Physiological and Biomechanical Evaluation of a Prototype for Load Carrying System

Soldiers are often required to carry loads using backpacks while performing military tasks. Carrying loads causes elevated energy expenditure, increases forces acting on the musculoskeletal system and may lead to early fatigue and orthopedic injuries. Recently, wheel-based assistive devices (WBD), were designed to reduce the physiological and biomechanical stress on the soldier. A prototype of this newly developed WBD was evaluated. Ten volunteers participated in three exercise sessions on a treadmill as follows: no load, with a military backpack (40% of body weight) and with the WBD. Physiological monitoring included: heart rate, core body temperature, oxygen consumption, subjective comfort and biomechanical measurements included: stance analysis, vertical ground reaction forces, gait analysis and contact pressure acting on the shoulder. While there was a tendency for a lower biomechanical strain using the WBD, no physiological advantage of the WBD was noted. It is assumed that the reduction in the physiological differences were due to increased activity of the stabilizer muscles in an attempt to maintain balance while walking.