1. THE BIOMECHANICS OF POLE VAULTING Scott Simpson

2. Why me?! Sport and Exercise Science Graduate at UWIC (1 st Class Hons.) – 2003 Specialising in Biomechanics 2004-2007 – PhD at UWIC entitled “Biomechanical Contributions to the Triple Jump” – Papers presented at ISBS, 2007 (Brazil) Pole vaulter – 1993-Present Pole vault coach – 2003-Present Most significantly – Peter asked me!

3. Not Biomechanics!!! Typical response! Importance can not be overstated The TECHNICAL MODEL of any event is based on the principles of biomechanics It is the STYLE that the athlete adopts that is determined by their physical characteristics Ultimately, the vaulter starts their approach run looking to find a solution to a problem, not add more problems

4. Background Information Definition: “Biomechanics is the science concerned with the internal and external forces that act on a human body and the effects that these forces produce” (Hay, 1999) Biomechanics Kinetics Kinematics

5. Background Information Kinematics Displacements, velocities & accelerations Linear or angular Units of measurement (m, ms -1, ms -2 ) (°, °s -1, °s -2 ) Methods for measurement (video, speed gun (LAVEG), timing gates) Most commonly examined variables in sporting environments (simplicity of measures)

6. Background Information Linear Kinetics Inertia, mass, force (internal and external), weight, momentum, impulse Energetics – mechanical energy: kinetic energy / potential energy / strain energy

7. Background Information (Hay, 1993)

8. Background Information Linear Kinetics Inertia, mass, force (internal and external), weight, momentum, impulse Energetics – mechanical energy: kinetic energy / potential energy / strain energy Units of measurement (kg, N, J) Force platforms/sensors, strain gauges Theoretical consideration given; not often measured

9. Background Information Angular Kinetics Centre of mass Torque/Moment (rotational force) (M = Fx) Couple – 2 sites of force application Moment of inertia (I = mr 2 ) Angular momentum (L = Iω) Axes of rotation (3 axes) Transfer of momentum – segmental to whole body Units (Nm, kg.m 2, kg.m 2 /s)

10. Background Information Newtonian Laws 1.) A body will continue in it’s state of motion unless acted on by an external force 2.) The rate of change of momentum is proportional to the force causing it and in the direction the force acts (F = ma) 3.) For every force that is exerted on by one body on another, there is an equal and opposite force exerted by the second body on the first AND THEIR ANGULAR EQUIVALENTS

11. Pole Vaulting on Paper The height which a pole vaulter is credited can be thought of as the sum of 4 component heights: - H 1 – CM height at take-off (Take-off height) H 2 – The height that the CM is raised while in contact with the pole (Swing height) H 3 – The height that the CM is raised after pole release (Flight height) H 4 – The difference between the bar height and the peak height of the CM (Clearance height)

12. Pole Vaulting on Paper Component heights in pole vaulting performance: H 1 Take-Off Height H 2 Swing Height H 3 Flight Height H 4 Clearance Height (Hay, 1993)

13. Pole Vaulting on Paper Data: Height Bar Height Component Height Sergey Bubka: 1.83m 5.85m H1 1.30m H2 4.45m H3 0.37m H4 -0.27m % of Bar Height: H122% H275% H3 6% H4 -3%

14. Pole Vaulting on Paper Each of these 4 heights will be determined by a number of other factors:- (Hay, 1993)

15. Pole Vaulting on Paper Each of these 4 heights will be determined by a number of other factors:- (Hay, 1993)

16. Pole Vaulting on Paper H 1 - Optimising body position to maximise CM height at take-off. Upright trunk, arms pushed tall, take-off leg fully extended, non-take-off leg driven upwards

17. Pole Vaulting on Paper H 1 – Optimised! Maxim Tarasov Launder & Gormely

18. Pole Vaulting on Paper H 1 - Optimising body position to maximise CM height at take-off. Upright trunk, arms pushed tall, take-off leg fully extended, non-take-off leg driven upwards H 3 - Maximising vertical velocity at release (athlete becomes a projectile where only gravity acts)

19. Pole Vaulting on Paper H 3 – Epitomised! Sergey Bubka Pole Released Vertical velocity at release allows for H 3

20. Pole Vaulting on Paper H 1 - Optimising body position to maximise CM height at take-off. Upright trunk, arms pushed tall, take-off leg fully extended, non-take-off leg driven upwards H 3 - Maximising vertical velocity at release (athlete becomes a projectile where only gravity acts) H 4 - 1. Body position – piked position (CM location) 2. Movements – use of angular momentum and transfer of momentum

21. Pole Vaulting on Paper H 4 – Exemplified! Toby Stephenson

22. Pole Vaulting on Paper H 4 – Optimised! Toby Stephenson

23. Pole Vaulting on Paper H 4 – Optimised! Toby Stephenson

24. Pole Vaulting on Paper H 4 – Optimised! Toby Stephenson

25. Pole Vaulting on Paper

26. H 2 – Swing Height Best considered from an ENERGETICS perspective.

27. Pole Vaulting on Paper Kinetic Energy at Take-Off: - E k = 1/2mv 2 Where: m = mass v = velocity e.g. Vaulter of mass 80kg with a take-off velocity of 8.5ms -1 has Kinetic Energy: 2890 Joules

28. Pole Vaulting on Paper Strain Energy at Take-Off: - Any energy stored in the pole at the instant of take- off. Force transmitted to pole via hands

29. Pole Vaulting on Paper Forces imparted on the pole by the hands – resolved into perpendicular and parallel components

30. Pole Vaulting on Paper Strain Energy at Take-Off: - Any energy stored in the pole at the instant of take- off. Force transmitted to pole via hands Perpendicular forces 1.) Bottom hand rotates pole around its transverse axis 2.) Combination of the perpendicular forces of both hands creates a couple causing the pole to bend

31. Pole Vaulting on Paper Strain Energy at Take-Off (cont.): - Parallel forces 1.) Can not translate the pole due to the box, so only serve to rotate it via pole bending 2.) The greater the angle of take-off the less the magnitude of the parallel component of force 3.) Lower take-off angles increase this parallel bending force magnitude

32. Pole Vaulting on Paper Work done during ascent: - Double pendulum 1.) Athlete pendulum 2.) Athlete-pole pendulum First priority – rotate pole to position to exploit recoil and enable bar clearance Moment of inertia – distribution of mass around point of rotation (metronome effect)

33. Pole Vaulting on Paper Work done during ascent (cont.): - Moment of inertia: 1.) Length of pole chord

34. Pole Vaulting on Paper Changing lengths of the pole chord from take-off to pole release

35. Pole Vaulting on Paper Work done during ascent (cont.): - Moment of inertia: 1.) Length of pole chord Grip height

36. Pole Vaulting on Paper Velocity @ TO: x: 9ms -1 y: 2ms -1

37. Pole Vaulting on Paper Work done during ascent (cont.): - Moment of inertia: 1.) Length of pole chord Grip height Amount of pole bend 1.Apply force with arms to increase couple 2.Swing free leg (s) – Newton’s 3 rd Law

38. Pole Vaulting on Paper 1.) Applying force with arms = increase in magnitude of couple and increase in pole bend 2.) Swinging free leg = increase in parallel forces and increase in pole bend

39. Pole Vaulting on Paper Work done during ascent (cont.): - Moment of inertia: 1.) Length of pole chord Grip height Amount of pole bend 2.) Athletes mass distribution Moving “inside” top hand Position of limbs

40. Pole Vaulting on Paper

44. Work done during ascent (cont.): - Moment of inertia: 1.) Length of pole chord Grip height Amount of pole bend 2.) Athletes mass distribution Moving “inside” top hand Position of limbs Store more energy in the pole (strain energy) that can be utilised later

45. Pole Vaulting on Paper Mechanical Energy Losses: - Interaction of pole with the box and forces within the pole itself result in mechanical energy being lost in non-mechanical forms (sound, heat etc…) Kinetics Energy at Release: - Surplus energy that does not contribute to swing height, but is responsible for flight height

46. Pole Vaulting on Paper Relationship between kinetic energy and potential energy: - At takeoff Large kinetic energy Small potential energy At peak height Large potential energy Small kinetic energy

47. Pole Vaulting on Paper (Bogdanis and Yeadon, 1996)

48. Pole Vaulting on Paper Using energy parameters to predict performance: - E k = 1/2mv 2 E p = mgh Using this: - H = (v 2 - v bar 2 )/2g Where:v = horizontal velocity at takeoff v bar = horizontal velocity over the bar g = acceleration due to gravity

49. Implications for Coaches Maximise Take-Off Height - ? Maximise Swing Height - ? Maximise Flight Height - ? Maximise Clearance Height - ?

50. Implications for Coaches Maximise Take-Off Height Choose tall athletes (!) Optimise body position at take-off Placement of take-off foot Efficiency of planting action Stride pattern to take-off (long-short)

51. Implications for Coaches Maximise Swing Height The single most important factor that contributes to pole vault success is the speed at takeoff (Bergemen, 1979). Generation of maximum controllable speed (Ganslen, 1979) Take-off angle Body positioning in flight phase Arm actions on the pole Leg action in the swing

52. Implications for Coaches Maximise Flight Height Body position Hip action Arm action Maximise Clearance Height Bar clearance position Transfer of momentum through body segments

53. Case Study Helsinki (2005) – World Championship (Schade et al., 2007) Men’s and Women’s Finals Variables: - Approach velocity Forces exerted in pole vault box Mechanical energy parameters and angular momentum Male vs. female comparisons

54. Case Study Key instances and parameters (Schade et al., 2007)

55. Case Study Approach velocities: - Men (11m-6m): 8.88ms -1 – 9.43ms -1 Highest recorded – Kristianson (9 th ) Lowest recorded – Blom (1 st !) Women (10m-5m): 7.51ms -1 – 8.53ms -1 Highest recorded: Rogowska (6 th ) Lowest recorded: Polnova (4 th ) Within subject positive correlation between bar height and approach velocity (except Blom!)

56. Case Study

57. Pole vault box force trace – Rens Blom

58. Case Study Pole vault box force trace (normalised) – Rens Blom vs. Yelena Isinbayeva

59. Case Study

61. No difference between male and female vaulters in angular momentum around the tranverse axis. A change since data from Syndey Olympics (2000) where female had higher angular momentum from PP to the point where CM crosses the pole chord (passive upward swing). Techniques have become closer and female vaulters are now more effective in their energy exchange with the pole.

62. Thank-you Are there any questions?