Bending moments in lower extremity bones for two standing postures.

Faculty of Electrical and Computer Engineering, University of Ljubljana, Slovenia.

The goal of this paper is to study how external gravitational forces stress the lower extremity bones and to ascertain and study how muscle activation compensates for the external load. For these purposes relatively accurate anatomical and biomechanical modelling is necessary. For a comparison of the calculated results to the naturally occurring muscular activity, seven-channel surface EMG activity was recorded. For simplicity a two-dimensional model was developed for the sagittal plane including 19 lower extremity muscles relevant to human standing and walking. In the calculation procedure of muscle forces an optimization procedure is also included. The results give rise to the expected assumption that muscle action is covered by two main requirements: first, to stabilize the joint actively (moment equilibrium) and, second, to compensate efficiently for bending moments produced by gravitational and external forces.

PMID: 1513134 [PubMed - indexed for MEDLINE]