The effect of visual targeting on ground reaction force and temporospatial parameters of gait

Abstract

Background. Visual targeting has been cited as a confounding factor for gait analysis in which measures of ground reaction force and plantar pressure are obtained. Objective. To investigate the effect of visual targeting on temporospatial and kinetic aspects of gait when small targets, such as pressure platforms, have to be used. Design. A within subjects repeated measure design was used to measure step parameters and ground reaction forces of 11 healthy volunteers. Methods. Subjects were required to walk over a 10 m walkway at a self-selected pace. A 30×24 cm 2 target area was superimposed over a hidden Kistler force plate (60×90 cm 2) mounted at the midpoint of the walkway. Step parameters and ground reaction forces were measured with and without the presence of the target. Ground reaction forces were analysed within the time-domain. Results. Subjects used visual control strategies when approaching targets of similar dimensions to a pressure platform. These strategies were manifested by an increase in the variability of the step length onto the target ( P<0.05). However, targeting was observed to have no affect on the magnitude, timing and variability of ground reaction forces when measured within the time-domain and averaged over five trials ( P>0.05). Conclusions. Visual control strategies employed while walking toward a target area have no affect on ground reaction force parameters when measured within the time-domain. Relevance These findings demonstrate that targeting a 30 × 24 cm 2 target does not affect ground reaction force parameters, when a gait protocol that fine-tunes the start position is employed. The findings are relevant to gait research in which small force or pressure platforms are used to assess gait kinetics.