Kida, N. | Search bioRxiv

bioRxiv2023

Impact of body image on the kinematics of gait initiation

In our daily lives, we walk naturally because we can consider our physical characteristics and formulate appropriate motor plans. However, the impact of changes in body image during motor planning on walking movements remains poorly understood. Therefore, in this study, we investigated how walking movements change when body image is altered. We included 26 participants (13 males, 13 females, aged 18.27{+/-}0.52) to perform walking movements under five conditions: open eyes (baseline), closed eyes, closed eyes while imagining their bodies becoming large, closed eyes again, and open eyes again. As a result, under the condition where participants imagined their bodies becoming large, their stride length, step completion time, and foot lift height increased. These results are attributed to the disparity between actual body size and body image, which affects motor planning. The results of this study have potential applications in rehabilitation and sports coaching settings.

animal behavior and cognition↗

bioRxiv2023

Direction and distance dependency of reaching movements of lower limb

Efficient movement of the body is an important part of our daily lives, which we perform unconsciously. Such efficient movements have been investigated using reaching movements in the upper limb, and whose kinematics reportedly vary depending on the movement direction. However, the reaching movements of the lower limbs are not well understood. Therefore, we aimed to examine changes in the kinematics of the lower limb reaching movements to determine the mechanism of skilled motor ability in terms of direction and distance. Sixteen adults (10 males) were requested to reach targets projected on the floor in seven directions and at three distances, for a total of 21 points. We found that the reaching time slowed down for the contralateral side (right foot to left-sided target), and was caused by a slower start of the toe movement. To identify the cause of this delay, we analyzed the onset of movement at each joint and found that movement to the contralateral side began closer to the torso than movement to the ipsilateral side. The time-to-peak velocity was also calculated; the motion required to reach the target in the shortest time varied depending on the direction and distance. Acceleration phases that were not observed in the upper limb velocity profile were observed in the lower limb velocity profiles. These results suggest that movement kinematics vary with direction and distance, resulting in slower reaching time on the contralateral side.

animal behavior and cognition↗