Albracht Presentation - 6th European Pole Vault and High Jump

21.03.2014
Achilles tendon forces during
human running
The role of tendon elasticity for
sports performance
Jun.-Prof. Kirsten Albracht
5 – 12 times
body weight
Institute of Biomechanics and Orthopaedics
German Sport University Cologne
[email protected]
Komi et al. 1992, J Sports Sci
Jumps with a run up
Sports performance
No series-elastic compliance in all MTUs
 26% maximum sprinting velocity
(Miller et al., 2012, J Biomech)
http://www.iaaf.org/about-iaaf/documents/research
No series-elastic compliance in the Achilles Tendon
 10% maximum walking velocity
Source of energy
(Sellers et al., 2010, Int J Primatol)
Material properties are important for tendon function
+
Muscle
COM
‚power amplification‘
‚energy conservation‘
modified from Roberts & Azizi, 2011, J Exp Biol
Energy conservation
stance
Touch down
Toe off
Muscle
Unit
Tendon
COM
‚energy conservation‘
http://www.oeb.harvard.edu/affiliates/cfs/movies/cfs_wallaby.avi
Energy storage
Biewener et al., J Exp Biol, 1998
Roberts & Azizi, J Exp Biol, 2011
Energy release
Biewener et al., J Exp Biol, 1998
Roberts & Azizi, J Exp Biol, 2011
1
distal
proximal
21.03.2014
Muscle pre-activation
Ultrasonography is used to study muscle and tendon behaviour of the GM
during human locomotion (e.g. Aggelousis et al., 2009, Fukunaga et al., 2001; Ishikawa et al.,
Muscle activation before ground contact regulates muscle stiffness and therefore energy storage in
the tendon (Gollhofer & Kyröläinen, 1991; Komi & Gollhofer, 1997; Ishikawa & Komi, 2004)
2005; Kawakami et al., 2002; Lichtwark et al., 2007; Spanjaard et al., 2007).
Energy conservation
knee
- Human running -
heel
Phase 1: COM Deceleration
Phase 2: COM Acceleration
0.50
change in length [ l0,fl ]
fascicle
MTU
0.25
0.00
-0.25
energy storage
energy release
-0.50
0
20
40
60
80
100
Stance [%]
Modified from Albracht & Arampatzis, Eur J Appl Physiol, 2013
Force and Power generation
Energy conservation
Phase 1: COM Deceleration
Leistung & Effizienz
- Muscle -
Phase 2: COM Acceleration
0.50
1.0
vMTU  6
l f ,0
s
Force/ Power
change in length [ l0,fl ]
fascicle
MTU
0.25
0.00
Power
0.05
Force
-0.25
energy storage
energy release
-0.50
0
20
40
60
Stance [%]
80
100
v f  1.5
l f ,0
s
 0.15vmax
Modified from Albracht & Arampatzis, Eur J Appl Physiol, 2013
Shortening velocity
1.0
Maximum
shortening
velocity
Adapted from A.V. Hill, 1938
2
21.03.2014
Over-challenging situation
Tendon function
120 %
Optimum
Drop Height
Optimum
Drop Height
 Force transmission
 Energy Storage & Release
SO
 Decoupling of the muscle from the entire muscle-tendon unit
GM
•
enable the muscle to work at a higher force potential due to the
force length and force velocity relationship
Drop jumps
Modified from Ishikawa & Komi, Exercise and Sport Science Reviews, 2008
Jumps with a run up
Power Amplifikation
- Squat Jump
= Work /
Time
http://www.iaaf.org/about-iaaf/documents/research
Source of energy
+
COM
‚energy conservation‘
‚Catapult effect‘
Muscle
‚power amplification‘
Modified from Roberts & Azizi, 2011, J Exp Biol
Roberts & Azizi, 2011, J Exp Biol
The catapult mechanism of frog jumping
1000
+
0
http://video.nationalgeographic.com/video/news/frogmuscle-study
Mechanical power (W)
+
-800
-100
0
Time (ms)
H. C. Astley & T. J. Robert, 2012
Roberts, T. J., Abbott, E. M. and Azizi, E. 2011
Data adapted from Kurokawa et al., 2001, J Appl Physiol
3
21.03.2014
Jumping performance
- Squat Jump -
1000
+
0
-
Mechanical power (W)
+
Muscle-Tendon-Unit Power
>
Muscle Power
~ 30%
-800
-100
0
Time (ms)
Bobbert 2001, J Biomech
Data adapted from Kurokawa et al., 2001, J Appl Physiol
Tendon function
Mechanical properties of the tendon
 Force transmission
- Effects of resistance training -
 Energy Storage & Release
 Decoupling of the muscle from the entire muscle-tendon unit
•
enable the muscle to work at a higher force potential due to the
force length and force velocity relationship
•
high power output due to a quick release of the stored energy
Tendon mechanical properties
Tendon mechanical properties
- Stiffness -
- Stiffness -
∆ 
Tendon stiffness (k): The extent to
which the tendon resists deformation
in response to an applied force
Force
Force
Force deformation relationship
∆ 
Legerlotz et al., 2007,
J Appl Physioll
=
∆ 
∆ 
Deformation
Deformation
4
21.03.2014
Tendon mechanical properties
Tendon mechanical properties
- Stiffness -
- Energy -
Tendon stiffness (k): The extent to which the tendon
resists deformation in response to an applied force
Stiff
tendon
∆ 
Force
∆ 
Force
∆ 
Less stiff
tendon
∆ 
=
Def
∆ 
∆ 
Deformation
Energy
Tendon mechanical properties
- Energy storage -
- Stiffness -
Force
Tendon mechanical properties
equal deformation
equal force level
Force
Force
Def
Raspanti et al., 2002
Def
Def
CSA
Length
Material
properties
Mechanical & morphological Properties of the Tendon
Mechanical & morphological Properties of the Tendon
- Effects of resistance training -
- Effects of resistance training -
Moment [Nm]
180
160
140
Stiffness [N/mm]
*
*
120
300
*
250
200
100
150
80
60
100
40
50
20
0
0
low
high
low
high
Isometric training, 14 weeks
Isometric resistance training, 14 weeks
Low: isometric 55% MWC/ 2.85±0.99% strain
High: isometric 90% MVC / 4.55±1.38%
Arampatzis, Karamanidis, Albracht., 2007, J. Exp. Biol
Data adapted from Arampatzis, Karamanidis, Albracht.,
2007, J. Exp. Biol
5
21.03.2014
Mechanical & morphological Properties of the Tendon
- Effects of resistance training -
Endurance running
Sprint running
High power
generation
High
economy
optimal muscle & tendon properties
?
 Tendon’s response to training is later than that of muscle
Kubo et al., Journal of Strength and Conditioning Research, 24 (2), 2010
Jumping performance
- DEPENDENCE OF HUMAN SQUAT JUMP PERFORMANCE
ON THE ACHILLES TENDON COMPLIANCE-
50
optimal
tendon mechanical
properties
jump height [cm]
45
Kenyan
40
35
30
Shank length [mm]
400 ± 20
430 ± 20
MG Fascicle length [mm]
54.2 ± 4.0
56.8 ± 9.4
MG tendon length [mm]
264 ± 25
196 ± 13*
+ 6 cm
25
0
5
10
15
maximum strain [%]
20
Sano K, et al.,
Eur J Appl Physiol, 2013
Data adapted from Bobbert 2001, J Biomech
Running economy
50
[Nm]
120
-1
100
80
150
60
100
40
50
20
0
0
-1
200
40
*
*
35
30
.
*
45
VO2 [ml min kg ]
*
250
pre
post
140
-1
300
pre
post
[kN strain ]
350
Caucasian control
group
25
5
0
max. moment
stiffness
3.0 ms
-1
3.5 ms
-1
exercise group
3.0 ms
-1
3.5 ms
-1
control group
14 week resistance training for the plantarflexors

sign. Increase in tendon stiffness (~15%) and muscle strength (~7%)
Albracht & Arampatzis, Eur J Appl Physiol, 2013

sign. better running economy: ~4.0 %, p < 0.002
Albracht & Arampatzis, Eur J Appl Physiol, 2013
6
21.03.2014
Conclusion
 Tendons material properties play an important role in athletic
performance (Bobbert 2001, J Biomech, Miller et al., 2012)
Thank you for your attention
 Tendons have the potential to adapt (CSA, material
properties)
 Tendons‘ response to training is later than that of muscle
(Kubo, 2008, J Theor Biol)
 Optimal tendon stiffness is task specific and depends on the
mechanical and morphological properties of the MTU
(Lichtwark & Wilson, 2008, J Theor Biol)
7