An Analytical Framework for Quantifying Muscular Action During Human Movement

A fundamental problem in human movement analyses is the quantification of individual, time- varying, muscle forces. Muscle forces not only play a major role in determining the stresses in bones and joints, but they also reflect the underlying neural control processes responsible for the observed movement patterns. Unfortunately, invasive techniques for measuring muscle forces are highly objectionable, whereas non-invasive techniques such as electromyography do not provide the quantitative accuracy needed to define muscle’s action on the skeleton. In addition, the human musculoskeletal system is mechanically redundant (i.e., the number of muscles spanning a joint exceeds the number of degrees of freedom defining joint motion) so that a direct solution of the muscle force-joint torque equations is not possible.