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