The effect of visual targeting on ground reaction force and temporospatialparameters of gait

Background. Visual targeting has been cited as a confounding factor for gai t 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-selec ted pace. A 30 x 24 cm(2) target area was superimposed over a hidden Kistle r force plate (60 x 90 cm(2)) mounted at the midpoint of the walkway. Step parameters and ground reaction forces were measured with and without the pr esence of the target. Ground reaction forces were analysed within the time- domain. Results. Subjects used visual control strategies when approaching targets o f similar dimensions to a pressure platform. These strategies were manifest ed 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 targ et area have no affect on ground reaction force parameters when measured wi thin the time-domain.