MORIN Sprint Mechanics Low Res

SPRINT ACCELERATION MECHANICS AND TRAINING

New technology, New concepts, New perspectives…

J-B Morin, PhD Laboratory of Exercise Physiology University of Saint-Etienne, France

[email protected]

Running&speed&and&acceleration&is&NOT&in&our&nature…&

Laboratoire de physiologie de l’exercice �

Studying sprint speed….why?

Lieberman et al. Nature, 2004�

Laboratoire de physiologie de l’exercice �

Life Magazine, 1955�

45 km/h


Survival of the fastest…

Acceleration is the key…


PRODUCE FORCE

« TRANSMIT IT » TO THE GROUND

REPEAT WITH HIGH RATE of MOVEMENT

VARIABLE POSITIONS and DIRECTIONS

Sprint Acceleration Mechanics – Nov. 2013

Understand - Evaluate - Improve OVERVIEW

! MEASURING*FORCE*OUTPUT*DURING*SPRINT*RUNNING*

! PRODUCE*FORCE…AND*TRANSMIT*IT*WITH*EFFECTIVENESS*

! ROLE*OF*HIP*EXTENSORS?*

! WORKSHOP:*F:V*PROFILING,*SIMPLE*FIELD*METHODS*


2010,%new%technology…%


INSTRUMENTED TREADMILLS (FORCES 3D= YES; SPRINT = NO)

CYCLE-ERGOMETERS Velocity - Force - Power

SPRINT TREADMILLS (SPRINT = YES; FORCES 3D= NO)

Validate a device that cumulates these features

-1

0

1

2

3

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Temps (s)

For

ce (B

W) Verticale

Horizontale

Existing methods…


Instrumented&treadmill&

Weyand et al., 2000 - ��

11,7 m/s !!

Realistic&Top&speed&values&Ground&reaction&force&(VTC)!&NO&Acceleration&phase&ONLY&top&speed&is&studied&NO&Horizontal&force&measurement&


•  « Push vertical to run fast »

« We conclude that human runners reach faster top speeds not by repositioning their limbs more rapidly in the air, but by applying greater support forces to the ground. » 2000

Influential sprint and top speed researches

(Peter Weyand)


Mea

n ve

rtic

al G

RF

(BW

)

6 to 12 m/s !

24 Men

9 Women Olympians

Only Vertical GRF is measured….and…


3D Ground Reaction Forces, Speed, Power, 1000 Hz, step-averaged values…



Instantaneous

Average per step

2012

New&perspectives&!&


Category: Coaching

2011,%new%concept…%


Sprint instrumented treadmill: for each step, averaged values of Horizontal, Vertical and Total Force

Pedaling mechanics, Effectiveness = Ftan / FTot = cos β

FR

FTan FTot

β Davis & Hull 1981 Lafortune & Cavanagh, 1983

1. Concept of « Ratio of Force » RF

HZT

VTC TOT

Maximise RF in sprint running does not make sense (in cycling it does) Maintain a high RF during the acceleration makes sense…


y = -0.0805x + 0.6584

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

2.0 3.0 4.0 5.0 6.0 7.0Vitesse (m/s)

Rat

io d

e fo

rces

Velocity

of

Step after step, the RF decreases…. for all athletes….

2. Decrease in the RF: Drf

Slope = index of the effectiveness of force application

onto the ground (Drf)

Step 1 Step 6

Very efficient

Not efficient


Publication in process

Similar values of GRF, linear RF-speed relationships, similar Drf values

INSEP

PB = 9.95 s

Similar to

Start

Limit: Treadmill study = Treadmill results ?


•  INSEP-Paris: 3D Force Measurements for 18 steps over 40-m accelerations •  9 elite and high-level sprinters (9.95 – 10.5 s)

What&relationship&with&sprint&performance?&

HZT

•  12 subjects (2 sprinters) •  Treadmill sprint •  Just before or after : track 100-m

S100 D4s (Team sports) vs.

« Physical » capability Force Production (Hzt, Vtc, Tot)

« Technical » ability To apply this force with effectiveness (DRF)


HZT

•  Main results…

And: FTot (BW) was not correlated to DRF

« Physical Capability » of Force Production

« Technical Ability » of Force Transmission

Significant correlations in bold

Mean Speed 100 m

4 s Distance


HZT

Subject ": Long jumper (15 yrs of practice, 100-m best time : 10.90s) Subject #: non-specialist (cyclist)

Typical example

1er pas •  Subjects 2 and 11

Sujet 11 Sujet 2

Mass (kg) 68.1 69.9

Tot Force (BW) 1.87 1.89

RF max (%) 37.1 41.3

Drf -0.051 -0.083

100 m (s) 11.9 13.66 Smax (m/s) 9.96 8.80 D-4s (m) 26.3 23.3

CONCLUSIONS: The effectiveness of force

application is more important than the total amount of force

produced

(Limited to this population…)


When sport meets science, a case study

Morin et al. 2012

200m Junior World Champ. 2008

100m: 10.28 s 2010: 9.98 s 2011: 9.92 s

9.92 s: No systematic / heavy strength training Not a « muscular » guy (best 1/2 squat ≈120 kg) At 21, only 5 yrs after his T&F debut


•  6-s sprint on the treadmill •  100-m field sprint

Ground reaction forces •  Fv •  Fh •  FTot

RF – speed Drf

y = -0.0805x + 0.6584

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

2.0 3.0 4.0 5.0 6.0 7.0Vitesse (m/s)

Ra

tio

de

fo

rce

s

Speed (m/s)


Main results…

Confirms our previous results ! How the resultant force is applied is more important than its magnitude

2011


Remember the typical subjects…

HZT

": Long jumper #: Non-specialist (cyclist)

Sujet " Sujet #

Mass (kg) 68.1 69.9

FTot (BW) 1.87 1.89

RF max (%) 37.1 41.3

Drf -0.051 -0.083

100-m (s) 11.9 13.66

Smax (m/s) 9.96 8.80

D4s (m) 26.3 23.3

CL

80.5

11.2

31.0

10.35

1.90

44

-0.042

« Take-Gym Message »

For a very similar FTot, He is able to produce 25% more HZT force…


WCS

The higher the speed, the larger the difference in RF….

Question: How can we produce high HZT force AT HIGH SPEED ???


Synchronized EMG and 3D Forces Sprint and repeated sprint (fatigue)

Foot and knee 2D motion

PRE-POST Isokinetic testing (H/Q)

2013%«%The%hip%extensors%study%»….St#Etienne,)Auckland,)Murcia)


First Results….

Isokinetic Force alone NOT correlated to ground reaction forces

EMG alone: NOT correlated to ground reaction forces

Multiple regressions: FHZT explained by: Hamstring Eccentric Force “+” EMG end of swing

Quadriceps….Gluteus….Contact Phase: Nothing

FVTC explained by: NOTHING we measured…

2013%«%The%hip%extensors%study%»….St#Etienne,)Auckland,)Murcia)


«)Prepare)and)Repair…..)»)

Importance of horizontal force production (especially at high speed)

Total force production capability: is it that important ?!

What balance between hip extensor and flexor muscle groups?

Hamstring eccentric force and activation: Performance AND Injury prevention !


TRANSMISSION


«)A)chain)is)only)as)strong)as)its)weakest)link)»)…..whatever the force of the strongest link….

WORKSHOP: F-V PROFILING IN SPRINT & JUMP

J-B Morin, PhD Laboratory of Exercise Physiology University of Saint-Etienne, France

[email protected]

EVALUATE « ABSOLUTE » MAXIMAL VELOCITY

Force as a « distorting » factor

In!ALL!these!situations,!a!certain!amount!of!force!is!produced……..!!

In!these!cases,!velocity!is!NOT!MAXIMAL!POWER!is!tested,!rather!than!«!Velocity!»!


FORCE – VELOCITY – POWER

Actual!«!maximal!»!velocity!can!be!studied!through!FJV!relationship…!

Forc

e (N

.kg-

1 )

Vitesse (m.s-1)

« V0 »

« F0 » Maximal theoretical Force and Velocity Even with no additional load (SJ), the level of force output is not negligible


OK,!how!is!it!possible!out!of!the!lab!??!


Mechanical work during the “Squat Jump” push-off

g( po )W m h h= +

p1

og

hmh

F ! "= +# $

% &

g2

V h=

g1

p 2og h hh

P m ! "= +# $

% & 2

vol

8gth =

Knees ≈90°

Start position take-off Max height

Validated against force plate 2000 Hz

High agreement, Mean absolute bias < 3%

OK WITH DIFFERENT LOADS…



Forc

e (N

.kg

-1)

Velocity (m.s-1) v0

F0

Po

wer

(W

.kg

-1) Pmax

Forc

e (N

.kg

-1)

Velocity (m.s-1)

v0

F0

Po

wer

(W

.kg

-1) Pmax

For a same given Pmax ,

Many possible profiles….

Which one maximizes performance ??

« Velocity » Profile « Force » Profile

Athlete 1 Athlete 2


2012

Concept%of%«%Optimal%FCV%ProFile%»….)


“…experimentally.supports.the.actual.existence.of.an.optimal.F6v.profile,.specific.to.each.individual,.that.maximizes.jumping.performance.for.a.same.given.!!"#...

CONCLUSION

In press


Concept%of%«%Optimal%FCV%ProFile%»….)

In progress…

!  Partnerships (football, basketball, rugby, tennis, athletics) !  First long-term follow-ups initiated all over the world !  Experiments: Training vs. Control Groups…


FORCE – VELOCITY - POWER

What!about!SPRINT!RUNNING!???!


Sprint performance analysis…

« Speed-time curves » !  1927, Archibald HILL, pioneer

What could be possible with field devices?

RADAR, GPS, Photocells, iPhone ??


v(t) = vmax.(1-e(-t/τ))

di Prampero et al., J Exp biol, 2005

a(t) = (vmax/τ).e(-t/τ))

x(t) = vmax.(t + τ.e(-t/τ))- vmax.τ

vmax

τ

A New Simple Method

Furusawa et al., 1927 Henry, 1954 Volkov & Lapin, 1979

OR

"!#(%)/"%( 

∫↑▒#(%)!"% 

Fundamental law of dynamics….


P-F-V profiling in sprinting

a(t) = (vmax/τ).e(-t/τ))

A New Simple Method

Fh(t) = m.a(t) + Fair

Samozino et al., ISB 2013, Natal

Estimated from stature and body mass (and wind if measured) Arsac & Locatelli, JAP, 2002

Ph(t) = Fh (t) . v(t)

v(t)

Ph(t) Fh(t)

F0

V0

Pmax

Samozino et al., in preparation

Inverse quasi-linear F-v relationship Parabolic P-v relationship Validity ??


!  Comparison to track force plate data (F-V, Pmax) !  Validation from radar or photocells data

Paper in preparation…

Ex. Usain Bolt’s World Record

INSEP Paris


Example: 2011-2012 Season Follow-up of Lemaitre

First meeting…

Winter…

One week before London…


TYPICAL&EXAMPLE:&The&guy&is&slow……but&has&high&velocity&capabilities&!&

& && He&does&not&seem&to&need&velocity&workout&


JUMP

Innovation: all that with an iPhone / iPad ?! « FitTests » app

SPRINT www.fit-tests.com


CONCLUSIONS…Potential applications… STUDIES IN PROGRESS

M. Buchheit

J. Mendigutchia

P. Edouard


M. Brughelli

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MORIN Sprint Mechanics Low Res

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