Trunk Flexion/Extension Excursion, Forces at the Feet and Gait Timing in Tactical Belt and Gear Vest Load Carriage

Background: 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. Research Question: 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. Methods: 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. Results: 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. Significance: 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.