The Effect of Different Turn Speeds on Whole-Body Coordination in Younger and Older Healthy Adults

Abstract

Difficulty in turning is prevalent in older adults and results in postural instability and risk of falling. Despite this, the mechanisms of turning problems have yet to be fully determined, and it is unclear if different speeds directly result in altered posture and turning characteristics. The aim of this study was to identify the effects of turning speeds on whole-body coordination and to explore if these can be used to help inform fall prevention programs in older adults. Forty-two participants (21 healthy older adults and 21 younger adults) completed standing turns on level ground. Inertial Measurement Units (XSENS) were used to measure turning kinematics and stepping characteristics. Participants were randomly tasked to turn 180° at one of three speeds; fast, moderate, or slow to the left and right. Two factors mixed model analysis of variance (MM ANOVA) with post hoc pairwise comparisons were performed to assess the two groups and three turning speeds. Significant interaction effects (p < 0.05) were seen in; reorientation onset latency of head, pelvis, and feet, peak segmental angular separation, and stepping characteristics (step frequency and step size), which all changed with increasing turn speed. Repeated measures ANOVA revealed the main effects of speeds within the older adults group on those variables as well as the younger adults group. Our results suggest that turning speeds result in altered whole-body coordination and stepping behavior in older adults, which use the same temporospatial sequence as younger adults. However, some characteristics differ significantly, e.g., onset latency of segments, peak head velocity, step frequency, and step size. Therefore, the assessment of turning speeds elucidates the exact temporospatial differences between older and younger healthy adults and may help to determine some of the issues that the older population face during turning, and ultimately the altered whole-body coordination, which lead to falls.

A Comparison of Turning Kinematics at Different Amplitudes during Standing Turns between Older and Younger Adults

“…All dependent variables were analyzed and extracted from MATLAB (R2020b) using a previously validated methodology [7,12,13]. A MATLAB (R2020b) program was used to analyze all measures from the kinematic datasets, using the following as dependent variables as follows;…”

“…1. The mean onset time of the head, trunk, pelvis and feet were defined as the yaw angular displacement and velocity profiles by selecting the time which corresponded to the rotation onset for each segment were amplitude greater than 0 • with a positive velocity [7]. In addition, the yaw angular displacement was defined as the angle of rotation onset for each segment in the yaw plane.…”

“…The peak segment angular separations were defined as the angle rotation subtracted between segments (the head and thorax and the head and pelvis), which were used as measures of axial segment and intersegment coordination. Although traditionally, a lack of differences in the timing of axial segment reorientation onset has been used to characterize turning as en-bloc, measuring the rotation of the head with respect to the lower body during the duration of the turn also gives a more complete description of which body segments lead which during the turning rotation [7]. 3.…”

“…The lack of planning for movement changes are associated with increase in age and with a decline in turning performance. Khobkhun et al (2021) [7] reported that changes in speed during turns over 180 • have a greater impact on segment onset latencies, intersegmental and stepping characteristics in older group compared to younger group. Furthermore, they reported that the upper and lower body move in an en-bloc strategy when turning at slower speeds in older adults, with the intersegmental angular separations in older adults being less than younger adults at faster speeds.…”

“…The authors concluded that their findings highlighted the importance of dynamic motion in the appropriate perception of spatial orientation. More recent studies have suggested monitoring of turning behavior using Inertial Measurement Units (IMUs) as a solution to assess gait, turning and balance in older adults [7,9,10], as these can be used outside of the laboratory setting. This current study used IMUs to assess the movements of different body segments which provided linear accelerations and Euler segment orientations during turning, which allows the exploration of the modulation of turn amplitude on turning characteristics and the spatiotemporal relationships between the body segments.…”