Assessment of spatio-temporal parameters during unconstrained walking.

This paper presents an analysis of spatio-temporal gait parameters during overground walking based upon a method that needs only lower trunk accelerations. Twenty-six healthy young subjects and 15 healthy elderly subjects participated in an experiment where overground walking was studied at different speeds. Accelerations of the lower trunk were measured by a tri-axial accelerometer connected to a portable data logger carried on the body. An analysis of trunk acceleration data produced temporal gait parameters (duration of subsequent stride cycles and left/right steps) and convincing estimations of spatial parameters (step length and walking speed). Typical differences in spatio-temporal gait parameters between young and elderly subjects could be demonstrated, i.e. a limited range of walking speeds, smaller step lengths, and a somewhat higher variability of temporal parameters in elderly subjects. It is concluded from these results that essential spatio-temporal gait parameters can be determined during overground walking using only one tri-axial accelerometer. The method is easy-to-use and does not interfere with regular walking patterns. Both the accelerometer and the data logger can be miniaturised to one small instrument that can be carried on the trunk during hours of walking. Thus, the method can easily be incorporated in current activity monitors so that 24-h monitoring of postures and activities can be combined with assessment of gait characteristics during these monitoring periods. In addition, the presented method can be a basis for more sophisticated gait analyses during overground walking, e.g. an analysis of kinematic signals or muscle activity within subsequent stride cycles.