Muscle Activity During Postural Stability Tasks: Role of Military Footwear and Workload

Chander, H., Knight, A., Garner, J. C., Wade, C., DeBusk, H., Wilson, S. J., Gdovin, J. R., Hill, C. M., & Carruth, D. W. (2017). Muscle Activity During Postural Stability Tasks: Role of Military Footwear and Workload. Proceedings of the American Society of Biomechanics Annual Conference. Boulder, CO. 296-297.

The term “military personnel” is a large umbrella term for all United States service members regardless of assigned duties. Military personnel jobs vary from infantry, medical personnel, mechanics, flight controllers, pilots and other personnel. Many of the military occupations consist of environments that are further inclusive in extrinsic factors such as diverse terrains, lack of light, increased decibel range, unstable ground surfaces and intrinsic factors such as fatiguing workloads including load carriage. Proper postural control and slip responses are essential in military settings in order to prevent falls. The US Army Annual Injury Epidemiology Report in 2008 found 18.4% of all causes of injuries were attributed to falls/near falls [1]. Slips, trips and falls (STFs) are a consequence of failure of normal locomotion and equilibrium recovery following an induced imbalance [2]. During a slip, there are correctional responses, such as increased knee flexion, and ankle plantar flexion. Footwear characteristics such as the boot shaft height, mass, mid-sole hardness and thickness, elevated heels and type of material of the footwear influence balance and gait and ultimately the slip propensity. Intrinsic factors such as decrements of the postural control systems can contribute to falls. Dysfunction in the visual, vestibular, somatosensory or the musculoskeletal system and any undue muscular fatigue due to excessive workload in the military environment can potentially lead to falls. Thus, the purpose of this study was to examine kinematics of the lower extremity during slip events while wearing military footwear before and after a simulated military workload.