Can handling a weapon make soldiers more unstable?

Gait stability in soldiers can be affected by task constraints that may lead to injuries. This study determined the effects of weapon handling and speed on gait stability in seventeen soldiers walking on a treadmill with and without a replica weapon at self-selected (SS), 3.5 km·h⁻¹, 5.5 km·h⁻¹, and 6.5 km·h⁻¹ while carrying a 23-kg load. Local dynamic stability was measured using accelerometry at the sacrum (LDE_SAC) and sternum (LDE_STR). No significant weapon and speed interaction were found. A significant effect of speed for the LDE_SAC, and a significant effect of speed and weapon for the LDE_STR were found. Per plane analyses showed that the weapon effect was consistent across all directions for the LDE_STR but not for LDE_SAC. Weapon handling increased trunk but did not affect pelvis stability. Speed decreased stability when walking slower than SS and increased when faster. These findings can inform injury prevention strategies in the military. <b>Practitioner summary:</b> We determined the effects of two constraints in soldier’s walking stability, weapon handling and speed, measured at the trunk and sacrum. No constraints interactions were found, however, lower stability when walking slow and greater stability with the weapon at the trunk can inform preventive strategies in military training.士兵的步态稳定性可能受可引发运动损伤的任务约束因素影响。本研究探讨了武器携行与步行速度对17名士兵在跑步机上行走时步态稳定性的影响，实验设置了携行/不携行模拟武器两种条件，以及四种步行模式：自主选择步速（SS）、3.5 km·h⁻¹、5.5 km·h⁻¹与6.5 km·h⁻¹，且所有受试者均背负23 kg负重。研究采用加速度测量法，在骶骨（LDE_SAC）与胸骨（LDE_STR）处采集数据以评估局部动态稳定性（Local Dynamic Stability, LDE）。分析结果显示，武器携行与步行速度未呈现显著交互效应；针对骶骨处的LDE（LDE_SAC），仅步行速度存在显著主效应，而针对胸骨处的LDE（LDE_STR），步行速度与武器携行均存在显著主效应。分平面分析表明，武器携行对胸骨处LDE稳定性的影响在所有运动方向上均保持一致，但对骶骨处LDE则无此规律。武器携行可提升躯干稳定性，但对骨盆稳定性无显著影响；步行速度低于自主选择步速时，步态稳定性会下降，反之高于自主选择步速时稳定性则提升。本研究结果可为军事领域的运动损伤预防策略提供参考依据。<b>从业者摘要：</b>本研究明确了影响士兵步行稳定性的两类约束因素——武器携行与步行速度，并通过躯干与骶骨处的监测数据完成量化评估。研究未发现两类约束因素间存在交互效应，但结果显示低速步行时稳定性更低，且携行武器可提升躯干稳定性，上述发现可为军事训练中的损伤预防方案提供指导。