(A HURDLER’S ATTEMPT AT) DEFYING GRAVITY

ANN MARIE KELLY THE HISTORY OF :

• c. 1830: 100 yard hurdles introduced in

• Heavy wooden barriers • 1896: 110m Hurdles ➡

• Lighter-weight hurdles • 1932: Women’s Hurdle Races- 80m • 1972: Women’s 100m Hurdles at the Olympics EVOLUTION OF HURDLING TECHNIQUE: • Original hurdles ➡ heavy wooden barriers • Likely to knock over runner upon impact • Primitive technique • “Bundled” Jumps • Tucking legs under bodies • Center of gravity must get high enough in the air for shins/ankles to clear EVOLUTION OF HURDLING TECHNIQUE:

• Modern Day Hurdles ➡ “L-Shaped” • Weighted, but lighter and can “run through” them • Men’s 110 m hurdles: 10 x 3 ft. 6 in. hurdles (42 in.) • Women’s 100m hurdles: 33 in. • Distance= 110m, 100m

Distance Number of Hurdles Height Run-up Intervals Home Stretch 100m 10 33 in 13m 8.5m 10.5m 110m 10 42 in 13.72m 9.14m 14.02m • Modern Day Technique= “Gliding” over hurdles • 3-step technique • Lead leg vs. Trail leg “GLIDING” TECHNIQUE OVERUSE INJURIES: MUSCLES INVOLVED • Adductor muscle strains • Adductor longus muscle • Hamstring muscle strains • Biceps femoris, semitendinosus, semimembranosus • Hip extensor strains • Gluteus maximus and hamstring muscles • Hip flexor strains • Psoas major, iliacus muscle, rectus femoris, sartorius • Knee tendonitis • patellar tendon • Sprained ankles • Shin Splints • Soleus, anterior tibialis, posterior tibialis • Quadriceps strains • Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius • Calf strains • gastrocnemius MY ANALYSIS: ORIGINAL QUESTION

• What is the biggest advantage in using true hurdling form as opposed to ”hopping” over a hurdle? WHY I CARE: WHY YOU SHOULD CARE: METHODS FOR MY EXPERIMENT

• Sony Cybershot RX10 II • 4 step run up • 30 in. hurdle height • Attempt to keep movement as constant as possible between bundled jump and hurdle. • Attempt to take off at same marker • Similar velocities coming in (14.7 and 14.1 cm/s for jump and hurdle form, respectively) • Ruler attached to base of hurdle • Video taken of stopwatch with camera to standardize time

FLAT 100 VS. HURDLES • 2012 Summer Olympics • 100m winner= Shelly-Ann Fraser-Pryce (Jamaica) 10.75 s • 100m hurdles winner- () 12.35 s • Records • 100m- Florence Griffith-Joyner (1988) 10.49 s • 100m hurdles- - 12.21 s FLAT 100 VS. HURDLES

• Difference in mechanics • 100m flat- goal= cover ground • Apply more force to ground to run faster. Lift knees and open up your stride. • Hurdling: goal= RHYTHM • If take that same approach as flat sprinter, they will run up on the hurdles • 3-step technique. • Staying low over hurdle and minimizing air time

• https://www.youtube.com/watch?v=2CXDtgYSrZk (5:00 min.) • https://www.youtube.com/watch?v=IzEZltNMNig (2:20 min.) X VS. Y HURDLING

X vs. Y: Hurdling

600

500

400

300 X (cm) 200 Y (cm)

Distance (cm) 100

0 0 0.2 0.4 0.6 0.8 1 1.2 -100 Time (s)

Note: For the x vs. y data analysis of both videos, the origin is set to when the hip marker enters screen X VS. Y BUNDLED JUMP

X vs. Y: Bundled Jump

600

500

400

300 X (cm) 200 Y (cm)

Distance (cm) 100

0 0 0.5 1 1.5 2 2.5 -100 Time (s)

Note: For the x vs. y data analysis of both videos, the origin is set to when the hip marker enters screen Y Value Comparison: Hurdle vs. Bundled Jump

80 (Hip Mark)

70

60

50

40

30

20

Vertical Distance (cm)Distance Vertical 10

0 Relative Time (s) Origin= 0,0 Y (cm) Hurdle Y (cm) Bundled Jump DIFFERENCE IN HIP HEIGHT CLEARING HURDLE

25.85cm difference *Bundled Jump goes 1.6 times higher than Hurdle Technique HORIZONTAL DISTANCE VS. AIR TIME

Distance Traveled X-Axis: Hurdle vs. Jump (Air Time of Trail Leg Ankle)

500

400 (cm)

Air 300 - X 3 Hurdling (ankle air time) 200

100 X 3 Jump (ankle air time)

0 0 0.5 1 1.5 2 2.5 -100 Horizontal Distance Horizontal -200 Time (s)

X Distance Traveled while in Air (Hurdle Technique)= 268.60 cm= 2.69m X Distance Traveled while in Air (Bundled Jump)= 184.15cm= 1.84m *Hurdling technique covered 1.46 times further distance than the jump! Origin: set to directly over center 45.4% increase of hurdle X VELOCITY ANALYSIS (AIR TIME)

X Velocity: Hurdle vs. Jump (Trail Leg Ankle Air Time)

30

25

20

(cm/s) 15 Vx 3 Hurdling 10 Vx 3 Jump

5 X Velocity Velocity X

0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 -5 Time (s)

Average X Velocity in Air: Origin: set to directly Hurdling: 13.51cm/s *Hurdling= 2.1 times faster over center of hurdle Jumping: 6.39cm/s VELOCITY ANALYSIS (AIR TIME)- Y AXIS

Velocity Y-Axis: Hurdle vs. Jump (Air Time of Trail Leg Ankle)

20

15

10 Vy 3 (Hurdle) (cm/s) 5

Axis Axis (cm/s) 0 Vy 3 (Jump) (cm/s) - 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 -5

-10

-15 Velocity Y Velocity -20 Time (s)

VY = VX (forward motion, moving from point A to B) • All the unnecessary effort in the vertical direction detracts from the horizontal movement, which is the main point of any running related competition Origin: set to directly over center of hurdle

COMPARISON OF AIR TIME: HURDLE VS JUMP (TRAIL LEG ANKLE)

Y 3 Hurdle (cm) Y 3 Jump (cm) 160 140 60 120 40 100 20

Axis Axis (cm) 80 - Y 3 Jump (cm) Axis Axis (cm) 0 60 Y 3 Hurdle (cm) - 0 0.5 1 1.5 2 2.5 40 -20 20 -40 0 -60 Distance Y Distance 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Distance Y Distance -80 Time (s) Time (s) Hurdle Technique Total Air Time: 0.49s Bundled Jump Total Air Time: 0.71s

• 1.45 times longer spent in air and off the ground with bundled jump technique More time off ground= letting gravity set the pace= losing your race!

• 48% increase in relative air time for bundled jump Origin: set to directly over center of hurdle DISCUSSION ON GRAVITY IN HURDLING

• Car suspension analogy

• In Hurdling: leg= spring; torso= car

• When over hurdle, trying to use leg to overcome speed of gravity that is slowly floating you back down ANGULAR VELOCITY DISCUSSION

• Hypothesis: bundled jump would have a higher angular velocity (working harder to get leg back down, whereas hurdle technique is more fluid)

• Calculationsà Angular Velocity

• Calculate slope (Thigh tan)= (Y2- Y1)/ (X2-X1) • Arctan of thigh angleà convert to degrees • Take derivative of angular position ANGULAR VELOCITY HURDLING

Angular Velocity- Hurdling Technique (degrees/sec)

200 150.90 degrees/sec 150 97.37 degrees/sec 100

50

0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 VaT -50

-100 (degrees/second) Angular Velocity Velocity Angular

-150

-200 Time (s)

Origin: set to when hip marker enters screen ANGULAR VELOCITY BUNDLED JUMP

Angular Velocity- Bundled Jump Technique (degrees/sec)

200 145.58 degrees/sec 149.36 degrees/sec 150

100

50

0 0 0.5 1 1.5 2 2.5 Ang V Jump -50

-100 (degrees/second) Angular Velocity Velocity Angular -150

-200 Time (s)

Origin: set to when hip marker enters screen THINGS TO ADDRESS:

• Center of Mass • Does not vary much between the two jumps • Compensate in hurdling form- one leg out and other behind • Bundled jumpà “clam shell.” (Center of mass shifts forward a little from weight of legs but not much) • Kinetic and Potential Energy • Different sources of energy that would skew data ADVANTAGES OF HURDLING FORM:

• Staying lower while over hurdle (less vertical distance traveled) • Covering more horizontal distance while in air • Less overall air time • *Average horizontal velocity is much faster in air than it is for the bundled jump • Vertical velocity lower while in air than was for bundled jump (less taken from horizontal velocity) • More fluid movementà as demonstrated by the angular velocity FUTURE DIRECTIONS:

• Getting back to “top speed” after hurdling vs. bundled jump • Time required • Distance required ACKNOWLEDGMENTS

• Dr. Lawrence • Dr. Frank Nelson • Dr. William Berner • Trenton Rivera REFERENCES

• Salo, Aki I. T. "Technical Changes in Hurdle Clearances at the Beginning of 110m Hurdle Event- A Pilot Study." ISBS (2002): 84-87 • McGinnis, P. M. (2005). Biomechanics of Sport and Exercise (3rd ed.). Champaign, IL: Human Kinetics.