Lower-Extremity Kinematics and Spatiotemporal Differences Between Normal Walking and Walking While Maintaining Weapon Aim

Although exoskeletons for tactical athletes are potentially beneficial tools to increase survivability and enhance operational capabilities, they often do not account for variations from basic movements. Tactical movement patterns must be investigated to best guide device design and mitigate restriction of the user’s abilities to execute duties. The purpose of this study was to identify if biomechanical patterns are difference between walking while maintaining weapon aim (i.e., ‘shoot on the move’, SM) and normal walking. Twenty-two male active-duty Army Soldiers performed normal walking and SM under three speed conditions: (1) self-selected slow, (2) standard (1.12 m/s), and (3) self-selected fast. Lower extremity kinematics and spatiotemporal parameters were collected. Unadjusted and adjusted models were performed to determine the effects of walking and speed conditions on dependent variables. Individuals exhibited larger lower extremity flexion angles during SM than during normal walking (p < 0.01). Smaller strides were observed during SM than during normal walking (p < 0.01). No difference in time spent in double limb support were observed between walking tasks (p = 0.97). Tactical athletes exhibit different movement patterns during SM compared to normal walking. Lower extremities are more flexed, and strides are shorter during SM to minimize vertical movement and increase stability, suggesting that occupationally relevant movements may not directly translate to basic movements. Information on occupationally relevant movements should be accessible to exoskeleton designers to build optimum control systems that will aid and not hinder tactical athletes in their roles to serve and protect.