Maximum Velocity Technical Model

advertisement

Maximum Velocity-

Technical 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

Download