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Biomechanics Of Sprinting. Understanding Sprint Performance. Horizontal Velocity throughout the race is constantly changing. Most Important part of the race Acceleration Maximum velocity. Start. Horizontal velocity of an elite sprinter - PowerPoint PPT Presentation

Transcript of Biomechanics Of Sprinting

Slide 1

Biomechanics

Of

SprintingHorizontal Velocity throughout the race is constantly changing.

Most Important part of the raceAccelerationMaximum velocity

Understanding Sprint PerformanceHorizontal velocity of an elite sprinterOver 4 meters/sec at ground contact coming out of blocks

Increases to over 7 meters per second by end of the 2nd touch down

That is over half of the sprinters maximum velocity with in the first 3 steps of the startStart

From powerful horizontal force to a more vertically directed force.

In part due to raising COGMechanics Transition For the Start the goal is maximum horizontal force and minimizing force in all other directions

Transition phase into maximum velocity

Once maximum velocity is reached the goal is to maintain maximum velocity by producing maximum amounts of vertical force

Basic Mechanics

This means that Horizontal velocity is not the critical mechanical factor in sprint performance

Basic MechanicsWe can understand this change in focus by looking at Newtons laws

Force= Mass(Change in velocity)/Ground time

@Start

Horizontal force=77.5*(7.0)/.60 = 905 N or 205lbs of horizontal forceNewtons Laws*77.5kg=170.8lbs@ Maximum velocityHorizontal force= 0

@ StartVertical Force= 77.5*(1.0)/.150= 485N or 110lbs

Total Vertical Force=

750N+485N= 1235N or 277lbs

Newtons LawsAs you transition into maximum velocity the horizontal force output decreases

This is not true of vertical force

Because of gravity, sprinting is a series of alternating ground and air phasesNewtons LawsTo account for this the change the vertical velocity in the upward direction must increase to about .5 m/s

This is also true in the downward direction so the total vertical velocity increase equals to 1.0 m/sNewtons LawsVertical force= 77.5*(1.0)/.087= 890N or 199 lbs

Total Vertical Force= 759N+890N= 1,640N or 367lbsNewtons LawsAs horizontal velocity increases the segments increase as well.

When segments increase it has a negative impact on the runners ability to produce vertical force

Another limiting factor is the body positionMechanicsThe body positioning of the sprinter at touchdown is actually producing horizontal braking forces

The touchdown point is actually located slightly in front of the COG

The best sprinters minimize this effectMechanics

Specific Performance DescriptorsBlock DistancesCOG Distance at Set PositionSegment Angles at Set PositionSegment Angles During Block ClearanceCOG Distance at Step 1 TouchdownSegment Angles during Step 1COG Distance at Step 2 touchdownSegment Angles during Step 2Start MechanicsHorizontal VelocityStride RateStride LengthGround Contact TimeAir TimeTime To Maximum Upper Leg FlexionCritical Performance Descriptors at Maximum VelocityThe most successful sprinters focus on front side mechanics

Active recovery of the back side mechanics is important

Do not just spin the wheels

Front Side/ Back Side MechanicsHunter,J., Marshall,R., McNair,P.(2005). Relationships Between Ground Reaction Force Impulse and Kinematics of Sprint-Running Acceleration. Retrieved from: Journal of Applied Biomechanics, 21,31-43Kovacs,M. Speed Training: Linear Acceleration. Retrived from NSCACavagna, G., Komarek, L., Mazzoleni, S. (1971, May) The Mechanics of Sprint Running. Retrieved from: The Journal of Physiology, 217, 709-721Mann, R. (2011). The Mechanics of Sprinting an Hurdling. References