Law enforcement agents often carry gear or equipment loads, which have a history of causing low back pain. Traditionally, police equipment is carried along a belt, which loads the pelvis and lower limbs. Over the shoulders, through a vest is an alternative method of load carriage for law enforcement agents. The aim of this study was to evaluate the differences in gear load carriage for law enforcement agents while walking. We hypothesize that there will be a difference in forces on the feet, timing of forces on the feet and trunk angle while distributing weight in a belt and a vest carriage strategies.
Twenty-nine healthy participants were recruited to perform load carriage in three different conditions: a control trial (C) with no gear weight, a loaded nylon tactical gear belt (TB), and an anterior-loaded gear vest (ALV). The gear load carriage conditions had a total of 9.07 kg (20 lbs.) of weight. Moticon force sensors were placed in each shoe before participants walked on a treadmill for three minutes per condition. Data included gait timing and ground reaction forces that were measured using the Moticon force sensors. Trunk flexion/extension excursion was captured by a motion capture system.
Trunk flexion/extension excursion was significantly lower in the TB condition when compared to the C condition (p= 0.002). Double support time in the ALV condition was significantly longer when compared to the C condition (p= 0.023). Stance duration in the ALV condition was significantly longer when compared to the C and TB condition (p= 0.008 and 0.009, respectively). Mean ground reaction force was significantly greater in both the TB and ALV conditions, both with p= 0.00.
There were differences found in mean trunk flexion/extension excursion, and gait timing when participants carried a gear load, demonstrating that participants walked in a more stable posture when they carried a load.