Modelling the functional heterogeneity of skeletal muscles : enriching continuum-mechanical models on a motor-unit level

Abstract

Biomechanical computer models provide novel insights into musculoskeletal function by overcoming technical and ethical barriers faced by experimental techniques. Current macroscopic, continuum-mechanical skeletal muscle models, however, neglect certain aspects of motor-unit physiology and thus oversimplify muscle function. This Ph.D. thesis deals with methods to enrich such models with microstructurally derived motor-unit information. By doing so, contraction dynamics and joint-kinematics can be predicted, for the first time, as a combination of individual motor-unit -activity, -properties, and (three-dimensional) -anatomy. Such a model uncovers unique relationships between neuromuscular physiology and muscle function, for example, the role of motor-unit remodelling (typically occurring during ageing and neuromuscular disorders) on joint-function. This integrated neuro-musculoskeletal modelling approach can be applied to better understand phenomena such as fatigue and be used to inform medical interventions by predicting surgery outcomes or aiding movement rehabilitation protocols related to trauma, neuromuscular disorders, or ageing.