Transcript Sprinting - Complete Track and Field

Maximum VelocityTechnical Model
Ron Grigg
Jacksonville
University
Maximum Velocity Defined
Top End Speed Running
Occurs after complete acceleration
Requires highly coordinated movement
and appropriate sequencing of
muscle activation
Speed = Stride Length x Stride Rate
Seems simple, BUT
Stride Length and Stride Rate are
Inversely Proportionate
Must find optimal balance without
artificial manipulation
2 Components of Stride Rate
Air Time- there is almost no difference
in air time results of sprinters of ALL
abilities
Ground Time – the BEST sprinters
spend less time on the ground.
BUT HOW?
FORCE!!!!!!!
Greater force applied at ground contact
improves BOTH stride length and stride
rate.
Greater force = greater displacement=
greater SL
Greater force= repelled from the ground
faster= greater SR
Therefore “BIG FORCE, SHORT TIME”
BUT HOW?
POSTURE
When Posture is correct, movement of
limbs is often correct.
When Posture is incorrect, movement
of limbs CANNOT be correct!
POSTURE
Proper Posture = stability
Instability= dysfunctional movement=
loss of elasticity
Limb movement originates in the
CORE
POSTURE
DYNAMIC STABILITY of Core
-strong muscles around spine
-slight posterior tilt of pelvis
-maintain ability for hips to move
*oscillation & undulation like a
kayak paddle
POSTURE
HEAD, NECK, SPINE neutrally aligned
Allow for freedom of movement,
relaxation, enhanced elastic energy
return
Enhances FRONTSIDE mechanics,
limits BACKSIDE mechanics
Examining Sprint Stride
Stance Phase
Instant of Ground Contact to
moment of toe-off
Flight Phase
Actions in air when not in contact
with ground
Stance Phase-Ground Contact
Foot as close to Bottom Dead Center
as possible to minimize breaking
forces
Tibia (shin) perpendicular to track
Thighs in line with each other
knee to knee at contact
Stance Phase-Ground Contact
Must absorb impact forces in initial
stance phase
Failure (collapsing) due to poor
posture or lack of leg stiffness
Failure to properly prepare during
flight phase (will be discussed)
Stance Phase-Ground Contact
Body travels over and in front of
support foot.
From absorbing forces, to applying
vertical and horizontal forces.
Stance Phase-Ground Contact
Active forward upward movement of
swing leg thigh will increase forces
applied to ground on stance leg
Swing foot steps over opposite knee
with heel tight to buttocks while
thigh is moving forward, NOT before
Stance Phase-Toe Off
Posture!
Opposite hip forward and up
Thigh moving toward high knee
position which places hamstring and
gluteal muscles on stretch
Stance Phase-Toe Off
The best sprinters also Toe Off closer
to Bottom Dead Center due to
increased vertical force production.
Cue: “Push Up”
Flight Phase-Backside
Minimize Backside Mechanics
Knee flexion after toe off (heel to butt)
is a result of aggressive hip flexion
(high knee) once athlete has left the
ground
Flight Phase-Frontside
Opposite leg has reached high knee
position
Thigh forcefully accelerates down and
back towards the ground.
Lower leg will naturally “open up”
Flight Phase-Ground Preparation
Must prepare for Stance while in Flight
Elite Ground Contact Times of less
than .10 require prior preparation in
order to exhibit appropriate force in
such short time.
Flight Phase-Ground Preparation
ANKLE- weakest link in leg spring
system
Neutral or slight dorsiflexion position
• allows contact to be close to BDC
• puts gastroc-soleus on stretch for
better elastic force production
Arm Swing
To counterbalance the rotary
momentum of the legs
Contribute 7% to VERTICAL forces
Originates from the shoulders
MUST open and close at the elbow
Continuous Loop
Position of limbs during swing phase influences
capacity to produce force through increased
stretch of muscles
Position of limbs in flight directly influence their
positioning at ground contact
Position of limbs at ground contact affect
magnitude and direction of force application
Force applied during ground contact influences
swing kinematics immediately following toe-off
References
Dyson, Geoffrey- Mechanics of Athletics,
1977
Mann, Ralph- Mechanics of Sprinting and
Hurdling, 2011
Young, Mike- Maximum Velocity Sprint
Mechanics