Experiments on Man, Loaded and Unloaded

The classical researches of Weber and Weber1 on the mechanics of human gait have demonstrated that the movements of man, particularly in walking and running, are amenable to mechanical processing. This is based on the possibility of obtaining accurate knowledge of a particular movement by direct measurement. The results, empirically obtained, constitute the foundation for subsequent studies. One has to deal with a mechanical problem: from the movements carried out by the different parts of the human body the forces necessary to cause those movements have to be deduced. This problem can in principle always be solved if one understands the process of movement and if one knows the magnitude of the mass, the position of the centre of gravity, the magnitude of the moments of inertia of each part of the body and in what way the movements of the different parts of the body are conditioned by articulation and external forces such as friction against the ground. Conversely, difficulties very often oppose the precise solution of the reverse problem, that is to deduce the movements from a knowledge of the forces.