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
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SPRINT ACCELERATION MECHANICS AND TRAINING
New technology, New concepts, New perspectives…
J-B Morin, PhD Laboratory of Exercise Physiology University of Saint-Etienne, France
« 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)
Sprint Acceleration Mechanics – Nov. 2013
Mea
n ve
rtic
al G
RF
(BW
)
6 to 12 m/s !
24 Men
9 Women Olympians
Only Vertical GRF is measured….and…
Sprint Acceleration Mechanics – Nov. 2013
3D Ground Reaction Forces, Speed, Power, 1000 Hz, step-averaged values…
Sprint Acceleration Mechanics – Nov. 2013
Sprint Acceleration Mechanics – Nov. 2013
Instantaneous
Average per step
2012
New&perspectives&!&
Sprint Acceleration Mechanics – Nov. 2013
Category: Coaching
2011,%new%concept…%
Sprint Acceleration Mechanics – Nov. 2013
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…
Sprint Acceleration Mechanics – Nov. 2013
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
Sprint Acceleration Mechanics – Nov. 2013
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 ?
Sprint Acceleration Mechanics – Nov. 2013
• 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)
Sprint Acceleration Mechanics – Nov. 2013
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
Sprint Acceleration Mechanics – Nov. 2013
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…)
Sprint Acceleration Mechanics – Nov. 2013
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
Sprint Acceleration Mechanics – Nov. 2013
• 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)
Sprint Acceleration Mechanics – Nov. 2013
Main results…
Confirms our previous results ! How the resultant force is applied is more important than its magnitude
2011
Sprint Acceleration Mechanics – Nov. 2013
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…
Sprint Acceleration Mechanics – Nov. 2013
WCS
The higher the speed, the larger the difference in RF….
Question: How can we produce high HZT force AT HIGH SPEED ???
Sprint Acceleration Mechanics – Nov. 2013
Synchronized EMG and 3D Forces Sprint and repeated sprint (fatigue)
! Partnerships (football, basketball, rugby, tennis, athletics) ! First long-term follow-ups initiated all over the world ! Experiments: Training vs. Control Groups…
Sprint Acceleration Mechanics – Nov. 2013
FORCE – VELOCITY - POWER
What!about!SPRINT!RUNNING!???!
Sprint Acceleration Mechanics – Nov. 2013
Sprint performance analysis…
« Speed-time curves » ! 1927, Archibald HILL, pioneer
What could be possible with field devices?
RADAR, GPS, Photocells, iPhone ??
Sprint Acceleration Mechanics – Nov. 2013
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….
Sprint Acceleration Mechanics – Nov. 2013
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