Human muscle modelling from a user's perspective.
Methods for developing mathematical models representing entire human muscles are briefly reviewed, with special emphasis on aspects of modelling velocity dependence using cross-bridge dynamics, and isometric force-length properties from myofilament lengths and muscle architecture. For each of these components, mechanistic (using basic contraction mechanisms) and phenomenological ("black-box") models are available. Experiments on constant-velocity lengthening at different velocities were simulated using (a) a cross-bridge based model and (b) a Hill-based model. The Hill model was superior in its ability to predict muscle forces under different conditions with the same model parameters. Regarding force-length properties, myofilament overlap and muscle architecture did not correctly predict maximal isometric joint moments over the entire functional range of motion. The width of the force-length relationship of all contractile elements in a lower extremity model may be optimized to fit measured isometric moment-angle relationships. The resulting increase in width suggests that for some short-fibered muscles with complex architecture, the "effective" muscle fibre length is increased because muscle fibres may be partly connected in series as well as in parallel. It is concluded that a hybrid phenomenological/mechanistic muscle model is most likely to be practical (i.e. parameters can be estimated for human muscle) as well as accurate (i.e. correct forces are predicted for a wide range of conditions.
van den Bogert
A J
AJ
Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Canada. bogert@acs.ucalgary.ca
Gerritsen
K G
KG
Cole
G K
GK
D008841:Actin Cytoskeleton / Q000502:physiology / Q000648:ultrastructure; D001696:Biomechanical Phenomena; D005544:Forecasting; D006801:Humans; D007537:Isometric Contraction; D007596:Joints / Q000502:physiology; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000502:physiology / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D009210:Myofibrils / Q000502:physiology / Q000648:ultrastructure; D016059:Range of Motion, Articular / Q000502:physiology; D013314:Stress, Mechanical