Gait asymmetry

The sum of scores of UPDRS III items 20 to 26 was used to determine the clinically more affected side (MAS) and the opposite less affected side (less affected side: LAS). These items refer to rest tremor, action or postural tremor, rigidity, finger taps, hand movements, rapid alternating movements of the hands, and leg agility, respectively. The MAS is defined by higher scores in these items. Footedness was assessed by asking all participants to kick a ball to hit a target. The limb that each individual chose to kick the ball was considered the dominant limb (DL). The asymmetry between the MAS and LAS for people with PD and the DL and non-dominant limb (NDL) for the control group was analyzed using an Asymmetry Index (A_i)^16,17:

An index value of zero indicates that there is no asymmetry. To calculate the A_i, first, we calculated the average of each obstacle crossing parameter for each lower limb. Next, the A_i for each participant was calculated according to gait conditions. In walking with obstacles, each lower limb performs a specific role (leading and trailing limb), and, thus, the A_i was performed between corresponding steps (i.e., right and left leading limb – Fig. 2).