KINEMATIC CONTROL IN ACTIVE ACCELERATION AND ADJUSTMENT OF GAIT SPEED

T. Kokue¹, Y. Takenaka², K. Sugawara³

¹Kanagawa University of Human Services, Master’s Course, Yokosuka, Japan, ²Kanagawa University of Human Services, Ph.D. Course, Yokosuka, Japan, ³Kanagawa University of Human Services, Physical Therapy, Yokosuka, Japan

Background: In daily life, people rarely walk at a constant speed but actively adjust their gait speed according to their purpose and environment, making it necessary to examine gait speed adjustment. However, to the best of our knowledge, no studies have analyzed kinematic factors during active variable adjustment of gait speed.

Purpose: This study aimed to clarify kinematic control during walking using a task that actively adjusted the acceleration of gait speed.

Methods: The participants were nine healthy young adults. A three-axis accelerometer was used to measure trunk stability during walking. The center of gravity acceleration was recorded by the three-axis accelerometer during walking, and the root mean square (RMS) of each axis (RMSx, RMSy, and RMSz) was calculated for every step. Walking speed was recorded for every step using the Optjump Next according to the lower limb ground contact position recorded by the infrared sensor. First, the participants performed a constant-speed walking task, either at a comfortable or maximum walking speed, three times each.
Next, the participants were given time to learn the intermediate walking speed, calculated as the speed between the comfortable and maximum walking speeds. Subsequently, two acceleration conditions were enforced. Participants walked at a comfortable walking speed and switched to either the maximum ("comfortable-maximum" condition) or intermediate ("comfortable-intermediate" condition) walking speed as quickly as possible using a randomly timed sound output from a speaker as a cue. Five trials were conducted for each task. For statistical analysis, analysis of variance with a linear mixed model was performed on each measured item, with the walking condition and number of steps as fixed effects and the subjects as random effects. The significance level for all tests was set at 5%.

Results: The study revealed significant interactions and main effects for walking speed, RMSx, and RMSy and only significant main effects for RMSz.
There was a significant increase in walking speed immediately after the cue sound in both conditions, when compared with a comfortable walking speed. There was a significant increase in walking speed immediately after the cue sound in the comfortable-maximum condition compared with that in the comfortable-intermediate condition.
In the RMS of each axis, there was a significant increase in the comfortable-maximum condition compared with the comfortable-intermediate condition from the first step after the cue sound. RMSx and RMSy increased significantly from the first step in the comfortable-maximum condition, when compared with a comfortable walking speed.

Conclusions: The results of this study revealed kinematic control in active acceleration and adjustment of walking speed, which was especially true for RMSx and RMSy. Consequently, acquiring the ability to flexibly control various walking speeds is important, depending on the target walking speed.

Implications: We believe that the results of this study are important for planning walking tasks that are more suited to daily life than conventional walking tasks.

Funding acknowledgements: This work was supported by JSPS KAKENHI (Grant Number 20K11287).

Keywords:
Walking speed adjustment
acceleration
three-axis accelerometer

Topics:
Health promotion & wellbeing/healthy ageing/physical activity
Older people

Did this work require ethics approval? Yes

Institution: Kanagawa University of Human Services

Committee: Office of Research Ethics at Kanagawa University of Human Services

Ethics number: No. 7-20-67