###### Abstract  
It is well-established that processes involving changing direction or turning in which either or both standing and walking turns are utilized involve coordination of the whole-body and stepping characteristics. However, the turn context and whole-body coordination have not been fully explored during different turning amplitudes. For these reasons, this present study aimed to determine the effects of turning amplitude on whole-body coordination. The findings from this study can be utilized to inform the rationale behind fall prevention factors and to help design an exercise strategy to address issues related to amplitude of turning in older adults. Twenty healthy older and twenty healthy younger adults were asked to complete standing turns on level ground using three randomly selected amplitudes, 90\({}^{\circ}\), 135\({}^{\circ}\) and 180\({}^{\circ}\), at their self-selected turn speed. Turning kinematics and stepping variables were recorded using Inertial Measurement Units. Analysis of the data was carried out using Mixed Model Analysis of Variance with two factors (2 groups \(\times\) 3 turning amplitudes) and further post hoc pairwise analysis to examine differences between factors. There were significant interaction effects (\(p<\) 0.05) between the groups and turning amplitudes for step duration and turn speed. Further analysis using Repeated Measure Analysis of Variance tests determined a main effect of amplitude on step duration and turn speed within each group. Furthermore, post hoc pairwise comparisons revealed that the step duration and turn speed increased significantly (\(p<\) 0.001) with all increases in turning amplitude in both groups. In addition, significant main effects for group and amplitudes were seen for onset latency of movement for the head, thorax, pelvis, and feet, and for peak head-thorax and peak head-pelvis angular separations and stepping characteristics, which all increased with turn amplitude and showed differences between groups. These results suggest that large amplitude turns result in a change in turning and stepping kinematics. Therefore, when assessing the turning characteristics of older adults or those in frail populations, the turning amplitude should be taken into account during turning, and could be gradually increased to challenge motor control as part of exercise falls prevention strategies. t +
Footnote †: journal: 28 May 2022  
to age, previous research has indicated that sex has an impact on both postural stability, balance and gait speed; that is, males walk faster than women, which is generally ascribed to the longer step and stride length produced by men [5, 6]. However, there have been no reports of the differences between the sexes in turning tasks. Furthermore, turning situations associated with daily activities frequently involve hasty and unpredictable movements with limited time for planning. The lack of planning for movement changes are associated with increase in age and with a decline in turning performance. [PERSON] et al. (2021) [7] reported that changes in speed during turns over 180\({}^{\circ}\) 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. These findings have been previously linked to a shorter stride length and potentially, but not exclusively, to a slower gait speed which may be the consequence of an intentional reduction in turning strategy to compensate for perceived postural instability, which may in turn increase the risk of falling in older adults.