Proactive stability control while carrying loads and negotiating an elevated surface.

In this study, proactive stability control while handling loads and negotiating an elevated surface was examined. Ten young healthy males completed two gait-mode conditions--level walking and negotiating a raised surface. Load-handling conditions were: no load, empty box (reduced visual information), and loaded box (reduced visual information combined with increased inertial load). The lower limb trajectory in the sagittal plane was not modified as a function of reduced visual information or increased inertial load. The step width decreased while stepping over the surface and carrying the loaded box. The trunk pitch angle was biased backwards for both the empty box and the loaded box. When carrying the empty box and negotiating the surface, the trunk pitch range of motion (ROM) increased which may have been a strategy to increase visual exteroceptive information. As increased net trunk pitch could destabilize the system, concurrent stabilizing strategies--decreased gait velocity and reduced net trunk roll velocity--were observed. To meet the equilibrium goals when carrying the loaded box, the trunk pitch ROM and net pitch velocity were reduced during both level walking and surface accommodation. Trunk roll ROM was reduced when carrying the load and negotiating the surface. This study extends our knowledge regarding whole body coordination strategies during anticipatory locomotor adaptations.