What are the Optimal Biomechanics of a Triple Axel in Figure Skating to Enhance Performance?
Introduction:
Levels of Competition:
Figure
skating competitions are run by the International Skating Union (ISU). The ISU
world figure skating championship is an annual figure skating competition
involving top figure skaters from around the world who compete for the title of
world champion (Podolsky, 1990). This event has been hosted all around the
world since 1896, with countries placing bids each year for the rights to hold
these championships. Competitive figure skating includes four major
disciplines: singles, pairs, dance and synchronized skating. In singles skaters
performs alone on the ice and combines the highest level of athleticism with
composition.
 |
| (International Skating Union, 2016)
Pair skating consists of a female skater and
a male partner who perform in highly athletic and daring program. This is similar to ice
dance which consists of a female ice dancer performing with a male partner in intricately
choreographed programs that focus on precision and
|
 |
(International
Skating Union, 2016)
|
 |
(International
Skating Union, 2016)
|
Synchronize
skating is completed in teams of twenty and everyone performs in unison on the ice.
 |
(International
Skating Union, 2016)
|
Levels of Competition:
There are six levels of competition, with each increasing in
difficultly and techniques. These levels start as low as juvenile and work
towards becoming a master. The skating performance is judged according to a set
of criteria that must be meet. Each section and every element of the sequence
is judged and has a certain base value indicated in the Scale of Value (SOV)
chart. Each judge on the panel identifies for each element one of the seven
grades of execution with each of these grades having its own positive and
negative numerical value. The grades of execution are determined by calculating
the trimmed mean of the numerical values of grades awarded by the panel of
judges. All four disciplines are judged differently and points are awarded
based on jump combinations, jump sequences, combination lifts and any other
addition elements added to the performance. In addition, points are delegated
for performances that contain illegal movements or elements such as costumes,
props, falls, late starts interruption in performance programs and music
(International Skating Union, 2014).
Major Question:
(International Skating Union, 2016)
Figure skating is a sport which
associates athletic competency with a sophisticated artistry (King, 2005).
Figure skating includes many different techniques and some of the stunts can be
quite challenging. A challenging manoeuvre which most ice skaters are unable to perform is the triple axel. This aerial stunt is an edge jump that is launched from the ice and
contains a half an extra rotation to a normal jump in figure skating (King,
2005). This is where the idea of the triple jump was established from and this
technique has 3.5 revolutions. The triple axel has four components these
being, skating, the take off, the rotation or the flight and the landing. It is crucial that
all these elements are performed correctly to ensure that the skater safely lands and that the rotations are successful. In addition, the triple axel is very
difficult as it is not similar to the other jumps performed in figure skating. The
triple axel involves the skater taking off on the outside edge of their blade
and going into a forward rotation (King, 2005). Additionally, the skater lands
on the opposite foot which they took off from and this is what makes the triple
axel so complex. This blog will look at what the optimal biomechanics of a triple axel are and how these can be used to enhance performance.
 |
| (International Skating Union, 2016)
Figure skating is a sport which
associates athletic competency with a sophisticated artistry (King, 2005).
Figure skating includes many different techniques and some of the stunts can be
quite challenging. A challenging manoeuvre which most ice skaters are unable to perform is the triple axel. This aerial stunt is an edge jump that is launched from the ice and
contains a half an extra rotation to a normal jump in figure skating (King,
2005). This is where the idea of the triple jump was established from and this
technique has 3.5 revolutions. The triple axel has four components these
being, skating, the take off, the rotation or the flight and the landing. It is crucial that
all these elements are performed correctly to ensure that the skater safely lands and that the rotations are successful. In addition, the triple axel is very
difficult as it is not similar to the other jumps performed in figure skating. The
triple axel involves the skater taking off on the outside edge of their blade
and going into a forward rotation (King, 2005). Additionally, the skater lands
on the opposite foot which they took off from and this is what makes the triple
axel so complex. This blog will look at what the optimal biomechanics of a triple axel are and how these can be used to enhance performance.
|
The Answer:
Preparation Phase:
 |
| (International Skating Union, 2016) |
Gliding:
Before
the take off the skater must glide across the ice in preparation for the jump
spin. This involves using the principles of kinetic energy, which is the energy
associated with velocity of someone's body (Blazevich, 2013). If a person
produces a greater power their body or object will attain a higher velocity, as
it will have more kinetic energy (Blazevich, 2013). This is crucial in the
preparation phase of the triple axel as the skater must gain as much kinetic
energy as possible before the take off. If the skater has more kinetic energy
in the preparation phase, they will be able to accelerate better off the ice,
allowing more air time to perform the turn.
Stroking/Crossover:
It
is important that the skater is accelerating fast in the preparation stage to
allow them to generate speed, resulting in maximum height off the ground when
executing their jump. The purpose of crossovers is to gather speed on the ice
(Fortin, Harrington & Langenbeck, 1997). During a triple axel crossovers the skater counters clockwise
in a backwards position and is used as the standard form of traveling in a
circle. This technique involves the skater's upper body to be turned into the
circle and the head to be turned to look over the right shoulder the direction
in which they are traveling. From using this technique power is generated
through the skater’s right leg as it pushes powerfully against the ice through
hip and knee extension and plantar flexion before it is crossed over the left
leg which is extended vigorously. This skill relates back to Newton's third law
of motion stating that “for every action, there is an equal and opposite
reaction” (Blazevich 2013).
Direction of Acceleration:
Controlling one’s center of mass is required to
performed this skill. This is due to the skater shifting his or her weight from one
leg to the other as they cross over each other. From this, power and speed of
this technique will arise from the scissor like motion produces with every stroke.
In instances such as these is it okay for the centre of mass to be unbalanced when
accelerating as it helps to allow center of mass to be moved backwards of the
base of support, as it will cause a backwards rotation of the body. The skaters
will generate more speed if their pre-extended knee angle were more acute as
this knee extension will create a greater velocity along with the bald of the
skate being more horizontally during push off stage. By crouching or bending
forwards the skater is able to reduce their air resistance and this allows them
to maintain a greater speed and power (Fortin, Harrington & Langenbeck 1997). The skater’s torso and
head faces the direction of acceleration, this can help to increase their speed
intern moving them faster along the ice with less force required and an
increase in movement efficiency. Angular velocity plays an important part in the preparation stage of the triple axel and it is key for the skater to increase their angular velocity, as then angular momentum will be conserved. Most professional
athletes have a tendency to enter the take off stage with a linear velocity of
approximately five meters per second. In the preparation stage of the triple
axel, the skater will turn their body form facing backwards to now facing
forward as they move towards the take off phase. When the skater makes this
turn, they will push off their left skate, as angular velocity refers to the rate of change in angle (Blazevich, 2013).
Take Off Phase:
Applying Greater Force Off The Ice:
The triple axel jump in figure skating is heavily influenced
by Newton's third law of motion. This law states that for every action, there
is an equal and opposite reaction (Blazevich, 2013). This is very important in
the take off stage of the triple axel leading into the spin. When a vertical
force is applied to the ice the equal and opposite force stops the foot sinking
into the ice. The ice exerts an equal and opposite reaction which can
accelerate an ice skater forwards if the force is large enough to overcome
their inertia. In order for the skater to jump to a greater height they need to
overcome inertia by having a force applied against them (Blazevich, 2013). This
can be achieved be applying large and well-directed force against the ice.
Having an equal and opposite reaction with the ice will allow the figure skater
to push up and forward from the ice to start their jump. Then the skater pushes
down and back on their ice after their rotations to land successfully. In
addition, the skater needs to follow Newton's first law in this stage to push
against the ground with the same magnitude giving the propulsion of the jump.
The skater must perform this on ice the ice against a surface which is
difficult due to the fiction less nature of its surface.
Producing Greater Power:
 |
| (International Skating Union, 2016) |
Kinetic
energy is associated with the velocity of someone's body (Blazevich, 2013).
This energy is associated with motion and an object with a greater mass or
velocity has a greater energy (Blazevich, 2013). Kinetic energy is critical in the take off
phase of the triple axel and to increase the skater's performance, they need to
maximize the amount of energy used. If the skater produces a greater power
through their legs as they push off the ice, they will attain a higher velocity
as they will have a higher amount kinetic energy. The greater mass in the legs
will result in a higher take off for an object with greater mass has a greater
energy. After an extensive amount of training figure skaters should be
able to increase their fitness and perform take offs with the same amount of
kinetic energy continuously.
Conservation of Angular Momentum:
As previously stated, angular momentum is conversed during
the take off phase of the triple axel. Angular momentum refers to any mass that moves with velocity (Blazevich, 2013). In
the take off phase, generating angular momentum is important to allow it to be
conversed. Before the skater jumps off the ice their body create torque which
influences the axis of rotation. This torque provides angular impulse and this
results in angular momentum being created. When the skater moves their free leg
through during the propulsive phases of the triple axel jump, there is an
increase in angular momentum. However, when the skater is just about to take
off the ice there is a slight decrease in angular momentum.
Angular momentum is a function of the moment of inertia and the angular velocity (Blazevich, 2013). When the moment of inertia is increased the angular momentum will remain the same. When a person starts to fall in any circumstance, they will have little angular momentum and the momentum will remain until an external force acts to change it. This is evident when the skater is swinging their arms vigorously and the body tends to rotate in the opposite direction as angular momentum is reduced. This is by applying a force (torque) which is similar to the spinning phase when the legs and arms are drawn into the body.
By the skater applying force against the ice angular momentum is generated. The ice then applies a ground reaction force onto the skater. From this the skater is able to gain angular momentum and the skater's axis of rotation needs to be correct otherwise they will not spin in the flight phase. The force being applied must cause a moment or torque in which means it must be applied a distance away from the axis of rotation. The larger the torque the greater the angular momentum will be. Angular momentum is generated prior to the toe-pick as the skater brings forward the left arm and moves the right arm forwards with an extended trunk. As the skater is on the outside edge of their skate they are able to create angular impulse about the axis of rotation which transfers into angular momentum for the jump. By taking off the toe pick the skater is able to extend their trunk during the take off stage to generate vertical momentum for the jump phase.
Differences in Techniques:
During the triple axel most skaters often
utilize a skid during the take off phases. This results in them creating higher
angular velocity at take off and allows them to rotate the 3.5 times during the
flight phase. However, if the skater includes a skid there is a reduction in
their speed and no gain in angular momentum. If the skater can
incorporate this technique with a higher
angular velocity and a smaller moment of inertia they will
successfully complete the rotations required. The skater will
often extend their knee and hip in order to bring the limbs closer to their
axis of rotation. This will allow them to increase their angular velocity and
ensure their body is tight to maximize their rate of spin in the jump phase of
the triple axel.
Flight Phase:
Body and Arm Position:
 |
| (International Skating Union, 2016) |
During the flight phase of the triple axel, Newton's first
law of motion is evident. This law states that an object will remain in motion
until an external force is applied. When moment of inertia is decreased,
angular velocity increases allowing angular momentum to be conserved. Moment of inertia refers to anything where a
quantity is multiplied by distance (Blazevich, 2013). Inertia cannot be changed in value however it's
effect can be manipulated. To create a faster spin the skater needs to hold
their knees tight close together and their arms need to be tucked towards their
chest as soon as the skater is vertically straight. The
effect of moment of inertia is reduced when a skater places their arms closer
to their body as it closer to the axis of rotation. The upper body would be moving in an upwards
vertical motion due to straightening of the legs. If the skater is vertical
this allows them to increase height on their jump, allowing them more time to
perform the rotations. In addition, the skater needs to point their toes
towards the ground to enable them to successfully propel upwards, for the
moment of inertia is decreased. This allows them to generate a greater speed in
order to successfully rotate the 3.5 times. In addition, this will
allow the skater to increase their angular velocity when they take off the
ice and once they are in the air they will continue to decrease their
moment of inertia. By adopting a smaller moment of inertia the skater can
increase their angular velocity through the flight phase, whilst they are still
on the ice. Once the skater has reached the minimum moment of inertia
attainable, based on their body size they can no longer attain higher amounts
of angular velocity. This is due to the skater decreasing their moment of
inertia, as their body is already in the tightness possible rotating position.
This technique will allow the skater to successfully complete the high
revolutions in the triple axel.
Creating Greater Angular Velocity:
Angular velocity refers to the rate of change in angle (Blazevich, 2013). In
the flight phase of the triple axel it is important that the skater generates higher
velocity to allow them to complete the revolutions included during this stage. For the triple axel the skater must generate a greater angular momentum
compared to single or double axel jumps. To complete the 3.5 turns the skater
must balance the average angular velocity with the time in the air. For the
skater to attain a greater angular velocity during the flight phases they will
need to attain a minimum moment of inertia quicker when they are in
the air. For optimal technique the skater should delay their landing by
flexing their hips and knees during the last rotation. This allows the skater
to rotate quicker thought the air and complete the maximum amount of
revolutions, as it is creating a downward force against the ice. In addition, during the flight phase the skater will perform the spin in a tight position, but then they must flex their body in order to decrease angular velocity in preparation for landing. At the same time the skater will flex at the hip and knee of the take off leg to alter its moment of inertia prior to and during the landing. This will enable them to slow down and to have successful landing.
Increasing Flight Time:
 |
| (International Skating Union, 2016) |
The amount of time in the air which a
skater has is very important in the triple axel, as it requires many rotations.
During the flight phases of the triple axel all the joins in the kinetic chain,
(feet, knees and hips) simultaneously extended vertically to generate higher
cumulative forces. This results in a push like movement pattern which results
in a higher overall force. in addition, flight time is dependent on the vertical velocity
which the skater generates and the difference in centre of mass height at take
off.
Projectile motion is crucial in the flight phase to increase flight time. Projectile motion refers to the motion of an object which is projected at an angle into the air (Blazevich, 2013). This is influenced by the gravity and the air resistance of the object. In figure skating the skater can either move between horizontal and vertical, but gravity works to keep the body in a vertical motion. During the flight phase of the triple axel jump projectile motion is influencing how long the skater can stay in the air, before returning to the ice. This allows them to complete the rotations and keep their body vertical towards the ice. In addition, the trajectory of the skater is influenced by projection speed and the height that an object is projected. This means the skater must aim to be as high as they can off the ice whilst rotating.
Projectile motion is crucial in the flight phase to increase flight time. Projectile motion refers to the motion of an object which is projected at an angle into the air (Blazevich, 2013). This is influenced by the gravity and the air resistance of the object. In figure skating the skater can either move between horizontal and vertical, but gravity works to keep the body in a vertical motion. During the flight phase of the triple axel jump projectile motion is influencing how long the skater can stay in the air, before returning to the ice. This allows them to complete the rotations and keep their body vertical towards the ice. In addition, the trajectory of the skater is influenced by projection speed and the height that an object is projected. This means the skater must aim to be as high as they can off the ice whilst rotating.
Landing Phase:
Some skaters are known to delay the landings of their jumps. This
is achieved through hip and knee flexion just prior to landing as it will enable
them to complete their last revolution (King, 2000). Once the skater has completed their rotation the next step is to
land on the ice whilst still maintaining balance. In order for the skater to
achieve this they must achieve a goal of decreasing
the angular velocity in order for them not to continue to rotating once they
have made contact with the ice.
A
skater will typically land their jump on their right leg with their
non-supported leg (left leg) being moved into complete hip hyperextension and
complete knee extension positioning it parallel to the ice surface. Their arms
are re positioning from being tucked into the chest to being flexed and abducted
to 90 degrees at the shoulder. This will continue their moment of inertia of
their upper limbs and acts as a form of balance. Centre of mass refers to
the point at which the mass of the body is evenly distributed in all direction (Blazevich,
2013). Landing with a
trunk flexion close to 30 degrees and 60 degrees of flexion on the knee and hip
allows the skater to maintain their balance for their centre of mass will be
situated between their base of support.
Additional Information:
Footwear Worn:
The skates which the
skater wears are very important to their overall performance and are influenced
by physics. The skates allow the skater to do two things, glide over
the ice and push off the ice with the edge, which causes them to gain speed.
In speed skating the skaters use clap skates to allow them to accelerate faster
on the ice, however in figure skating a hollowed out blade is used. The blade
has three parts and has a concave edge which allows the skater two edges
to skate on. When the skater angles their foot outwards and extends their knee,
the inside edge of the blade is placed on the ice and creates friction between
the two of them. Fiction allows the skate to connect the ice and this gives the
skater the resistance as they move. When the edge exerts a force onto the ice,
fiction propels the skater forward. When the skater has low fiction with the
ice it allows them to easily glide over the surface. In addition, the skate
allows the skater to dig their skate into the ice in order to go around a turn,
speed up or stop.
The skates which the
skater wears are very important to their overall performance and are influenced
by physics. The skates allow the skater to do two things, glide over
the ice and push off the ice with the edge, which causes them to gain speed.
In speed skating the skaters use clap skates to allow them to accelerate faster
on the ice, however in figure skating a hollowed out blade is used. The blade
has three parts and has a concave edge which allows the skater two edges
to skate on. When the skater angles their foot outwards and extends their knee,
the inside edge of the blade is placed on the ice and creates friction between
the two of them. Fiction allows the skate to connect the ice and this gives the
skater the resistance as they move. When the edge exerts a force onto the ice,
fiction propels the skater forward. When the skater has low fiction with the
ice it allows them to easily glide over the surface. In addition, the skate
allows the skater to dig their skate into the ice in order to go around a turn,
speed up or stop.
When a skater is at
rest on the ice the fiction between the skater's blade and the ice is zero.
Once the skater propels themselves forward by pushing off the ice with a force
perpendicular to the skate blade they are able to move across the ice. When the skate is
on the ice, there is less air flow. This allows the skater to stick on the
surface for a longer period of time. In addition, when a skater pushes
off with their rear leg, a perpendicular force is exerted on the skate by the
ice. The force points forward as that is the direction of motion and this is
what pushes the skater forward. As the skater moves across the ice they switch
to the other leg, by pushing off the ice with that one and then the process is
mirrored. If the skater pushes off the ice with a greater forward force they
are able to accelerate faster across the ice and increase the component of
force in the direction of motion. For a skater to maintain
their balance when accelerating forward, the skater will crouch forward in the
direction of motion. This will prevent them from falling backwards, due to the
torque caused by the forward component of the force. When the skater is landing
the ground reaction force end of their skate is bent, otherwise they would slow
down.
How Else Can We Use This Information?
Dance:
Dance is very similar to the techniques
of figure skating; however, it is not performed on the ice. The previous
information can be transferred to certain dance techniques such
as leaps, pirouettes and moving turns. Pirouettes require great
balance and this is achieved when the bodies centre of mass lies within
the base of support. If the centre of mass moves outside the base of support
balance cannot be reached. When a dancer prepares for
their turn their positioning is with arms put straight horizontal to the ground. From
this, the dancer then makes their way
to third position where take off begins. This is where they
aim to produce a greater power through their legs through pushing off the floor
to spring their body up into relive. The greater mass in the legs
will result in more momentum with greater mass has a greater energy.
As the dancer springs up their arms swing in to come close
to their chest with elbows facing
outwards decreasing their moment of inertia. As noted above the
effect of moment of inertia is reduced when a skater places their arms closer
to their body and their free leg is closer to the axis of rotation.
Ice Hockey and Speed Skating:
These biomechanical principles can also be applied to sports
such as, ice hockey and speed skating. Both of these sports are played on ice,
therefore how the player skates and the friction with the ice is
similar. The low friction of the blade with the ice is what allows the hockey
players and speed skaters to glide along the ice. This is similar to the
previous statements above and how the skater prepares for the triple axel. The
physical makeup of the ice also allows the skaters to dig in with their skate
to either turn, speed up or stop whilst in a game situation or skating. For a
hockey player to successfully retrieve a puck they must push off the ice with
force perpendicular to the skate blade. As the friction of the blade is almost
zero, this is the only way which they can propel themselves forward. Speed skaters use different skates, which can be referred to as clap
skates to allow them to accelerate faster, as previously mentioned. On the
contrary, hockey players have a slight hollow in the bottom of the
blade. This creates sharp edges which grip onto the ice to allow the
player from slipping. In addition, this blade must be kept sharpened
to maintain optimal performance to ensure the player's foot does not slip on
the ice.
Reference List:
Blazevich, A. J.
(2013). Sports biomechanics:
the basics: optimising human performance. A&C Black.
Fortin, J. D., Harrington, L. S., & Langenbeck, D. F. (1997). The biomechanics of figure skating. Physical Medicine and Rehabilitation, 11, 627-648.
International Skating Union,. (2016). Home. ISU. Retrieved 10 June 2016, from http://www.isu.org/en/home
King, D. L. (2000). Jumping in figure skating. Zatsiorsky VM, Biomechanics in Sports: Performance Enhancement and Injury Prevention. Oxford: Blackwell Science, 312-325
King, D. L. (2005). Performing triple and quadruple figure skating jumps: implications for training. Canadian Journal of Applied Physiology, 30(6), 743-753.
Kuehn, K. (2015). Newton’s Laws of Motion. In A Student's Guide Through the Great Physics Texts (pp. 261-264). Springer New York.
International Skating Union,. (2016). Home. ISU. Retrieved 10 June 2016, from http://www.isu.org/en/home
King, D. L. (2000). Jumping in figure skating. Zatsiorsky VM, Biomechanics in Sports: Performance Enhancement and Injury Prevention. Oxford: Blackwell Science, 312-325
King, D. L. (2005). Performing triple and quadruple figure skating jumps: implications for training. Canadian Journal of Applied Physiology, 30(6), 743-753.
Kuehn, K. (2015). Newton’s Laws of Motion. In A Student's Guide Through the Great Physics Texts (pp. 261-264). Springer New York.
Podolsky, A., Kaufman, K. R., Cahalan, T. D., Aleshinsky, S. Y., & Chao, E. Y. (1990). The relationship of strength and jump height in figure skaters. The American journal of sports medicine, 18(4), 400-405.
Smith, A. D. (2000). The young skater. Clinics in sports medicine, 19(4), 741-755.
By
Kristie Sonntag and Juliet Rapetti.
