Predicting stride time variability in healthy italian adults: examining variabilities of individual motor inputs and outputs

High stride time variability, the integrated motor output of the locomotor system, is a factor in age-related falls. The origin of this variability remains unclear, but likely originates from variability of the motor inputs and outputs from individual muscles and joints. The gait of Italian males and females aged 19-99 years was analyzed using EMG and optoelectronic cameras. Variability parameters of motor inputs (EMG amplitudes) and motor outputs (joint angles) were extracted, parameters were reduced in principal component analyses, and regression models assessed which components predicted stride time variability in gait. A total of 10 principal components explained the majority of variance in motor input and motor output variability. Two of these components, interpreted as the variability of ankle plantar flexion and ankle dorsiflexion, independently predicted stride time variability. This suggests that reducing ankle motor output variability may help reduce excessive stride time variability and help prevent falls.