Illustration of method used to estimate the fascicle length and pennation angle.

<p>The proximal and distal ends of the superficial aponeurosis, deep aponeurosis, and muscle fascicle were tracked automatically at each frame. The missing part was estimated by linear interpolation.</p

Illustration of method used to estimate Subject-Specific Tendon-Aponeurosis.

<p>(A) Geometric model of the muscle-tendon-aponeurosis complex that includes fascicle, tendon, and aponeurosis adapted from Fukashiro et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044406#pone.0044406-Fukashiro1" target="_blank">[23]</a>. The aponeurosis length is: _. Hill-type muscle model with the tendon and the aponeurosis in series (B) and a resulting Tendon-Aponeurosis element representing the tendon and aponeurosis in series (C).</p

Decoupling behaviour between muscle fibre and muscle-tendon unit.

<p>Comparison of the velocity of the muscle fibre, the tendon-aponeurosis unit and the muscle-tendon unit from one subject on running tasks for the (A) generic and (B) SS T-A conditions and from (C) a previous experimentation with the muscle fibre velocity measured using ultrasonography. Note that the SS T-A condition leads to physiologically sound behaviour of the muscle fibre while the generic condition simply shared the muscle-tendon stretch over both the fibre and the SEE complex. Reprinted with permission.</p

Description of EMG-driven model (A) Calibration and (B) Prediction process of the EMG-driven model.

<p>(1) represents the Anatomical Model used to estimate muscle-tendon lengths and moment arms, (2) an EMG-to-Activation Model to represent muscle activation dynamics, (3) a Hill-type Model to characterize muscle-tendon contraction dynamics and estimate the forces in the muscle-tendon complex, (4) a calibration process to tune model parameters based on ankle net joint moment computed by Inverse Dynamic, and (5) a prediction process to predict joint moment by using adjusted model parameters.</p

Summary of the behaviour of the muscle fibre and the tendon-aponeurosis unit in terms of variation of length and velocity.

*<p>Significative difference between SS T-A and Generic.</p

Estimation of Tendon-Aponeurosis force-strain relationship from tendon and aponeurosis individual force-strain relationship.

<p>At the same force level, the tendon and aponeurosis strain were estimated and combined with an experimentally-derived ratio to compute the Tendon-Aponeurosis strain (see eq. 5 in text).</p

Comparison of maximal muscle force: SS T-A vs. Generic.

<p>Mean maximal force estimated by the EMG-driven model according to the condition, SS T-A and Generic for the GL (A), GM (B), SOL (C) and the <i>Triceps Surae</i> group (i.e., sum of GL, GM, and Sol muscles) (D). * indicates a significant difference between the conditions (SS T-A vs. Generic).</p

Summary of muscle-tendon geometric parameters estimated by US in rest position or from Maganaris et al. [6] and used to estimate the muscle specific tendon-aponeurosis force-strain relationships.

†<p>represent the value used from Maganaris et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044406#pone.0044406-Maganaris1" target="_blank">[6]</a>.</p

Normalized fibre length and velocity with corresponding muscle forces for the <i>soleus</i>.

<p>Trajectory of normalized fibre length and velocity for one subject corresponding to the <i>soleus</i>. The colours of the curve represent the different part of the force-length and force-velocity relationships cover by the normalized fibre length and velocity according to the SEE definition. The figure at the bottom represents the muscle forces according to the SEE definition.</p

Example of input and output data of an EMG-driven model.

<p>Example of input data (Normalized EMG, muscle-tendon lengths and moment-arms) and output data (muscle forces and net ankle joint moment) for one subject during the contact phase of a hopping trial. The output data were obtained for both SEE definitions: the SS T-A and the generic.</p