99032723-Dr-Peter-McGinnis-The-Pole-Vault-Puzzle-Putting-the-Pieces-Together-Web.pdf
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Transcript of 99032723-Dr-Peter-McGinnis-The-Pole-Vault-Puzzle-Putting-the-Pieces-Together-Web.pdf
The pole vault puzzlePutting the pieces together
Peter M. McGinnisKinesiology DepartmentSUNY [email protected]
2012 Trials Super ClinicUSATF & VS AthleticsJune 26 • Eugene
What’s puzzling about the pole vault?
� Does a fast approach run guarantee a high vault?
� Is a free takeoff (or pre-jump) really better?
� Should a vaulter jump up at takeoff?
What’s puzzling about the pole vault?
� Should a vaulter land on the heel or ball of the takeoff foot?
� Is a double leg swing more effective?
� To row or not to row, that is the question?
What’s puzzling about the pole vault?
� When will Bubka’s record be broken –or will anyone ever break it?
� Finally - what can be done to make the event safer?
Before we continue – let’s look at the history of the pole vault.
HistoryHow has the pole vault evolved?
� Record progression
� Athletes
� Equipment� poles
� landing pits
� runway surfaces
� vault box
Wooden Pole Era (1800s)
� Heavy wooden poles ~ ash, hickory
� Sod or turned over sod landing pits
� Grass or dirt runways
� No box ~ spike or tripod on end of pole
(heights less than 3.66 m ~ 12’0)
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Wooden Pole Era (1800s) Bamboo Pole Era (1900-1945)
� Lighter bamboo poles� built in handgrips
� slightly flexible
� Sawdust, sand, sod, or wood chip pits
� Cinder runways
� Vault boxes introduced
(3.66 - 4.76 m ~ 12’0 – 15’7 3/4)
Bamboo Era
� 1912 ~ 13’0
Bamboo Era
� 1912 ~ 13’0
� 1927 ~ 14’0
Bamboo Era
� 1912 ~ 13’0
� 1927 ~ 14’0
Bamboo Era
� 1912 ~ 13’0
� 1927 ~ 14’0
� 1940 ~ 15’0Cornelius Warmerdam
194215’7 3/4
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Steel Pole Era (1945-1960)
� Man-made steel poles
� Bags of shredded foam rubber introduced
� All-weather track surfaces introduced
� Metal boxes
(4.80 m ~ 15’9 1/4)
Steel Era
� Don Bragg� 1959 – 15’9 1/4
� 1960 OlympicChampion
� Last world record seton steel pole
Fiberglass Era
� 1962 – 16’0
� 1963 - 5.00 m
� 1963 – 17’0
� 1970 – 18’0
� 1972 - 5.50 m
� 1981 – 19’0
� 1985 - 6.00 m
� 1991 – 20’0
Fiberglass Era
� 2000 Women’s pole vault introduced in the Olympic Games
Fiberglass Pole Era (1960-?)
� Light andflexiblefiberglasspoles
(4.83 - 6.15 m 15’10 1/4 – 20’2)
Fiberglass Pole Era (1960-?)
� 1986 – Nordic Sport introduces pole with carbon fiber
� Gill Athletics is now the largest manufacturer of carbon/fiberglass poles
(4.83 - 6.15 m ~ 15’10 1/4 – 20’2)
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Fiberglass Pole Era (1960-?)
� Largerlatticedfoampits(1984)
(4.83 - 6.15 m ~ 15’10 1/4 – 20’2)
Fiberglass Pole Era (1960-?)
� Largerlatticedfoampits(2008)
(4.83 - 6.15 m ~ 15’10 1/4 – 20’2)
Fiberglass Pole Era (1960-?)
� Light and flexible fiberglass poles
� Larger latticed foam rubber pits
� All-weather runways
� Vault box modified to accomodate pole bend
(4.83 - 6.15 m ~ 15’10 1/4 – 20’2)fiberglass
steelbamboo
wood
Warmerdam
Bubka
Performance progression
Strategy for solving the pole vault puzzle
• Empirical data
• Theory
• Simulation
• Experience
Basic pole vault mechanics
� Simple pole model
� Based on work and energy
� Total energy at takeoff = Total energy at maximum height
+ work done
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Work and Energy
� Kinetic Energy (KE) = 1/2 mv2 + 1/2 I2
energy due to motion
� Potential Energy (PE) = Wh = mghenergy due to height
� Strain Energy (SE) = 1/2 kx2
energy due to elastic deformation (stretching, bending…)
Work and Energy
� Work = U = F • d
Work done by a force = average force x displacement along
the line of action of the force
� Work (angular) = T •
Ei = Initial energyTotal energy of vaulter and pole at takeoff
Ef = Final energy Total energy of vaulter and pole at maximum height
Work and Energy
� If energy were conserved…
Ef = EiEf = Ei + U
U = Work done by vaulter fromtake off to max. height
Work and Energy
� But …vaulter can add energy by doing work on the pole…
Ef = Ei + U - Elost
Elost = Total energy lost during vault
Work and Energy
� However …energy losses occur during pole bending, unbending, inelastic stretching, etc…
Final energy = initial energy + work done - energy lost
Total Energy at Takeoff ~ Ei
PEi = Potential energy(cg height)
KEi = Kinetic energy(velocity)
SEi = Strain energy (pole bend)
Work and Energy
Ei = PEi + KEi + SEi
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Total Energy at Maximum Height ~ Ef
PEf = Potential energy(cg height)
KEf = Kinetic energy at max. height
Work and Energy
Ef = PEf + KEf Ef = Ei + U - Elost
Work and Energy
[PEf + KEf] = [PEi + KEi + SEi] + U - Elost
Final energy = initial energy + work done - energy lost
PEf = [PEi + KEi + SEi] + U - Elost - KEf
Work and Energy
takeoff on pole
PEf = [PEi + KEi + SEi] + U - Elost - KEf
Work and Energy
StrainEnergy
Potential Energy
+ KineticEnergy
TAKEOFF
+ WorkDone
EnergyLost
-
ON POLE
=
MAX HEIGHT OF CENTER OF GRAVITY
PotentialEnergy
-Kinetic Energy
MAX HEIGHT
+
Maximize positive elements
� Potential energy at takeoff ~ mgh
� Kinetic energy at takeoff ~ 1/2 mv2
� Work done on pole ~ F•d + T•(Any strain energy at takeoff will decrease KE at takeoff, so strain energy at takeoff should not be maximized)
Minimize negative elements
� Energy losses
� Kinetic energy at maximum height
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Energy Losses
� Occur during energy transfers and transformations
� During takeoff
� During pole bending phase
� During pole straightening phase
Energy Transformations
Schade, Brüggemann, Isolehto, Komi, & Arampatzis (2006)
Energy Transformations
Schade, Brüggemann, Isolehto, Komi, & Arampatzis (2006)
energy gain
Energy Transformations
Schade, Brüggemann, Isolehto, Komi, & Arampatzis (2006)
energy gain
Components of a 6 m vault
1.25 m ~ height at takeoff1.24 m ~ work done by vaulter
+ 3.51 m ~ takeoff velocity6.00 m vault
Components of a 6 m vault
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Vaulter Characteristics
• Tall and lean
Vaulter Characteristics
• Tall and lean
• Fast
Vaulter Characteristics
• Tall and lean
• Fast
• Experienced
Vaulter Characteristics
• Tall and lean
• Fast
• Experienced
• Patient
Vaulter Characteristics
• Tall and lean
• Fast
• Experienced
• Patient
• Smart
Vaulter Characteristics
• Tall and lean
• Fast
• Experienced
• Patient
• Smart
• Passionate about pole vaulting
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Approach Run
� Fast run
� Accurate run
Approach Run: Velocity
• A fast take off velocity depends on a fast approach run velocity.
Approach Run: Velocity
MEN
Approach Run: Velocity
WOMENWOMEN
Approach Run: Velocity
WOMEN
MEN
Men: h = 0.61v - 0.085
Women: h = 0.87v - 2.73
Approach Run: Velocity
h = predicted crossbar height cleared
Regression equation:
v = approach run velocity at takeoff
For height in meters and velocity in meters per second
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Approach Run: Velocity
MEN
Approach Run: Velocity
MEN
Approach Run: Velocity
MEN
Approach Run: Velocity
� Velocity over last 5 m of approach run is strongly correlated with crossbar height cleared (r = 0.77 for men, r = 0.83 for women)
Approach Run: Velocity
� 10.00 m/sScott Huffman (5.86 m, 1994)
� 9.84 m/sSergey Bubka (5.85 m, 1993)Dean Starkey (5.70 m, 1994)Greg Duplantis (5.70 m, 1996)Jeff Hartwig (5.85 m, 1998)
Approach Run: Velocity
� 8.96 m/sStacy Dragila (4.20 m, 2001)
� 8.77 m/sJenn Stuczynski (4.92 m, 2008)
� 8.62 m/sLacy Janson (4.40 m, 2008)
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Approach Run: Velocity
� Does a fast approach run guarantee a high vault?
� No…you must be fast to vault high.…but …just because you are fast does
not mean you will vault high.
Approach Run: Velocity
• The effectiveness of a vaulter’s technique - how much work he or she does during the vault - largely determines the difference in height achieved by two vaulters with the same velocity.
• As technique effectiveness decreases - the proportion of vault height accounted for by velocity increases.
Approach Run
� Minimize forces needed to carry pole by using pole drop technique
Approach Run – pole push?
� Minimize forces needed to carry pole by pushing the pole?
Approach Run: Accuracy Approach Run: Accuracy
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Approach Run: Accuracy Approach Run: Accuracy
Approach Run: Accuracy
� Most vaulters use a visual control strategy to correct errors in the approach run.
� Corrections begin at the start of the 4th to last step before takeoff (the 5th to last support phase).
� Coaches’ checkmarks should be placed at this step or at the start of the 5th or 6th to last steps.
Approach Run: Accuracy
Approach Run: Accuracy� Use a
checkmark at the start of the 5th or 6th to last step.
Pole Plant: Initiation
� Pole horizontal
� Right hand above hip
� Maintain good sprint mechanics
� Begins with left foot touchdown
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Pole Plant: 2nd to last step
� Slightly longer than previous steps
Pole Plant: Last step
� Right hand head high
� Left hand forward, shoulder high
� Upright posture
Pole Plant: Last step takeoff
� Right hand head high or higher
� Left hand forward and head high
� Upright posture
Pole Plant: Last step
� Upright posture
� Low knee drive
� Shorter, quicker step
Takeoff Foot Touchdown
� Minimize energy losses
� Right arm fully extended upward
� Upright posture
Takeoff Foot Touchdown
� Minimize energy losses due to braking
� Avoid reaching and overstriding
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Takeoff Foot Touchdown
� Should a vaulterland heel first…?(American record holder and Olympic Silver Medalist)
Takeoff Foot Touchdown
� Should a vaulterland heel first, flat footed ….?(Olympian)
Takeoff Foot Touchdown
� Should a vaulterland heel first, flat footed or on the ball of the foot?(Olympic Gold Medalist)
Takeoff Foot Touchdown
� Should a vaulterland heel first, flat footed or on the ball of the foot?(Olympic Gold Medalist and former world record holder)
Takeoff Foot Touchdown
� Should a vaulter land heel first, flat footed or on the ball of the foot?
This may depend on the takeoff of the vaulter:
� Higher takeoff angle – heel
� Lower takeoff angle – ball of foot
Pole Strike
� Minimize energy losses
� Heel up and on ball or toe of foot (or off ground)
� CG and hips directly above or forward of toes
� Upright posture
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Pole Strike
� Minimize energy losses
� Right arm extended upward
� Right hand directly over toes
Pole Strike – pre-jump/free takeoff
� Alan Launder (1989) Pre-jump:
“…the vaulter drives up into the takeoff and clears the ground BEFORE the pole plug hits the back of the box…”
� Roman Botcharnikov (2005)Free takeoff:“Takeoff during which the vaulter does not experience pole resistance.”
Pole Strike – Pre-jump Pole Strike – Free takeoff
1970s Free Takeoff 1970s Free Takeoff
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Research: Timing of Pole Strike
� Pole strike occurs later in support phase (closer to the instant of takeoff) for better vaulters while the vaulter is pushing back and down on the runway (during the propulsive phase of force production)
Research: Timing of Pole Strike
� Few if any current elite vaulters – none in the U.S. – are off the ground when pole strike occurs.
Research: Timing of Pole Strike
� Data from 2011:tTD = 0, tPS = 0.033s, tTO = 0.125s
Research: Contact Angle (Nielsen)
� Angle formed by line from ball of takeoff foot to shoulder at instant of pole strike.
� Backward lean is negative, forward lean is positive.
Research: Contact Angle (Nielsen)
� Positive contact angle - step is on or out - free takeoff.
� Negative contact angle - step is under - less likely to be a free takeoff.
Research: Contact Angle (Nielsen)
� No correlation between contact angle and height cleared
� Slight positive correlation between contact angle and vault efficiency.
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Research: Contact Angle (Nielsen)
� Negative correlation between contact angle and inversion angle.
Research: Contact Angle (Nielsen)
� Vaulters with free takeoffs vault high with slower approach run velocities, but they don’t invert or extend as completely.
Research: Energy (Shade & Arampatzis)
� Vaulters varied timing of pole strike
� Energy change from touchdown to takeoff measured (vaulter energy and pole energy)
Research: Energy (Shade & Arampatzis)
� Vaulter energy at takeoff greater when pole strike closer to takeoff
� Pole energy at takeoff less when pole strike closer to takeoff
� Gain in vaulter energy and loss in pole energy - no advantage for early pole strike
Pole Strike – pre-jump/free takeoff
� Is a free takeoff (or pre-jump) really better? Maybe, because it …
� Maximizes pole angle
� Allows the completion of the takeoff without the pole ripping the vaulter off the ground
� Allows greater range of motion for swing takeoff leg - greater work done during the vault
Pole Strike – pre-jump/free takeoff
� Is a free takeoff (or pre-jump) really better? Maybe not, because it …
� Is physically and psychologically challenging to learn
� Requires a more accurate step placement
� Requires greater jumping ability
� Makes inversion and extension more difficult
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Takeoff
� Maximize potential energy
� Right arm fully extended
� Right hand over left toe
� Upright posture� High knee drive
Takeoff
� Maximize kinetic energy
� Minimize energy loss� Takeoff angle ~17-
19° for men~18-20° for women
� Minimal pole bend
Takeoff
� Should a vaulter jump up at takeoff?YES The takeoff angles observed for elite vaulters (17-19° for men and 18-20° for women) can only be achieved by jumping up at takeoff. These angles are much higher than the 3-5° takeoff angles in sprinting.
Work and Energy
takeoff on pole
PEf = [PEi + KEi + SEi] + U - Elost - KEf
Takeoff
� Maximize displacement possible in work equation
� U = F•d + T•� Max values for d
and are limited by body dimensions
d
Follow Through
� Minimize energy losses
� Maintain upright posture
� Fully extend left leg
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Follow Through
� Minimize energy losses
� Stretch reflex: hip flexors, trunk flexors, shoulder extensors
Follow Through
� Is a double leg swing more effective? Maybe.
� Larger F and T possible in work equation?
� U = F•d + T•
Swing
� Maximize work done
� Whipping extended trail leg
� Hip flexors, trunk flexors, shoulder extensors are active
Swing
� Maximize work done
� Long extended body
� Arm, trunk, & leg align w/box
� 45 degree angle with runway
Swing
� To row or not to row, that is the question?Yes –paddle. Shoulder extensors are active.
Maximum Pole Bend
� Maximize work done
� Trunk horizontal
� Left leg has caught right leg
� Shoulder axis of rotation
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Maximum Pole Bend
� Minimize energy losses
� Don’t overbendpole
� 30% pole bend (chord shortens by 30%)
Maximum Pole Bend
Maximum Pole Bend Maximum Pole Bend
Maximum Pole Bend Start of Extension - Inversion
� Maximize work done
� Continue swinging towards end of pole
� Timing with maximum extension velocity of pole
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Start of Extension - Inversion
� Minimize energy losses
� Maximum hip flexion
� Shins on pole� Shoulder axis of
rotation� Shoulders slightly
below hips
Extension, Inversion & Turn
� Maximize work done
� Continue swing and pull past top of pole
Extension, Inversion & Turn
� Maximize work done
� Body aligned with pole
� Right arm close to body
� Pole still slightly bent
Extension, Inversion & Turn
� Minimize excess kinetic energy (too much rotation or horizontal velocity at release)
Bar Clearance
� Wrap around bar
Bar Clearance
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Land Safely in the Pit Injury Prevention - reduce risk
� Improve equipment
� Educate coaches and athletes
� Use rules to implement changes
Landing Pit
� Increase size
� Pad standardbases
� Pad areabetween pit and box(box collar)
Pad box area• Improve padding around
box• Replace bottom of box
with softer material• Replace steel and
concrete box with soft box
• Change rules to allow box collar padding to overlap edge of box
Be safe and have fun!
� Pole vaulters
� U.S.A. Track and Field
� U.S. Olympic Committee
Thanks to...
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