EXSC 541 Chapter 6 Acceleration.docx.pdf

CHAPTER 6 – ACCELERATION

Acceleration

oIntention matters – work smarter, not harder

oSpeed is a trainable attribute

You can make an athlete faster, but you can’t make a slow athlete fast

oNot all training is equally effective

Phases of acceleration

oStart + initial acceleration

0-10 m

Longer CT – due to need to overcome inertia

More important to produce force during this time as we work to

increase momentum

Shorter FT

Forward body lean – increases propulsive force

oTransitional acceleration

10-20 m

Intermediate CT

Intermediate FT

Becoming upright body position

oApproaching top speed

20+ m

Shorter CT

Longer FT

Upright body position

oGreatest magnitude of increases in velocity will typically occur w/in first 8 steps during

early acceleration

Cueing for speed – acceleration

o“Snap the blade open” – ensures the start is a full commitment

o“Scissor the things” – drive legs both forward and back

Front side mechanics (i.e. recovery leg) w/ low leg recovery is important in

sprinting, not just back side mechanics (driving leg)

Explains the bit of toe drag during initial acceleration – emphasizes low leg

recovery

o“Punch the knees forward” – emphasizes front side mechanics w/ leg recovery

o“Drive the ground back” – you’re not just trying to spring into it, but trying to drive

through the ground

Mechanics of acceleration

oPropulsion and braking

First – more horizontal force and longer GCT

During initial steps (1-3) braking impulse is minimal since contact w/

ground is generally behind COG

Second – more vertical force and shorter GCT (deals w/ RFD)

Every step has both forces

Optimize body mechanics

CHAPTER 6 – ACCELERATION

Elite sprinters have disproportionately higher propulsive forces, w/

comparable braking forces

Vertical and horizontal forces

oEnough vertical force to overcome gravity AND enough horizontal force to contribute to

performance

~45 deg lean – maximizes propulsive forces while minimizing braking forces

Fully upright by about 12-14 steps or 20-25 m

Strength

oAbsolute strength – i.e. 320 lbs, 6’4”, 650 lbs deadlift

More important in sports that have external contact

oRelative strength – i.e. 170 lbs, 5’10”, 500 lbs deadlift

More associated w/ speed application

oSpeed is all about overcoming one’s own COM

Whatever force is left over after overcoming gravity is the force available for

performance

The 40-yd gold standard

oOriginally developed for football

Punt hangtime – ~4.5 s

Punt average distance – ~40 yds

oTo do top speed training, does an athlete absolutely need to sprint 40-60+ m?

oVelocity profiling – acceleration relative to top speed

Strength and elasticity

oAthlete type

Muscle-based rhino

Fascia-based cheetah

oTrain it all – but emphasize weaknesses

oStrength vs plyometrics vs speed

oConcentric strength is vital in the first steps

oTop speed requires more SSC activity

oSpeed requires coordinated strength, not isolated strength

Core – stabilize COG (stabilized strength), creates dense proximal stiffness to

efficiently transfer force and avoid energy leaks

Acceleration training – overcoming a static position w/ dynamic force production

oBasic anchor drill – wall drive plank

Lean body 45 deg w/ arms/legs straight

Streamlined position from head to heels

Apply force isometrically

Hold position for 20-30 s, 2-4 sets

oBasic – feet-exchange wall drive

Same position w/ alternating knee drive

Hold position for 2-4 s count, 4-6 reps each leg

oModerate anchor drills – sled drag

Same set up as wall drive w/ hands holding sled behind body

March forward slowly, maintaining acceleration position for 10-20 yds

CHAPTER 6 – ACCELERATION

Focus on maintaining good form and muscle activation

Goal is to drag 80-120% of BW on sled

4-6 reps

oModerate – sled push

Just push the sled dummy

Keep head above hands

20 yds, 4-6 reps

oModerate – med ball broad jump

Same 45 deg angle

Chest pass for 10-15 yds for 4-6 sets

oModerate – push up start

Set gaze 2-5 yds ahead

Repeat 2-6 reps of 5-20 yd max efforts w/ proper W:R ratio

Advanced application drills

oAcceleration ladder sprint

Drive COM as far forward as possible

Start w/ shorter strides to emphasize horizontal force production

Hold force production constant and increase frequency based in

increasing SLs

Basic application drills

oJump-back acceleration – just be careful, as this may teach “zero step”

Jump back behind line w/ both feet and explode upon landing into sprint

10-15 yd sprints for 4-6 sets

Moderate – ball drop acceleration

oDrop tennis ball 5 yds away

oRepeat 4-6 reps

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