Kinematics of Walking in Humans

A history is given of the experimental techniques used in gait analysis. There follows a description of the phasic activity of various musculo-skeletal elements of lower limbs during a step of normal walking. Equations are derived, relating the output signals of accelerometers, fixed to a moving body, to the motion of that body. Methods of solution to these equations are given, taking into account various approximations and simplifications. A suitable form is suggested for an accelerometric measurement system for studying the movement of the shank. Computer programs, which analyse the signals from such a system, are explained. The following variables are found as functions of time: translational acceleration, angular and translational velocity, and angular and translational displacement. Those features of the above variables which are characteristic of certain types of gait are discussed. The clinical usefulness of a selection of these variables is also examined. The development of a tape-recorder for use with the accelerometers is explained. It is concluded that accelerometry is a useful technique for the study of human body movement.