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楼主: KuoiGuaBoarder

CSIA ---THE CANADIAN APPROACH

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 楼主| 发表于 2014-3-8 19:29:50 | 显示全部楼层

TURN PHASES

本帖最后由 KuoiGuaBoarder 于 2014-3-9 19:13 编辑


http://www.youtube.com/watch?v=Lfb_xV2BExk
Turn Phases are a way of linking a skier’s movement patterns with specific parts of the turn.
They provide a template for skill assessment and development by prioritizing and sequencing
skills.
Turn Phases as a working tool
Although sequenced from 1 to 3 for reference, turn phases can be approached in any way that is
effective for results. For example, working the timing of edging in phase 3 could be a way of
developing stance in phase 1. While turn phases provide an excellent way to break down turns,
skill development should always lead to linked, fluid skiing.
Phase 1: Completion to “neutral”

http://www.youtube.com/watch?v=D6ziBbtCX70
The skier must be balanced to manage pressure and forces generated by the turn.
The COM is released from its arc, diminishing the line of inclination. This takes the skier to flat
ski(s) between turns, and lets the COM travel freely down the hill and towards the inside of the
next turn.
The COM and the BOS come out of the turn together, with the skier in a balanced, neutral stance.
As the skis flatten, they are released from their arc, diminishing the steering angle.
Phase 2: “neutral” to fall-line

http://www.youtube.com/watch?v=fvLE2irPpog
A new turning platform is established. In parallel turns, the skier should feel the side cut of
both skis.
COM maintains its momentum, moving forward and inside the arc.
The skier stays centred in anticipation of the loading that will occur later in the turn. Steering
with the lower body creates a natural upper and lower body separation.
Phase 3: Fall-line to completion

http://www.youtube.com/watch?v=8SThrlh4eKE
The skier progressively increases edge angles through angulation. As the turn radius tightens,
steering angle increases.
To manage the external forces, parallel skis as well as legs and upper body stability are crucial.
The steering and loading is timed for direction change and/or speed control and helps to create
linking back into phase 1.
Adjusting Phases to different types of skiing
Turn phases apply to wedge turns also:
1. With equal weight on both skis, a beginner will glide between turns.
2. The turning platform is established as the skier creates balance over the outside ski
through separation and subtle angulation.
3. Edge increase is subtle, but grip with the outside ski creates deflection.
In steeps and bumps the timing of the phases change:
1. The edge release happens quickly and is often initiated with a hop or release of pressure.
2. Upper/lower body separation results from an active pivoting of the legs beneath the skier.
3. Steering is active, and helped by terrain contours. Edging later in the turn controls speed.
 楼主| 发表于 2014-3-8 19:30:50 | 显示全部楼层

BIOMECHANICS AND SKIING

本帖最后由 KuoiGuaBoarder 于 2014-3-8 19:48 编辑


Biomechanics is the application of mechanical and physical principles to body movements. It can
help explain efficient movement patterns for any sport or activity.
The 7 Biomechanical Principles have been developed by the NCCP (National Coaching
Certification Program). Instructors and coaches with a good understanding of these principles can
make better skill assessment and development decisions. The 7 principles also provide a tool to
evaluate technical trends in skiing in terms of function, not fashion.
1. Stability
Stability is increased by lowering the centre of gravity and/or widening the base of support.
Conversely a narrower stance is less stable, but can facilitate agility and quickness. This explains
why a low, wide stance is preferable for a beginner or for a racer at high speeds on an icy surface,
while an expert in bumps or soft snow may choose a taller, narrow stance.
2. Maximum force
To produce or resist maximum force, as many joints as possible must be involved. Also closely
related to stance, this principle is due to the mechanical advantage created by all the joints and
muscles working together.
3. Velocity
Producing maximum velocity requires the use of all available joints in order of largest to
smallest. This is easily seen in throwing sports. In skiing the feet are in contact with the snow, so
the sequence is less apparent and practically simultaneous. A skier needs to use the ankle, knee
and hip joints together, but the big joint (the hip) must be inside the turn for the other joints to
work effectively.
4. Impulse
Impulse is force multiplied by time, and increasing impulse increases velocity. Impulse is the
skier’s work energy added to the forces of the turn. Some of this energy will become potential
energy stored in the ski and boot that will provide kinetic energy when it is released. Impulse can
add life and rebound into skiing, but applying too much, or at the wrong time can disrupt the
glide of the ski.
5. Direction
Movement occurs in the direction opposite to the applied force. For example, a skier wishing to
accelerate can apply force at the top of the arc to contribute to direction down the hill. Similarly,
a skier wishing more direction across the hill will apply their force mid-way through the arc, and
a skier wishing to control speed will apply force at the end of the turn, effectively providing some
direction back up the hill.
6. Angular motion
Angular motion is produced by the application of force acting at some distance from an axis
(torque). In skiing, the skis act as lever arms creating torques on the body. Upper and lower body
separation is a way of resisting the torques so the skier can stay balanced. Less effort is required
to resist twisting forces if the hands are held wide. By spreading the mass of the arms out, the
skier is rotationally stabilized.
7. Angular momentum
Angular momentum is constant when an athlete or object is free in the air, and conserved when
grounded. The “spinning” forces involved in turning have momentum. If a skier is “spinning” on
ground and loses contact with the snow, the spinning will continue. Conversely the skier can
store energy like a twisting spring to manage carving and create turn linking. Stopping this
momentum with a pole plant lets the legs redirect between turns independently of the upper body.
 楼主| 发表于 2014-3-8 19:33:41 | 显示全部楼层

PHYSICS AND SKIING

本帖最后由 KuoiGuaBoarder 于 2014-3-8 19:49 编辑


Alpine skiing presents a unique physical environment. Unlike sports where speed and forward
motion are attained by internal muscular effort, in skiing gravity provides the pull while the skier
uses body movements to influence speed and direction. From a technical perspective, there are
two criteria for success:
• The ability to choose and maintain a trajectory: for the racer, their line is imposed by the race
course while a free skier chooses it according to terrain and the desired outcome.
• Efficiency: for the racer this means speed, and for the free skier it means creating any direction
change with the least amount of physical effort and resistance.
Defining Efficiency
With gravity as the primary motive force, speed in skiing has much to do with reducing braking.
Carefully timed muscular effort can also contribute to speed, if the skier “pushes” in a way that
compliments gravity. Efficiency applies at all speeds. For recreational skiers of all levels
controlling direction change while conserving momentum and muscular effort produces skiing
that is balanced, relaxed and results in full control of the situation.
This approach is adaptable to the needs of all skier types, as the skier can:
• Generate and/or maintain speed wherever possible.
• Control speed when necessary or desirable.
Movement and Motion - 20 years as a technical perspective
The concept of movement and motion was introduced by the CSIA as a perspective on the sport
of skiing. First presented at Interski in 1983, it still successfully explains observed movement
patterns at all skill levels and situations.
Movement and Motion defines balance in skiing as the relationship between the COM and BOS.
Movements are what the skier does to influence the line of mo-tion, or the path of the COM. As
the mass moves down the slope it seeks the path of least resistance, or the most direct line. To
change direction, the skier places the skis, or BOS, at an angle to the trajectory of the COM and
edges them. Skiing on an arc is a series of deflections, with the BOS supporting and deflecting
the COM on every point of that arc.
With the overall goal of being able to follow a chosen trajectory at a chosen speed with the least
possible resistance and muscular effort, the skier must move constantly to maintain balance and
control direction change.
Technique vs. methodology
Technique: theoretical or scientific analysis of balance and movement patterns of skiers
according to the principles of physics and biomechanics.
Methodology: practical tools for skier development used by instructors and coaches to develop
good technique in skiers.
A good technical understanding does not necessarily imply effective use of methodology.
Similarly, use of methodological tools should be based on theoretical understanding of technique.
FORCES IN SKIING
A skier sliding down a slope is held to the slope by a portion of the force of gravity acting
perpendicular to the slope. Another portion of the force of gravity acting parallel to the slope
pulls the skier forward and down the hill.
Opposing these forces is the friction between the skis and the snow, and the friction of the air
against the skier.
Turning adds two other forces. Centrifugal force pulls the skier away from the centre of the arc.
To continue turning, the skier resists this pull, creating a centripetal force.
Combined forces
Above the fall line centrifugal force and gravity pull in different directions, and after the fall line
they combine. Gravity and centrifugal force create a combined resultant force. The angle of the
resultant force is the line of inclination that the skier adopts to stay in balance.
BALANCE WHILE SLIDING AND TURNING
Balance is defined in the relationship of the Centre of Mass and the Base of Support. The COM is
supported by the BOS at whatever angle is appropriate to resist outside forces.
The Centre of Mass
All bodies have a Centre of Mass. The COM represents the balance point of a three dimensional
object. Gravity and all other forces act on the COM.
• The COM is usually inside an object but not always. In a doughnut for example the COM is in
the hole. It may actually be outside an irregularly shaped object.
• Due to the weight of equipment, the COM is lower in a skier than a non-skier
• The COM is not a fixed point, and moves as an object changes shape. Any body movements
displace the COM. As efficient skiing implies a smooth trajectory of the COM, any unnecessary
movement can adversely affect balance. Expert skiers control their movements so the COM
smoothly moves both within the body and down the slope.
The Base of Support
For a body to balance, the force acting through the COM must also act through the BOS. This
means the BOS supports the COM.
• The BOS is the area between all points that support the body. A wider stance broadens the BOS,
increasing stability. A pole plant also momentarily increases the BOS.
• Balancing over a smaller BOS is also possible, although the forces required to push the skier
over are less. A smaller BOS gives less margin for error.
Maintaining Balance
A skier balances with continual series of adjustments in anticipation and reaction to the
combinations of forces encountered. To stay in balance the skier must be able to adjust either
COM or BOS quickly. Because the lower body has less mass than the upper body, quick
adjustments are often made with the feet (BOS).
Overcoming resistance
Heavy snow, skidding, edging or bumps can continually or momentarily increase ski/snow
friction, or resistance. To stay in balance the skier compensates by moving the BOS forward
relative to the COM so that forces continue to act through the centre of the ski.
MOVING ON AN ARC
When the COM is moving it has momentum. On an arc, the COM wants to fly off in a straight
line called a tangent. The tangent at each point on the arc is the direction of travel at that point in
time. The most natural position for balance is facing the direction of travel. This is why the hips
and torso face slightly to the outside of the turn at any point in the arc.
The angle between the tangent of the arc of the COM and where the skis are pointing is called a
steering angle. With the skier facing the direction of travel, a longer radius turn will show a
smaller steering angle than a short radius turn.
Ski sidecut provides a built in steering angle between the centre axis of the ski and the flare of the
tip. This steering angle decreases down the length of the ski, hence the tips provide more turning
 楼主| 发表于 2014-3-8 19:34:55 | 显示全部楼层
TECHNIQUE - THE CANADIAN APPROACH
The Canadian Approach to ski technique combines theoretical knowledge with practical tools for
skier development. It is the shared approach of the Canadian Ski Instructors’ Alliance and the
Canadian Ski Coaches Federation.
1- Technique (technical base)
Together, physics and biomechanics are the technical tools that provide the theoretical knowledge
for effective skier development. Biomechanical principles and physics apply to all sports and
activities and can help to understand why skiers balance in certain ways and use particular
movements.
Physics and skiing: physics is the foundation of ski technique. With gravity providing the primary
motive force, a skier balances and interacts with the forces provided by an ever changing ski
environment.
Biomechanics and skiing: an understanding of practical biomechanics links ski technique to
physics, and helps to describe efficient and effective body movements.
2- Methodology (assessment and development tools)
These teaching methods provide a structure for skier assessment and development and are the onsnow
development tools that instructors and coaches use.
Turn phases link a skier’s movement patterns with specific parts of the turn. They can help in
prioritizing and sequencing skills.
Planes of balance are a way to analyze a skier’s balance as they move in curved trajectories down
the mountainside. They provide a method for identifying balance problems and respond with
targeted skill development.
Skill development is the core of the Canadian approach. It is a way of understanding all skiing
through 5 elements. The skills system identifies areas for development, and uses a tactical
approach to improve abilities.
发表于 2014-3-8 19:43:00 | 显示全部楼层
本帖最后由 snowrider 于 2014-6-15 01:23 编辑

..........
 楼主| 发表于 2014-3-8 19:55:55 | 显示全部楼层

Assessment

STAGE OF DEVELOPMENT TECHNICAL ABILITY

ACQUISITION
〉 The skier coordinates and executes the key
components of the movement in the correct order;
〉 Execution is inconsistent and lacks precision;
〉 Cautious execution by skier;
〉 Rough form, lacks synchronization, rhythm and
flow.
CONSOLIDATION
〉 Coordination of movements appears
〉 Controlled and rhythmical execution of task under stable
conditions
〉 Some performance elements are maintained, but
are inconsistent when skier is under pressure,
conditions change or demands increase
REFINEMENT
〉 Performance is consistent and precise in demanding
conditions
〉 Movements are automatic and done subconsciously
〉 Only minor fine tuning may be necessary
〉 Critical reflection and correction is possible by skier

Teaching:
Meets expectations (M/E) or Needs improvement (N/I).

发表于 2014-3-8 19:59:40 | 显示全部楼层
牛的牛的,明天开练!
 楼主| 发表于 2014-3-8 20:00:09 | 显示全部楼层

Development tools

本帖最后由 KuoiGuaBoarder 于 2014-3-9 19:14 编辑

Fast track to parallel


http://www.youtube.com/watch?v=uIezKwIvPPA

Beginner


http://www.youtube.com/watch?v=ytP6ZLKU50w

Intermediate



Advanced
 楼主| 发表于 2014-3-8 20:21:26 | 显示全部楼层

TERMINOLOGY



Angulation: the lateral angles formed between segments of the body.
Balance: the use of the neuromuscular system to maintain an athletic posture and alignment of the COM and BOS.

Banking: the tipping of the shoulders and the upper body into the turn. It generally is an unstable position, and it is often associated with rotation. Synonym: tipping.
Base of Support (BOS): the area between all points that support the body. It generally is referred to as the feet, but it is any point of snow contact including skis and poles.
Carving: turns with little or no skidding, with the tails of the skis following the tracks made by the tips.
Christie: a turn or part of a turn, done with the skis parallel.
Centre of Mass (COM): the three dimensional balance point of an object.
Counter-rotation: the action of upper and lower body turning against each other, based on physical principle of an action having an equal and opposite reaction. If upper or lower body are turned, the other segment will turn in the opposite direction. A weak force and most effective if the skis are un-weighted.
Cross-over: the crossing of the trajectories of the COM and BOS between turns; related to edge change.
Edge angle: the lateral angle formed between the base of the ski and the slope.
Edge change: the change of balance from one edge (or edges) to the other.
Extension: the lengthening of the body by un-bending joints. Opposite of flexion.
Fall Line: an imaginary line following the inclination of the slope at any point. Where a snowball
would roll if released on the slope.
Flexion: the shortening of the body by bending joints. Opposite of extension.
Inclination: the degree of lean used to balance against the external forces generated by turning.
Lead change: the natural tendency for the inside ski to be ahead as a result of the lower body turning.
Line of motion: the path that the COM follows.
Linking: the smooth transition between turning arcs. Related to edge change.
Movement: body actions initiated by internal muscular efforts. Can affect balance on all planes.
Parallel: a position of the skis where the longitudinal axes are parallel and edge angles are the same.
Rotation: the twisting of the hips or upper body into the turn, often causing imbalance.
Self steering of skis: the inherent turning tendency of skis, due to sidecut and longitudinal flex.
Separation (upper and lower body): refers to the steering effort being led by the lower body, with the upper body naturally facing the direction of travel, or the tangent of the arc.
Sidecut: the shape of the ski defined by the width underfoot versus width tip and tail.
Ski reaction: the use of stored energy in ski and boot to provide rebound for turn linking.
Skidding: the sideways travel of one or both skis across the snow. Necessary for speed control.
Sliding: the forward travel of one or both skis on the snow.
Steering: the blend of edging and pivoting with the control of the resulting pressure. Steering allows the skier to choose a variety of turn shapes. Different blends of edging and pivoting allow the skier to control speed or to maintain speed or accelerate by reducing braking.
Steering angle: the angle formed between the longitudinal axis of the ski and the direction of travel of the skier.
Stem: a position of the skis where the tails are further apart than the tips. Seen in Wedge (snowplow) turns as a braking or steering device, or if the tail of the downhill ski skids more than the tip.
Stepping: a step, or transferring of weight from one ski to the other.
Tipping: the tipping of the shoulders and upper body into the turn. Generally unstable position, and often associated with rotation. Synonym: banking.
Traverse: sliding forward on edges at angle to the fall line.
Wedge: ski position with tips together and tails apart. See Stemming.
Weighting/Unweighting: the control of the load or pressure against the snow. Affected by moving COM quickly up or down, by increasing or reducing steering, and by the muscular forces applied by the skier.
发表于 2014-3-8 21:58:48 | 显示全部楼层
你把党的秘密都暴露了。至少应该做点生意啊。

点评

唉, 没本事出书, 搬个砖头 整个辛苦钱  发表于 2014-3-8 22:03
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