Gastrocnemius Muscle Fascicle Behavior Explored With a 3D Muscle Model

The gastrocnemius muscles are important for support and forward progression of movement [1], and they are commonly impaired in neurological disorders, such as stroke and cerebral palsy [2]. Currently, lumped-parameter representations [3] are used to model the gastrocnemius muscles in simulations of human movement. These representations simplify muscle architecture by assuming that all fibers are the same length, that aponeuroses behave as if they are in series with muscle fibers, and that fibers have a simple geometric arrangement. Previous studies have suggested that these simplifications may result in an overestimation of fiber length changes during movement and therefore predict that too much variation in force with joint angle (e.g., [4]).