Identifying the Effects of Age and Speed on Whole-Body Gait Symmetry by Using a Single Wearable Sensor.

Studies on gait symmetry in healthy population have mainly been focused on small range of age categories, neglecting Teenagers (13-18 years old) and Middle-Aged persons (51-60 years old). Moreover, age-related effects on gait symmetry were found only when the symmetry evaluation was based on whole-body acceleration than on spatiotemporal parameters of the gait cycle. Here, we provide a more comprehensive analysis of this issue, using a Symmetry Index (SI) based on whole-body acceleration recorded on individuals aged 6 to 84 years old. Participants wore a single inertial sensor placed on the lower back and walked for 10 m at comfortable, slow and fast speeds. The SI was computed using the coefficient of correlation of whole-body acceleration measured at right and left gait cycles. Young Adults (19-35 years old) and Adults (36-50 years old) showed stable SI over the three speed conditions, while Children (6-12 years old), Teenagers (13-18 years old), Middle-Aged persons and Elderly (61-70 and 71-84 years old) exhibited lower SI values when walking at fast speed. Overall, this study confirms that whole-body gait symmetry is lower in Children and in Elderly persons over 60 years of age, showing, for the first time, that asymmetries appear also during teenage period and in Middle-Aged persons (51-60 years old).