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20
DIMS årsmøde
A2
THE EFFECT OF TRAINING ON ACHILLES APONEUROSIS PROPER-
TIES
Sofie Rosager, Per Aagaard, Michael Kjaer, S Peter Magnusson
Team Danmark Test Center/Sports Medicine Research Unit, Bispebjerg Hospital,
Copenhagen
INTRODUCTION: We measured the load-displacement and stress-strain
characteristics of the human triceps surae aponeurosis and tendon, in vivo,
during voluntary plantarflexion, in trained (n=7) and control (n=8) subjects.
METHODS: During a 10-s ramp isometric maximal plantarflexion simultaneous
and synchronous measures of real-time ultrasonography of aponeurosis
displacement, EMG of the gastrocnemius, soleus, and tibialis anterior
muscles, and joint angular motion were obtained. MRI was used to estimate
tendon CSA and moment arm. Force and EMG data from maximal isometric
dorsiflexion efforts were used to examine the effect of coactivity on the
mechanical properties. Tendon force was calculated from the measured joint
moment and tendon moment arm, and stress was obtained by dividing it
with CSA. Tendon strain was obtained from displacements normalized to
tendon length, and subsequently stiffness and Young’s modulus were calculated.
RESULTS: (meansem).
CSA,mm 2 Force N Displ, mm Strain, % Stress, MPa
Runner 925 2114456 8.71.6 3.60.7 224
Control 784 2095330 9.41.2 4.20.8 297
The stiffness was 40085 N/mm for controls and 28146 N/mm for runners.
The modulus was 74390 MPa for runners and 1131224 Mpa for controls.
Controls only differed from runners in CSA, P