Hill-Type Muscle Models

Many studies of human movement (and rehabilitation) rely on Hill-type muscle models to evaluate motor performance based on non-invasive electromyographic (EMG) recordings of muscle function. These studies use activation features derived from EMG recordings to drive the force length (F-L) and force-velocity (F-V) properties of the muscles involved in a particular movement task.         
Together with James Wakeling's lab at Simon Fraser University, Research Associate Allison Arnold-Rife, postdoc Sabrina Lee (now at the Rehabilitation Institute of Chicago, Northwestern Univ.), we are conducting studies that seek to link in vivo and in situ validation of Hill-type muscle models based on animal studies to applications in human cycling performance. 

By combining in vivo methods for recording muscle activation (from indwelling EMG electrodes), muscle length changes via sonomicrometry and muscle-tendon force from tendon buckles:

Sonomicrometry    Muscle-tendon force buckles    Goat hind limb

GoatLG muscle model
We are developing novel muscle models that allow for differential recruitment of fast and slow motor units that can be validated against in vivo measures of muscle force and work output. Differential recruitment of the muscle is assessed by wavelet analysis. Our results show that a two-element muscle model gives improved predictive accuracy relative to standard models that assume uniform muscle activation, F-L and F-V properties.