Fig. 7.

Variation in aponeurosis stiffness with biaxial loading. (A) A schematic of aponeurosis behavior during active and passive force production. (B) The longitudinal stiffness of aponeuroses (along the muscle line of action) as a function of transverse strain. L₀ is the resting length of the aponeurosis. When the tissue is loaded biaxially during active force production the effective longitudinal stiffness of the elastic structure increases. This figure highlights the capacity of aponeuroses to function across range of stiffnesses dynamically (modified from Azizi and Roberts, 2009).