Improvements within the A.V. Hill model structure: strengths and limitations

An assessment is made of the strengths and weaknesses of Hill-based muscle models, in particular as compared on purely mechanical grounds to more complex kinetic models. It is seen that the Hill model in its basic form is adequate for a wide variety of movement tasks but on the surface appears to fail in a few specific situations. A number of extensions are proposed that essentially remedy these problems, the primary one being the addition of a yielding effect produced by making the input to the contractile element dependent on recent mechanical history. This modified model displays the capacity to simulate history-dependent muscle behaviors not previously possible with Hill-based models while keeping relations for the mechanical machinery intact.<>