An energy 'sources' and 'fractions' approach to the mechanical energy expenditure problem--IV. Criticism of the concept of 'energy transfers within and between links'

The methods of evaluation of mechanical energy economy during human movement based on the calculation of three different values of work (Wwb, Ww, Wn), corresponding to three hypothetical types of energy exchange, are subject to criticism. Only the value of work, Wwb, calculated under the assumption of energy transfers between links and energy transformations within links, can be useful as the lowest limit of mechanical energy expenditure (MEE) for the control (for the cases when the powers of the external sources are equal to zero). In the particular case when all of the joint powers Mi,i+1 (phi i+1 -phi i) have the same signs and all sources of external energy are absent, Wwb equals the MEE for the control.