Dr. Peter McGinnis-The Pole Vault Puzzle-Putting the Pieces Together(Web)

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?


� 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?


� 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)

2012 TRIALS SUPERCLINIC Dr. Peter McGinnis

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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


2

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)


� 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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� Largerlatticedfoampits(1984)

(4.83 - 6.15 m ~ 15’10 1/4 – 20’2)


� Largerlatticedfoampits(2008)

(4.83 - 6.15 m ~ 15’10 1/4 – 20’2)


� 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


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 gain



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


• Tall and lean

• Fast


• Tall and lean

• Fast

• Experienced


• Tall and lean

• Fast

• Experienced

• Patient


• Tall and lean

• Fast

• Experienced

• Patient

• Smart


• 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.


MEN


WOMENWOMEN


WOMEN

MEN

Men: h = 0.61v - 0.085

Women: h = 0.87v - 2.73


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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MEN


MEN


MEN


� 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)


� 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)


� 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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� 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.


• 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


� Minimize energy losses due to braking

� Avoid reaching and overstriding


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� Should a vaulterland heel first…?(American record holder and Olympic Silver Medalist)


� Should a vaulterland heel first, flat footed ….?(Olympian)


� Should a vaulterland heel first, flat footed or on the ball of the foot?(Olympic Gold Medalist)


� Should a vaulterland heel first, flat footed or on the ball of the foot?(Olympic Gold Medalist and former world record holder)


� 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


� 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


� 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)


� Few if any current elite vaulters – none in the U.S. – are off the ground when pole strike occurs.


� 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.


� Positive contact angle - step is on or out - free takeoff.

� Negative contact angle - step is under - less likely to be a free takeoff.


� No correlation between contact angle and height cleared

� Slight positive correlation between contact angle and vault efficiency.


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� Negative correlation between contact angle and inversion angle.


� 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


� 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


� 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


Takeoff

� Maximize displacement possible in work equation

� U = F•d + T•� Max values for d

and are limited by body dimensions

d

Follow Through


� Maintain upright posture

� Fully extend left leg


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Follow Through


� 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


� 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


� Trunk horizontal

� Left leg has caught right leg

� Shoulder axis of rotation


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Maximum Pole Bend


� 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


� Continue swinging towards end of pole

� Timing with maximum extension velocity of pole


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Start of Extension - Inversion


� Maximum hip flexion

� Shins on pole� Shoulder axis of

rotation� Shoulders slightly

below hips

Extension, Inversion & Turn


� Continue swing and pull past top of pole



� Body aligned with pole

� Right arm close to body

� Pole still slightly bent


� 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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Documents

Dr. Peter McGinnis-The Pole Vault Puzzle-Putting the Pieces Together(Web)