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Background: The influence of load carriage in operational police officers is not well understood despite a relatively high injury rate. Assessing load related changes in head and torso coordination may provide valuable insight into plausible injury mechanisms., Research Question: Do typical police tactical vest loads alter head and torso coordination during running?, Methods: Thirty-eight UK police officers ran at a self-selected pace (>2 ms -1 ) on a non-motorised treadmill in four vest load conditions (unloaded, and low, high and evenly distributed loads). Peak head and torso tilt, and peak vest displacement were compared between all four conditions. Timings between vest and torso change of direction were compared between the three loaded conditions. The coupling angle between the head and torso calculated using modified vector coding were compared between unloaded and each loaded conditions using Statistical Parametric Mapping., Results: No significant differences were found between conditions for peak head or torso tilt alone (p > 0.05). Loading equipment low on the vest led to significantly greater mediolateral vest displacements (38 mm) away from the torso than a high (34 mm) or evenly distributed (30 mm) conditions. The vest was found to change direction vertically before the torso in the anterior-posterior direction, and then influence torso motion. The loaded conditions changed the head-torso coupling from in-phase (with head-dominancy) to anti-phase (with torso dominancy) between 55% and 77% stance. Anti-phase with a relatively stationary head and the torso rotating forward likely places a greater concentric demand on the posterior neck muscles relative to unloaded running., Significance: Current tactical vest designs allow significant extra displacement of load away from the body during running, altering coordination at the head and torso., Competing Interests: Declaration of Competing Interest This project formed part of a Knowledge Transfer Partnership, funded through Innovate UK in partnership with Arktis Endurance Textiles Ltd. The sponsors were not involved in the study design, collection, analysis or interpretation of data. The sponsor did not have a role in the writing or submission of this manuscript. The authors have no financial conflicts of interest to disclose., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Postural control deficits have been identified among individuals with chronic ankle instability (CAI) compared to healthy controls. Although deficits in static balance have previously been reported using center of pressure (COP) and, more recently, time to boundary (TTB) measures, the underlying mechanism behind these deficits warrants further investigation. It is unclear if there are differences in the spatial distribution of COP and TTB minima data points under the foot. Our purpose was to determine if there are differences in the location of the distribution of the COP and the TTB minima data points between groups with and without CAI. Fifty healthy and 61 CAI subjects participated in this case-control study. The subjects performed three successful 10-s trials of quiet single limb stance on a force plate with eyes-open and -closed conditions. Results showed that during eyes-open trials, the CAI group exhibited more COP and TTB minima data points on the anterolateral aspect of the foot compared to controls. With eyes-closed single limb balance, the CAI group demonstrated significantly more COP and TTB minima data points anterior to the horizontal midline of the foot compared to controls. Overall, the CAI group showed a greater anterior displacement of COP and TTB minima during single limb static stance compared to controls. This alteration may result from the CAI subjects adopting a more dorsiflexed position in an effort to keep the ankle in a more stable, closed pack position and limiting the available degrees of freedom in the distal lower extremity., (Copyright © 2011 Elsevier B.V. All rights reserved.)