ABSTRACT
This chapter is intended to provide an understanding of how the forces in the musculoskeletal system can be estimated. After reading this chapter you should be able to:
• calculate the joint contact and muscle forces for single segment, single muscle, planar motions
• understand and evaluate simplifications made in ‘inverse dynamics modelling’
• explain the terms in the equations for calculating joint reaction forces and moments for single segments, and for a segment chain, in planar motions
• understand how multiple-segment systems can be analysed to calculate joint reaction forces and moments
• appreciate the difficulties of calculating the forces in muscles and ligaments arising from the indeterminacy (or redundancy) problem (too few equations to solve for the number of unknowns)
• describe and compare the various approaches to solving the indeterminacy problem
• understand the method of inverse optimisation, and evaluate the various cost functions used
• appreciate the uses and limitations of electromyography (EMG) in estimating muscle force
• outline an example of muscle force calculations during a sports injury and the difficulties and limitations that exist even when this information is available.
