# How Different Load Carriage Scenarios Impact the Gait in Police Officers
## 4 Discussion  
The purpose of the study was to examine the effects of load carriage on the spatiotemporal and kinetic gait changes in special police officers. The main findings of the study are: (1) no significant spatiotemporal gait changes are observed, when applying heavier loads, and (2) gait kinetics, mainly ground reaction forces and plantar pressures under the different foot regions significantly increased after heavier loads. In agreement with several other studies in military personal, our study showed that heavier loads did not have significant effects on spatiotemporal gait variables in special  
Figure 4: Changes in plantar pressures beneath specific foot regions under different loading conditions (N = 30). Figure 3: Changes in ground reaction forces beneath specific foot regions under different loading conditions of no load (only body weight), L1 (5 kg load), L2 (25 kg load) and L3 (45 kg load), (N = 30). police officers, including step length, stride length, cadence, and step width [8; 9; 10; 11; 23; 24], irrespective of the load type carried. Most recently, a systematic review by [PERSON] and [PERSON] [7] has suggested that nonsignificant effects may be explained by evenly distributed loads such as body armor vs. loads borne on the back. It Although we found no significant changes in spatiotemporal biomechanics, some variables like stride length and cadence gradually tended to increase with heavier loads, which is in line with previous studies [9; 10]. Because special forces are potentially more experienced in heavy load carriage, spatiotemporal structure of walking becomes too robust to be affected by additional heavier loads [14]. Changes in gait kinetics under heavier loading conditions obtained in this study are in line with previous studies [1; 4; 8; 9; 10; 12; 13]. Specifically, both vertical ground reaction forces and plantar pressures under the different foot regions significantly increased with heavier loads. The mechanism underlying this phenomenon is based on the added mass of the carried load, where the associations between the increased forces and loads are proportional [13]. Indeed, previous evidence has shown that the increased ground reaction forces are congruent with the increased plantar pressures associated with carrying additional load [12]. The greater impact forces and plantar pressures beneath the foot regions increase the incidence of load carriage-related injuries [1], leading to greater breaking and propulsive forces during walking [8; 10; 13]  
This study is not without limitations. Although we examined both spatiotemporal and kinetic gait changes under different loads, we did not measure gait kinematics and electromyographs properties. A systematic review by [PERSON] and [PERSON] [7] showed that heavier loads significantly increased hip and knee range of motion, hip and knee extension moments, ankle plantar flexion moments, hip, knee, and ankle sagittal power generation and the activity of antigravity and propulsive trunk and leg muscles. Secondly, the participants were instructed to walk at self-selected speed over the platform in laboratory conditions. Most of previous studies conducted among military personnel have used a predetermined speed by using treadmill walking or running modes [7]. It is possible that task-specific walking speed would give different changes in given variables. Thirdly, physical fitness was not assessed as a mediator. A higher level of physical fitness has been suggested as a protective factor between heavier load carriage and gait biomechanics [17]. Fourth, the length of a walkway might be short, causing the speeds to be \"clipped\". Fifth, we did not test civilians, so we cannot compare our findings to the general population. Sixth, the load was not tested independently of how it was distributed on the body. Finally, the testing procedure was based on walking barefoot, whereas walking under specific conditions and tasks using insole shoes sensors inside the footwear might have given different results.