ASPECTS OF THE ENERGETICS AND THE MECHANICS OF HUMAN LOCOMOTION

Abstract

The relationship between the mechanical work performed by the muscles during locomotion and the corresponding metabolic energy consumption is still not completely understood beside the methodological problems and the inherent assumptions in the calculation of both mechanical work and metabolic energy it seems that many factors can affect this relationship. They can be of very different nature depending on muscle structure and composition, body dimension. kinetic and kinematic parameters. The analysis of the mechanical work, in terms of its two component, external work !that done to lift and to accelerate the centre of mass at each step) and internal work (that of accelerating the limbs relative to the body centre of mass), together with the measurement of the metabolic energy consumption, appears a useful approach to better understand the determinants of many characteristics of human locomotion. The relevance of the external and of the internal work has been inferred by altering them separately in particular conditions as in uphill and downhill walking and running or in loaded locomotion (adding 'weight to the trunk or to the limbs).Optimization processes that seem to set the normal speed of walking of unrestrained subjects, the speed of spontaneous transition from walking to running. the frequency freely adopted at a given gait and speed seem better explained on these bases Yet, from the results so far obtained, it appears that neither mechanical work and energy cost are the sole determinants of many aspects of human locomotion.