Three-dimensional muscle force prediction during gait

One of the problems in modelling musculo-skeletal systems is the dimensional size of the muscular subsystem. This dimensional size can be decreased, either by neglecting specific muscle behavior or by reducing the number of planes of motion. However, these assumptions will strongly affect the outcome of predicted muscle forces and activations. Both reduction techniques are used and compared with each other. Including the muscle dynamics, the calculated muscle forces are more smoothed and are active over a longer period of time, as shown by the increase of the mechanical work. This increase is caused by more synergistic and antagonistic muscle actions, While increasing the number of motion planes, the total amount of mechanical work by the muscles does not significantly change. However, the total amount of metabolic energy consumption does increase.