european weightlifting federation coaches...

- Biomechanics @University of Rome "Tor Vergata", Faculty of Medicine and Surgery, School of Sports and Exercise Sciences

- Research&Development @Newsens S.r.l. , Rome - Italy

European Weightlifting Federation Coaches Forum

Olympic Preparation Centre - Rome, 18th January 2014

Muscle strength assessment during resistance training exercises:

sensing weights kinematics using inertial sensors

Pietro Picerno, PhD

([email protected])

EWF Coaches Forum Pietro Picerno Muscle strength assessment in resistance training exercises

Muscle s t rength: leve ls of observat ion


Level 1 : assessing muscle tension


0

45

90

135

180

0

500

1000

1500

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0.01 0.16 0.31 0.46

Kn

ee

fle

xio

n [d

eg]

Forc

e [N

]

Time [s]

Ground Reaction Force

FZ

FX

FY

FZ

FX

FY

Level 2 : assessing ef fects of muscle tension

GRF

Knee flexion

squat with 20kg @max velocity(80kg subject’s mass)


0

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0

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0.01 0.16 0.31 0.46

Kn

ee

fle

xio

n [d

eg]

Forc

e [N

]

Time [s]


FZ

FX

FY

FZ

FX

FY


GRF

Knee flexion


(msubject+mbarbell)·g

STATIC

MOTION

(msubject+mbarbell)·(g+a)

external acceleration of the body is added(effect of muscles action)


0

45

90

135

180

0

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0.01 0.16 0.31 0.46

Kn

ee

fle

xio

n [d

eg]

Forc

e [N

]

Time [s]


FZ

FX

FY

FZ

FX

FY


GRF

Knee flexion


(msubject+mbarbell)·g

STATIC

MOTION

(msubject+mbarbell)·(g+a)

external acceleration of the body is added(effect of muscles action)

Lifting 1RM : external acceleration close to zero


FZ

FX

FY

FZ

FX

FY



-10

-5

0

5

10

15

20

0.01 0.16 0.31 0.46

Acc

ele

rati

on

[m/s

^2]

Time [s]

CoM acceleration

0

45

90

135

180

0

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0.01 0.16 0.31 0.46

Kn

ee

fle

xio

n [d

eg]

Forc

e [N

]

Time [s]


body acc = (GRF/mtot)-g


FZ

FX

FY

FZ

FX

FY



-10

-5

0

5

10

15

20

0.01 0.16 0.31 0.46

Acc

ele

rati

on

[m/s

^2]

Time [s]

CoM acceleration

0

45

90

135

180

0

500

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1500

2000

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3000

0.01 0.16 0.31 0.46

Kn

ee

fle

xio

n [d

eg]

Forc

e [N

]

Time [s]

Ground Reaction Force• quadriceps contrats and shortens

• while shortening, it pulls the leg which rotates (knee extension)

• since ground does not warp, this rotation cause the feet pushing the ground

• ground replies with the same (inverted) force (GRF)

• GRF accelerates the body/barbell upwards


-1

-0.5

0

0.5

1

1.5

2

0.01 0.16 0.31 0.46

Load

[g]

Time [s]

Load (1g = BW)

FZ

FX

FY

FZ

FX

FY



-10

-5

0

5

10

15

20

0.01 0.16 0.31 0.46

Acc

ele

rati

on

[m/s

^2]

Time [s]

CoM acceleration

“Load” = body acc/g


-1

-0.5

0

0.5

1

1.5

2

0.01 0.16 0.31 0.46

Load

[g]

Time [s]

Load (1g = BW)

FZ

FX

FY

FZ

FX

FY

-10

-5

0

5

10

15

20

0.01 0.16 0.31 0.46

Acc

ele

rati

on

[m/s

^2]

Time [s]

CoM acceleration

Level 3 : neuromuscular character izat ion

FORCE CLASSIFICATION (Bosco):

• amount of weight

• speed of force application

Fmax = 1.7 BW

RFD


Alternat ives: measur ing barbel l k inemat ics

BARBELL DISPLACEMENT (cameras)

software:Kinovea



BARBELL DISPLACEMENT (wire draw encoders)

software:Ergopower (Ergotest Techn, Norway)Ergosystem (Glubus Corp., Italy)Smartcoach (Smartcoach, Sweden)


Too many wires around…


Evolut ion of technology



BARBELL ACCELERATION(inertial sensors)

Rugby Rovigo - Italy


Tri-axial gyroscopeTri-axial accelerometer

• small

• low power consumption

Integrated system

Bluetooth®

Evolut ion of technology


Iner t ia l sensors: pr inc ip le of funct ioning


Inner ear


Iner t ia l sensors

• triaxial accelerometer

(measure of linear accelerations along the geometrical axes of the device)

• triaxial gyroscope

(measure of angular velocities about the xes of the device)

z

y

x


Why gyroscopes?

accelerometer’s axis alignedwith weight’s direction

za

g

az- g

za

g

a

za

gaz- gcosa

accelerometer’s axis continuously rotates


From accelerat ion back to ve loc i ty

acceleration

velocity

v = v0 + a(t-t0)

Concentric phase [s]


Barbel l ’s accelera t ion and ve loc i ty

-600

-400

-200

0

200

400

600

800

0 0.25 0.5 0.75 1 1.25

Tempo [s]

Velocity [cm/s]Force [N] Power [W]

b e n c h p re s s @ 2 0 k g ( e c c - c o n c )L av o ro c o n s o v ra c c a r i c h i ( i s o i n e r z i a l e )

Time [s]


Barbel l ’s accelera t ion and ve loc i ty

-1000

-500

0

500

1000

1500

0 0.25 0.5 0.75 1 1.25

Po

ten

za [

W]

Tempo [s]

@ 40 kg@20 kg @ 60 kg

b e n c h p re s s ( e c c - c o n c )

Time [s]

Po

we

r [W

]


W h i c h v a l u e s h o u l d w e u s e t o r e p r e s e n t t h e e x p r e s s i o n o fm u s c l e p o w e r d u r i n g e a c h s i n g l e r e p e t i t i o n ?

-200

0

200

400

600

800

1000

1200

1400

0.63 0.64 0.65 0.66 0.67 0.68 0.69 0.70 0.71 0.72 0.73 0.74 0.75

Po

ten

za [

W]

Tempo [s]

peak value

mean value

Assessing muscle power

Time [s]

Po

we

r [W

]


S i n c e t h e m e c h a n i c a l a d v a n t a g e o f m u s c l e s c h a c h e s w i t hR o M …

-200

0

200

400

600

800

1000

1200

1400

0.63 0.64 0.65 0.66 0.67 0.68 0.69 0.70 0.71 0.72 0.73 0.74 0.75

Po

ten

za [

W]

Tempo [s]

mean value

Assessing muscle power

Time [s]

Po

we

r [W

]


Muscular prof i le

software: FreePower (Newsens S.r.l., Italy)


Real t ime targeted t ra in ing

Power exerted during 6 repetitions @ bench-press with real-time biofeedback monitoring



Power exerted during 6 repetitions @ bench-press with real-time biofeedback monitoring





Aldo Montano (fencing) training with FreePower


FIPE one

A simple real time muscle power monitor for strength training and assessment


wired instrumentation


The beginning of the wi re less…

european weightlifting federation coaches...

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