Figure 3.

Deformed (active) and undeformed (relaxed) geometries for (A) the Uniform activation pattern and (B) the proximal-distal activation pattern. These geometries are shown with pale areas and blue lines for the undeformed states, and darker areas and gray lines for the deformed states. Note that in the deformed states the pennation angle for the proximal-distal activation pattern (18.37°) is larger than for the Uniform activation pattern. Transverse sections through the muscles are shown for the (C) Midline activation pattern, and (D) Medial-lateral activation pattern. In these panels the undeformed shape is shown by the rectangular and dark red area. The colored elements show the magnitude of the strain in the model tissues in their deformed state, ranging from low strains (blue) in the aponeurosis to greatest strains (red) in the muscle belly. Note how the muscle belly thickness between the aponeuroses is least over the active region of fibers, and the width of the muscles has increased beyond the undeformed state. Also note that in the Medial-lateral activation pattern the maximum strains have moved laterally (to the left) within the muscle.