "positive movements" for a video illustration of the opposite movements of offensive turns (positive movements) and defensive turns (negative movements).

Negative Reinforcement
increases probability of a behavior when it is removed—example is learning a better stance because it eliminates pain in the thighs

Negative Transfer
occurs when prior experience or learning interferes with new learning, as in the water skier who habitually leans back in his boots on snow skis

In relation to ski turns, "neutral" suggests an attitude or position when not turning—uncommitted to turning, but prepared to move any direction. In linked contemporary turns, “turn neutral” describes the inflection point where one turn ends and the next begins, marked by the edge release (also, the point at which the paths of the center of mass and the feet cross and the skier is, therefore, vertical with no inclination to either side). As it is the moment a turn begins, “neutral” is a position from which the least possible amount of effort or movement is required to start the turn. It is the key to the apparently effortless, gliding, smoothly linked turns of experts.


 "Turn Neutral"—the moment a new turn begins—the end of one turn and the beginning of the next, when turns are linked, as the red circles indicate. It is the point at which the paths of the feet and the center of mass cross, when viewed from directly overhead. Because turns generally begin at some angle across the slope, the "default" characteristics of turn neutral include 1) some degree of "counter" and uphill tip lead, as the legs are rotated in the hip sockets, 2} skis approximately level—not flat on the snow—and at "critical edge angle" (see), and 3) somewhat more pressure on the downhill or new inside ski—not "50:50." (Note that real turns will often show situation-based variations from these "default" characteristics.)


Characteristics of neutral in turn transitions include 1) edge release, but skis not necessarily flat on the snow; 2) center of mass directly over feet, with balance favoring the downhill foot and centered beneath the ankle, shins centered in the boot cuffs; 3) legs rotated to some degree in the hip sockets, resulting in some lead of the uphill ski and uphill half of the body (“counter”).

Note that other definitions of “neutral,” such as “rotary neutral” (skis pointing straight ahead with no lead), “edge neutral” (skis flat on the snow surface), and “pressure neutral” (balance 50-50 on both skis) also occur in basic turns, but (contrary to popular opinion?) they all occur at some point after the turn begins. They do not occur at “turn neutral,” where the old turn ends and the new turn begins, as described above.

Newton’s First Law of Motion
The "Law of Inertia"—A body at rest will remain at rest, and a body in motion will remain in constant, linear motion, unless acted upon by unbalanced, external motive force.

Newton’s Second Law of Motion
The change in a body’s motion (acceleration) is proportional to the size of the force applied, and in the same direction as the force (F = ma)

Newton’s Third Law of Motion
For every action, there is an equal and opposite reaction; for every force, an equal and opposite counter-force—explains the principle of “counter-rotation"

Oblique Gate
double-pole race gate set diagonally on the hill 




"Outside Leg Extension." Refers to actively (involving muscular effort) lengthening the outside leg of the upcoming turn (by extending the ankles, knees, and/or hips) in order to cause a "weight transfer" which forces the body (center of mass) to cross over the skis and into the new turn. The counterpart or alternative movement is "ILR" (see), or "inside leg retraction," but both of these techniques should be considered, at best, as bookends of a spectrum of non-exclusive "situational" movements that we use only as needed—which is to say, only when we need to force a lateral movement of the center of mass (in any part of a turn). In the smoothest transitions, and by "default," the center of mass already travels on a path that crosses the path of the feet as it exits the previous "shaping phase," and no extra "forcing" exertions are needed. (See "X Move" for more on this topic.)


Outside Leg Extension may also refer to the natural—either active or passive—lengthening of the outside leg in most turns as the inside leg shortens (flexes), simply to allow, or as a result of, inclining the body into the turn—similar to the naturally different leg lengths when just standing across the hill.


Open Gate
double-pole race gate set horizontally across the hill. (See illustration above under "oblique gate.")

Open Stance
natural, uncontrived (not "wide"), functional spacing of the legs and feet with enough separation to allow independent leg rotation and natural weight transfer, balancing, and edging movements

Open Stance Parallel
Also known as “Basic Parallel” (see) it is the third Center Line™ Milestone, representing the “Common Threads” at a low intermediate level.


Outside Leg Extension

See "OLE."

refers to a skier, typically “bow-legged,” whose skis have too much edge angle when in a natural stance; cant wedges thicker toward the outside can help.

error in which the skier uses too much rotation to begin a turn, often resulting in tail washout; requires the skier to edge and check to stop the turn before starting the next

Perceptual Skills
adjustments or adaptations to basic movements based on input from the senses, as opposed to repeating the same movements strictly from muscle memory (“habitual skills”)

Pivot Slip
a drill involving sideslips directly down the hill, linked by continuous, deliberate, smooth 180 degree pivots of both skis; ideally, all rotary movement takes place below the pelvis as the femurs rotate independently in the hip sockets (see "fulcrum mechanism"), but in practice, some twisting also occurs in the lower spine, allowing the pelvis to rotate slightly after the femurs have rotated to their limit.

As a drill, Pivot Slips develop the "independent leg rotation" movement critical to modern skiing. They also reinforce the ability to find the sensation and fore-aft balance of "turn neutral" and release the edges and ski tips for a modern turn initiation.

Pivot Slip—click on image for larger version

Plantar Flexion
extension (ironically) of the ankle, moving the toes down away from the shin; opposite of dorsiflexion

Platform (Stationary Platform)
an edgeset prior to a turn, from which the skier steps, pushes off, or rebounds into the next turn; not a “common thread” of Center Line™ turns, where the edge angle flattens to end a turn and releases to initiate the next turn (sometimes known as a “moving platform”)


Platform Angle
coined by Ron LeMaster, this term refers to the angle of the base of the ski (or ski edge) relative to the force applied to the ski by the skier (the "line of action" or "line of balance"). Closely related to "critical edge angle" (see above), Platform Angle determines whether or not a ski grips the snow or releases and slips or skids. (Critical edge angle refers to a platform angle of 90 degrees.)



Platform angle is the angle between the force the skier applies to the ski (vertical, when still) and the base of the ski. When it is 90 degrees or less, the ski tends to hold; when more than 90 degrees, the skier's force literally pushes the ski out of the groove it cuts in the snow, causing the ski to slip off its "platform" and release its grip. Controlled through "angulation" movements in the ankles, knees, hips, and spine, Platform angle is unrelated to edge angle on the snow, as the second illustration shows.


For a detailed discussion of Platform Angle and Critical Edge Angle, refer to the EpicSki thread, "What is best edge angle for maximum grip?" beginning with post #17.


Pole Plant
The skier's pole plant can range from a firmly engaged stab of the snow for balance recovery or blocking to a light touch of the snow or even just a swing of the pole with no snow contact`, that enhances timing, rhythm, and "flow." There is no specific, "correct" pole use for every turn, and many expert turns will not involve a pole plant at all.


A nice pole plant!

Polygon of Sustentation
the base of support for a skier, defined as the area between the skis and extended to the pole plant when the poles are used for support or balance


 Polygon of Sustentation


Positive Movements
Movements in the direction of the turn (as opposed to "negative movements," away from the turn). In contemporary offensive turning technique, all intentional movements, including rotary, edging, and pressure control (flexion-extension) movements, tend in the direction of the turn—in a right turn, nothing moves (intentionally, at least) left. Positive Movements represent the unifying principle of technique in modern offensive turns.

Good turns are "offensive," not defensive in intent. They are intended to control direction, not speed, to "go that way," not to "stop going this way." They are about gliding, not braking. Positive movements are the fundamental elements of all good, offensive turns, the primary distinguishing factor that differentiates them from defensive braking. The following video animation illustrates the fundamental technical differences between offensive turns with positive movements, and defensive "turns" with negative movements:

Positive movements of offensive turns, vs. negative movements of defensive turns.

Positive Reinforcement
anything that tends to increase the likelihood of a behavior when given—reward

Positive Transfer
occurs when prior experience or learning helps new learning, as when the skills and movements of skating help hockey players quickly learn to ski

Freshly fallen, light, and often deep snow. Untracked "bottomless" powder can be one of skiing's profoundest pleasures for strong skiers, or one of its most vexing challenges when technique or equipment are not up to the challenge. Although modern specialized wide, soft, and often "rockered" skis have made powder stashes accessible for even lower-intermediate skiers, advanced technique and offensive tactics, in which the skis glide and slice more the direction they're pointed than skidding sideways, still brings out the best of powder's sensory pleasures. For the intermediate skier, fat powder skis have made powder skiing possible. For the expert, they enhance the pallette of what is possible, technically and tactically, enabling both carved-like slicing turns and brushed, "skarving" techniques reminiscent of surfing, at the whim of the skier.

Powder skiing, with a few brief tips for enjoying the magical condition!


A good discussion about powder skiing: "Reluctance In Powder"


an extension movement (hop) just before the crest of a dropoff, intended to minimize air time—an important move in downhill racing



Pressure Control
skill group encompassing all movements that regulate how much pressure is applied to skis, and where the pressure is focused; includes up-down, fore-aft, and lateral movements of the center of mass, primarily involving flexion and extension in various joints, particularly ankles, knees, hips, spine, and arms.

quick turn uphill or tightening of radius of the previous turn, just prior to a new turn, in order to check speed or create a platform to push off from or rebound into the next turn

Problem Solving Teaching Style
teaching strategy useful for encouraging higher levels of cognition and student independence, in which students explore and develop their own solutions or answers to a task; there may be several “right” answers

sequence of tasks that act as building blocks toward an ultimate, more complex objective

tri-planar foot and ankle (subtalar joint) movement combining eversion, external rotation, and dorsiflexion (may also describe hand/wrist motion); the opposite of “supination”

sensory receptors in joints, muscles, and tendons that detect position and relative body motion; responsible for kinesthetic awareness

unpleasant consequence of a behavior that tends to reduce the likelihood that the behavior will be repeated; should not be confused with “negative reinforcement”

Q-Angle (Quadriceps Angle)
refers to the alignment of the upper and lower leg at the knee joint and particularly the direction of pull of the large thigh muscles; tends to be larger in women than men due to the relatively wider pelvis

The Quintessential modern, basic reference standard, "benchmark" turn, representing the “default” movements and tactics of great offensive turns based on the intent to control line, to go precisely where you want to go (not to control speed directly). Fundamental principles of the Q Turn are the same at any level of skill, but specific characteristics of range, intensity, accuracy, and overall sophistication of movements vary with speed, hill angle, turn radius, conditions, and skill level.

The Q-Turn—maximally smooth and linked direction changes (mathematically, it is "continuous in all its derivatives," says EpicSki's Tom/"PhysicsMan")

As a "benchmark" or "reference," the Q-Turn hardly represents all of the critical movements, techniques, and adaptations of great skiing. It is a theoretical ideal for pure "offensive" intent to control line smoothly and effectively, with optimal biomechanical efficiency and equipment performance, on "ideal" terrain and conditions. It serves as a comparison for "real" turns, both for error identification and as a reference point to contrast with the different situational needs of real skiing.

Also known as “Center Line™ Turns” or simply, “Basic Turns,” as well as specific names that refer to the Q Turn at increasing levels of proficiency: Wedge Turn, Wedge Christie, Basic Parallel, and Dynamic Parallel.

The Quintessential Turn—the standard, benchmark reference turn that embodies the "default" technical principles of modern skiing at any level of skill

Ramp Angle
refers to the degree of fore-aft “tilt” of the footbed in the boot, resulting from the angle of the

zeppa (boot board) and any internal heel lifts or wedges on the zeppa or the footbed, inside the boot. Raising the heel of the foot inside the boot increases ramp angle. Also known as "Zeppa Angle," and not to be confused with Delta Angle, ramp angle affects the degree of ankle flexion and can be an important adjustment in boot fitting. It does not directly affect the forward lean angle of the shins (as delta angle does).


“springing” into a new turn from the energy stored in the skis and body during a brief, harsh edgeset or preturn (minimized in most modern high-performance turns)

Reciprocal Style
teaching strategy in which students are paired and given a simple task in which one is the “doer” and other the “observer” responsible for feedback

any consequence that increases the frequency or likelihood of a behavior; “positive” when adding the stimulus encourages the behavior; “negative” when removing the stimulus encourages the behavior

Letting go of the ski's or skis’ grip on the mountain in order to begin a new turn, through either reducing the edge angle (“flattening”) or reducing the pressure (“unweighting”); modern offensive turns, by default, involve release by flattening as the paths of the body and the feet cross.


This video clip shows skiers practicing and demonstrating smooth edge release through flattening from a standstill and from a gliding traverse:


passive absorption movements, as in “softening” the legs over a washboard section

active flexion; actively pulling the legs and feet “up” beneath the body, as when absorbing large moguls

Retraction Turn
turn transition in which the edge change occurs during an active flexion (shortening) of the legs


Reuel Christie (Royal Christie)

Also known as the "Flying Christie," the Reuel (pronounced "Royal") Christie was a popular freestyle move, particularly in the 1970's and 1980's. Developed by German Dr. Fritz Reuel in the 1920's, it involves turning on the inside ski while lifting the outside high and behind, upper body leaning forward with arms spread wide for balance. Done well, it is a graceful, elegant, soaring turn that is both fun to do and fun to watch!



Reverse Camber
the bending that occurs in skis along their length when properly edged and pressured in carved turns

Rise Line
imaginary line directly uphill from a point (usually uphill from the turning pole of a race gate); in race strategy, it typically indicates the optimal point at which to begin a turn around a gate.

skill group encompassing all movements that control twisting, steering, or pivoting skis and/or that affect angular momentum (“spin”) of the skier-ski system

Rotary Mechanisms
mechanical principles that allow pivoting and steering the skis (also called “turn initiating mechanisms”; not to be confused with “turning forces”); they include rotation, counter-rotation, “fulcrum turning,” and blocking pole plants, as well as deflection from the snow

Rotary Pushoff
rotary mechanism, a sub-category of “rotation,” in which the skier “throws” himself into a turn with an extension from a platform created by setting the edges of one or both skis

rotary mechanism (see) in which the skis turn as a result of stopping or slowing the rotation of the upper body, hips, arms, or other parts of the body (based on the Law of Conservation of Momentum).


Please note that "Rotation" refers to this specific rotary mechanism (others include "counter-rotation," "leg rotation," and "blocking"). Do not mis-use the term "rotation" to refer to the "rotary skill."


 Rotation mechanism simulated on a rotating barstool. Upper body (or some part of it) "winds up," then rotates into the turn. When it stops or slows its rotation, the momentum transfers to the lower body and skis. Importantly, the barstool must have enough resistance to turning to allow the "windup" and initial upper body rotation (part "1") to occur without the stool turning the other way--just as, on skis, the mechanism requires a "platform" with an engaged edge during the upper body rotation phase. Without this resistance, the barstool (and legs) would simply counter-rotate simultaneously but in the opposite direction of the upper body, and there would be no net angular (rotational)  momentum generated in the "ski/skier system."



acronym for "Sequential Leg Rotation" (see)

Sequential Leg Rotation
"SELR"—turning first one leg then the other, each leg using the other as the support against which it is moved; includes stemming, stepping, and other “one-two” leg actions. Opposite of "Simultaneous Leg Rotation," which refers to both legs turning at the same time (but not necessarily at the same rate).


"Super-G," or "Super Giant Slalom"—the second-fasted (behind Downhill), and involving the second longest turns, of the four classic alpine race disciplines of Slalom, Giant Slalom, Super-G, and Downhill.

the built-in curve of the edges of a ski that gives it an hourglass shape (narrow in the middle, wider in the tip and tail); some modern skis meant primarily for powder have “reverse sidecut,” being widest in the middle.


Sidecut refers to the curved shape of a ski edge. Sidecut radius (not to be confused with "turning radius") is the size (radius) of the circle described by the ski's sidecut.



Sidecut works with pressure on an edged ski to cause the ski to bend into reverse camber to carve turns.



Simultaneous Leg Rotation (see below)


Simultaneous Leg Rotation
"SILR"—turning both legs and skis at the same time, as opposed to turning them one-at-a-time (“sequential leg rotation”). Simultaneous Leg Rotation is a characteristic of parallel turns, naturally, but it does not necessarily imply that the legs rotate at the same rate, as in wedge christies, which also involve SILR. 

Combining "carving" and "skidding," skarving ("skarved turn") is a recently-minted term descriptive of the surfing-like deep powder slashing turns made possible by today's very wide, soft, rockered specialized powder skis. Unlike traditional narrower skis, these skis easily slip and skid sideways through powder, as well as slicing through it like carved turns, enhancing the spectrum of technical and tactical possibilities for the expert skier.

Ski Bunny
Alpinus Lapinus curvaceous—Popular game creatures (popular if game!) unique to ski country, ski bunnies are only occasionally spotted on the slopes. Capable of surviving solely on raw, green currency, the species is generally most active at night. Highly vulnerable to predators, especially in spring when they begin to shed their heavy winter coats, L. curvaceous is not yet on the endangered species list, perhaps due to high reproductive success. Ski bunnies are seldom dangerous, but they are unpredictable in captivity and often resist attempts at domestication.

See also Lycra, Inclination, and Spontaneous Christie.


 Rare photograph of a live Alpinus Lapinus curvaceous specimen, by the Lange ski boot company; poster available at vintageskiworld.com


sideways slippage of the skis as they go around a turn; all turns involve some skidding; excessive skidding can result from technical error or weakness or inadequate equipment, or from an intent to brake instead of turn.

learned or acquired capabilities, specific to a particular activity; compare with ability

Skills Concept™
the technical foundation of PSIA’s American Teaching System, it describes all skiing movements in terms of Rotary, Edging, and Pressure Control skills, all subject to the master skill of Balance. Learning to ski involves improving and blending these basic skills.



Short for "slalom."


"SL"—the quickest-turning and lowest-speed of the four classic alpine racing events of Slalom, Giant Slalom, Super Giant Slalom (Super-G), and Downhill. Slalom turns average approximately one per second.

movement of skis in the direction they’re pointed (straight ahead or back); compare with slipping, carving, and skidding

movement of skis sideways; compare with sliding, carving, and skidding


Snow Cat

A large tracked vehicle designed to move and groom snow, capable of maneuvering through extremely deep powder. The workhorse of modern ski areas, with various attachments snow cats can pack and smooth fresh powder or grind ice into softer snow. Plows and other attachments move snow and shape terrain features and half pipes. Other snow cats are outfitted to carry passengers, where they can provide backcountry access to fresh tracks. "Winch cats" use cables to enable snow cats to operate on extremely steep terrain.

A fleet of snow cats creating "corduroy."


A winch cat on the steeps of Copper Mountain, Colorado.


Razi—another kind of snow cat....



a challenging skiing drill, ostensibly named after great Austrian 1950's-era ski racer Toni Spiess, involving vigorous pogo-stick-like hops from one set of edges to the other, rotating the legs while in the air, with minimal forward movement down the hill.

Spiess drill demonstrated by Aspen instructor Toni Sears



Blowing, swirling, drifting snow whipped up from the ground by the wind.



Sports Diamond™
a simple and elegant framework for understanding critical, mutually dependent principle elements of performance and learning in any sport—and many other activities. Envisioned and brilliantly described by Aspen instructor and EpicSki Academy coach Weems Westfeldt in his book, Brilliant Skiing, the Sports Diamond™ defines Power, Purpose, Touch, and Will as the four corners of the Diamond. Embracing all four elements and shifting focus with agility provide the map to great performance, learning, and ultimate enjoyment—to “Brilliant Skiing Every Day.” (Click here, or on the link above, for more on Weems's vision and book.)

Weems Westfeldt's "Sports Diamond™​"

using muscles to maintain control of the direction the skis point; as in driving a car, steering may include gentle guiding actions (usually) or harsh emergency pivoting actions, or anything in between, or may involve simply holding the skis straight in a straight run. “Steering a turn,” like steering a car, also implies that the ski edges (or tires) grip sufficiently to control the path of the skier.

brushing of one or both skis (“double stem”) out into a converging (tails out, tips in) relationship

Stem Christie
classic turn initiated with converging skis—the "stem phase"—followed by a “christie phase” of parallel skis on corresponding edges. The stem can be either an "upstem"—pushing the tail of the uphill (new outside) ski out to a skidded turn entry as the downhill ski holds its edge—or a "downstem," in which the downhill ski tail twists downhill at the end of the turn until its edge engages, allowing a "pushoff" of the uphill ski and body uphill and into a skidded turn entry.


Stem Christie. Turn begins from an edgeset/platform of the downhill ski. First the uphill tail is twisted out (stemmed), then weight is transferred to the new outside ski and the inside ski is brought parallel ("closed"). Every movement of a stem christie is a "negative movement"—a movement away from the direction of the turn—causing substantial skidding. In modern skiing, the stem christie is a defensive action, in contrast with the "wedge christie," which involves entirely positive movements.


Do not confuse the stem christie with the modern "wedge christie." While superficially similar—both begin with a wedge phase and end with skis parallel—the two are actually polar opposites in both technique and intent. Stem christies begin with an edge set and a pushoff of first one and then the other tail out to a skid. Wedge christies begin with an edge release and both tips guided simultaneously down the hill and into the turn—movements fundamentally identical to those of offensive, gliding and carved turns, with no push or twist of either tail into a skid. Stem christies serve a defensive intent; wedge christies result from offensive "GO" thoughts. Stem christies involve entirely "negative movements" (movements away from the turn); wedge christies involve entirely "positive movements."

lifting and displacing a ski into a new position, usually used as part of a turn initiation; not a “common thread” of Center Line™ turns

tri-planar motion of the foot and ankle combining inversion, internal rotation, and plantar flexion (can also describe hand/wrist motion); the opposite of “pronation”

options intentionally chosen to optimize success, efficiency, or enjoyment

ski design factor describing the difference in width of the tip (usually wider) and tail

Task Teaching Style
teaching strategy in which the instructor gives students a specific activity to practice, but allows the students some freedom to choose where, when, and how to practice while giving some, but not constant, feedback

Teaching Model
a plan, framework, or system for lessons that helps teachers impart understanding, motivation, and skill and optimizes students’ power to learn

specific way of performing a task or applying skills; compare with method

a turn or skiing stance in which the outside ski leads the inside ski, opposite the typical alpine skiing stance; a common technique on nordic (free heel) equipment

Telemark, by Rocky Mountain instructor trainer and examiner Patti Banks (left) and legend Dave Pine, both at Arapahoe Basin

tough, fibrous cord that attaches muscle to bone

“twisting force” created when an applied force acts through a lever arm, as in turning a nut with a wrench

Torsional Flex
the amount of resistance of a ski to twisting about its long axis; higher performance skis, designed to hold and carve on firm snow, are usually much stiffer, torsionally, than skis intended for beginner and intermediate skiers, which are more forgiving and more easily manageable, but do not grip nearly as well.

Torsional flex--"twisting"

the concept in education that previous experience or learning affects current learning, either enhancing it (positive) or hindering it (negative); implies also that effective teaching today should provide the foundation for learning tomorrow—it should never need to be “untaught”!

the phase in linked turns, also known as the "float phase," that combines the end of one turn and the beginning of the next; the edge change occurs here, along with any weight transfer, although pressure on the skis is minimal to none; distinguished from the "control phase" or "shaping phase," which is marked by edge engagement and increased pressure against the skis as the snow presses against them to help shape the turn


Many pointed discussions of the transition have taken place at EpicSki over the years. Here's a recent good one, from the 2014-15 season: Instructors: do you teach moving forward at initiation? If so, how? Or why not?. My post #6 in that thread includes additional links to many more good discussions of the mechanics of the transition.

(verb) to ski straight across or diagonally across the hill; (noun) a traverse is a path across a slope

Turning Forces
external forces that cause turns—they include primarily gravity and ski-snow interaction (the "push" from the snow on ski edges), and to a lesser extent, pole-snow interaction and wind. (See "Forces in Turns" above.) "Turning Forces" must not be (but too-commonly are) confused with “rotary mechanisms” that are the principles involved in twisting or pivoting the skis; most turning forces involve all three fundamental skills (rotary, edging, and pressure)

refers to a skier, typically “knock-kneed,” who must exaggerate angulation movements to get the skis sufficiently edged. Cant wedges thicker toward the inside can help.

momentarily reducing the pressure on the skis to make it easier to twist them in a new direction or push them into a skid

Uphill Christie
“J-shaped” turn in which the objective is to glide as far as possible back up the hill

VAK (Visual-Auditory-Kinesthetic)
concept suggesting that most individuals are biased toward one physical sense or another—eyes, ears, or feeling (proprioception)—and may be most effectively “taught” through emphasizing that preferred sense

a property that describes both speed and direction of motion, easily represented by an arrow (vector)

Vertical Combination
a series of race gates set in the fall line, including “flushes” and “hairpins”; see illustration under Gates.

mental rehearsal, the ability to imagine a movement or activity

German for "tail-wagging," wedeln describes the classic technique of very short, quick turns in which fairly flat (unedged) ski tails twist left and right at two turns per second or so, resulting from powerful rotary forces from counter-rotation and blocking pole plants. Here it is, demonstrated by EpicSki's own master skier, instructor, photographer, and story-teller, Ott Gangl:

Classic wedeln, by Ott Gangl

Wedge Christie
the second milestone of skill development in PSIA's Center Line™ Model; describes basic offensive reference turns (“Q Turns”) in which skis open somewhat into a wedge at initiation, with matching from wedge to parallel during the turn. Consisting entirely of "positive (into the turn) movements," and matching the offensive intent to "go that way" (as opposed to "stop going this way"), wedge christies are fundamentally identical to parallel turns, differing only in the uneven rate of turning of the left and right skis due to novice skill development and typically very low speed. Indeed, even advanced and expert skiers will tend to make inadvertent wedge christies when turning at very low speed.

WCHS 07 numbered.jpg
Basic Wedge Christie; click on image for larger version

Wedge Turn
the first milestone of skill development in PSIA's Center Line™ Model; describes basic offensive reference turns (“Q Turns”) at a beginning level, in which skis converge (“toe-in”) to some degree throughout the turn; the wedge is not intentional, and not meant for braking, but results from the beginning skier’s difficulty in tipping and turning both skis simultaneously and at the same rate at very low speeds

WedgeTurns 07 numbered.jpg
Basic Wedge Turn; click on image for larger version

Basic Turn—Wedge

Weight Transfer
the shifting of pressure or balance from one ski to the other; typically occurs in the transition and may be active (intentional, muscularly-driven movement) or passive (resulting from the natural forces of the turn). “Transferring weight” causes a lateral force to apply to the center of mass, and is appropriately used whenever the skier needs to redirect the momentum (direction) of the body

Wind Chill Factor
combination of actual air temperature and air speed, which more accurately describes how cold it really feels on exposed skin

Descriptive term for the movements and events that occur in offensive, smooth turn transitions, in which the paths of the feet and the body cross due to their own momentum as the edges and other forces are released


  The X Move—feet (base of support, on red path) travel faster and on a longer line than the body (center of mass, on the blue path). In Dynamic turns, the feet must pass from behind, to beneath, to in front of (along the skis) the body in the transition.


"Z"-shaped, as opposed to rounded or "S"-shaped, turns typical of many beginner and intermediate skiers, or any skiers who are reluctant to let their skis glide down the hill



Also known as the "boot board," the zeppa is a part of a ski boot that determines the boot's internal "ramp angle" (sometimes referred to as "zeppa angle"). It is typically a hard plastic or foam, wedge-shaped piece that sits inside the shell on the bottom of the boot, beneath the inner boot or liner.   
Boot zeppa is the solid wedge-shaped board inside the shell, upon which the inner boot sits. It determines the boot's "ramp angle" or "zeppa angle."
Zeppa Angle
Also known as "ramp angle," zeppa angle refers to the degree of forward tilt of the footbed, largely as a result of the shape of the zeppa, or "boot board." It is not the same, nor does it serve the same functions, as delta angle, which refers to tilting the entire boot forward or back as a result of binding design or shims or ramps inserted beneath the bindings or under the boot soles. Zeppa angle affects ankle dorsiflexion inside the boot, and can be an important boot adjustment, but contrary to common mis-perception, it does not directly affect forward lean of the lower legs.

Zeppa angle (ramp angle) affects the degree of dorsiflexion of the ankle inside the boot (green angles), without directly affecting the forward lean angle of the lower legs.


See also Ramp Angle (synonym), and Delta Angle and Forward Lean.


Zipper Line
a mogul tactic and style particularly well suited to, and representative of, competitive-style mogul skiing on specially prepared courses; skiing directly downhill in the fall line at high speed, with only the skis moving rhythmically left and right as they follow the regular zig-zag zipper-like path of moguls and troughs

Competitors, including Olympian, multiple World Cup winner, and World Champion Patrick Deneen, British Olympian Ellie Koyander, and mogul and big mountain competitor Willi Furr, demonstrating Zipper Line mogul skiing at its finest.


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