INTRODUCTION and AIM
Police officers are commonly reported to have a high prevalence of lower back pain (1) which has been associated with use of heavy utility
belts together with body amour (2, 3). Offloading the lower back and pelvic region by relocating equipment from the utility belt to a load bearing
vest and leg holster has been suggested as an alternative means of carrying equipment required by police (2). The relative effects of load
bearing vests on pelvic kinematics in currently unclear. It is hypothesized that anterior placement of equipment on a utility belt will provoke
an increase in anterior pelvic tilt. The aim of the study was to compare pelvic kinematics in a sample of Swedish police officers while wearing
a utility belt versus a load bearing vest.
PATIENTS/MATERIALS and METHODS
Nineteen participants (F=10/M=9) were recruited for the study. All worked as active duty police officers in a middle sized municipality in
Sweden. Participants had no musculoskeletal problems at the time of data collection. All participants were tested under three conditions
wearing: a) standard utility belt with standard body amour, b) a load bearing vest with standard body amour and thigh holster and c) no
equipment. Testing conditions were randomised. Participant walked at self-selected speed on an 8 metre walkway. Kinematic data was
collected using a three-dimensional gait analysis system (Qualisys Medical AB). A surface cluster marker model was used to collect data.
Due to placement of equipment around the pelvic region reflective markers could not be placed directly onto pelvic landmarks. As a result a
u-shaped rigid carbon fibre frame containing a cluster of three markers was manufactured to partially fit under the equipment belt. This frame
was mounted on the sacrum and tracked movement of the pelvis during dynamic trials.
Pelvic kinematics during stance and swing phase was calculated and compared across the three conditions using Friedmans ANOVA. A
significant difference was observed in maximum pelvic tilt when comparing the standard utility belt and the load bearing vest conditions (Table
1). When wearing the load bearing vest the pelvis was found to be tilted more posteriorly relative to the utility belt condition (p≤0.05). No
differences were observed in the other planes or in range of motion of the pelvis.
DISCUSSION and CONCLUSIONS
The results demonstrated a significant difference in sagittal plane pelvic kinematics when comparing the load bearing vest to the standard
utility belt. Angular differences were however relatively small and their clinical relevance in terms of low back pain is yet to be determined.
Further analysis should investigate kinematic changes at the hip and trunk to see if any differences at these levels, combined with the pelvic
tilt results presented in this study may have a cumulative effect which results in an increased risk of low back pain.