Effects of Load Carriage on Postural Sway and Relative Ground Reaction Forces in Special Police Officers: A Cross-Sectional Study

Abstract

Although excessive load carriage results in biomechanical gait changes, little evidence has been provided regarding its impact on postural sway. Therefore, the main purpose of this study was to determine whether heavier loads have effects on changing foot stability and postural sway in special police officers. Thirty male special police officers (age = 40 ± 6 years, height = 180 ± 5 cm, weight = 89 ± 8 kg) were assessed in four conditions: (1) carrying no load, (2) carrying a 5 kg load, (3) carrying a 25 kg load, and (4) carrying a 45 kg load. Foot characteristics during standing were assessed with Zebris pedobarographic pressure platform. Heavier loads increased the center of pressure (COP) path length and average velocity, length of minor and major axis, and 95% confidence ellipse area, while a decrease in angle between Y and major axis was observed. Relative forces beneath the left forefoot and right backfoot regions decreased and an increase in relative forces beneath the left backfoot and right forefoot was observed. When carrying heavy loads, static foot parameters rapidly changed, especially in COP path length and average velocity.

Load Carriage and Changes in Spatiotemporal and Kinetic Biomechanical Foot Parameters during Quiet Stance in a Large Sample of Police Recruits

“…To the best of the authors' knowledge, this is the first study aiming to investigate the effects of a '3.5 kg load' on spatiotemporal and kinetic foot parameters during quiet standing. Previous evidence has confirmed that heavier loads may impact several foot characteristics during a quiet stance, including increases in the mean postural sway during a double stance, the center of pressure path length, the average velocity and the lengths of the minor and major axes with a decrease in the angle between the Y and major axes [11,20,25]. Evidence suggests that load carriages produce greater foot changes and affect body sway during standing, which directly disrupts the body's center of mass, causing it to shift from a point of stability to the boundaries of the base of support.…”

Balance Training and Shooting Performance: The Role of Load and the Unstable Surface

“…We found that participants who stood on an unstable surface while carrying an external load had the worst shooting scores and a lower percentage of COG. Previous studies have shown the adverse effects of load on soldier and police officer postural sway [ 8 , 9 ] and shooting accuracy [ 13 ]. Gil-Cosano et al [ 13 ] documented a 30% decline in shooting score when soldiers wore a backpack (19.5 ± 2.4 kg, equivalent to 24.2 ± 3.4% of their body weight).…”

“…Multiple factors within military and law enforcement settings, such as the carriage of additional equipment (e.g., protective vests and backpacks) and the negotiation of uneven terrain, can adversely affect the balance of police officers and soldiers [ 1 , 5 , 7 , 8 ]. Consequently, this can impact their shooting prowess and overall capacity to endure in combat scenarios.…”

“…Therefore, it is recommended to prioritize the development of postural balance, especially for young soldiers, police officers, and novices engaged in specialized training exercises that require precise body and rifle stabilization [ 1 , 5 ]. Considering the importance of postural balance in shooting performance, it is advisable to promote the use of supplementary proprioception training programs to improve shooters’ postural abilities [ 1 , 5 , 8 , 12 ]. The aim of this study was to examine the effects of a proprioception training program on shooting performance in novice military members.…”