Variability of Circular Leg Movements Is Related to Footedness and Postural Stability.

The control of the lower limbs is essential to activities of daily living like walking and balancing, which are fundamental indicators of health linked to fall risk and mortality. Despite its importance, there exist few methods that quantify lower limb control. This study evaluated whether the variability of fifteen-second circular leg movements relates to lower limb control, as assessed by a footedness questionnaire, and whether it also reflects functional performance in a postural balance task. Twenty-five healthy participants performed circular movements with their left and right legs, and they also completed one-legged stance trials on a force plate. Sway area and sway velocity were used as postural stability metrics. We found a linear relationship between each leg's acceleration variability and its log-transformed sway area and sway velocity. Moreover, across three repeated measurements per limb, circular acceleration variability was more reliable than the sway area and sway velocity as it had the largest intra-class correlation coefficient. Furthermore, the lateral difference between the left and right leg's acceleration variability was linearly related to the revised Waterloo Footedness Questionnaire's score. Together, these findings suggest that the variability of circular leg movements provides a robust and functional assessment of the lower limb's lateralization and postural stability.