Mechanical energy of the trunk during walking--does the model used influence the results?

The paper presents two trunk models. In the first one, the trunk is modelled as a series of seven segments, whose dimensions and inertial properties are parametrically based on body stature and body mass. In the second one, the trunk is modelled as one rigid segment. These models are used to calculate kinetic energy of the trunk relative movement with respect to the body centre of mass. The results show that in the case of healthy subject both models give similar results, but in the case of stroke subjects the simplified model leads to the underestimation of the energy amount and does not reflect all phases of gait when energy is generated.