The speed-accuracy trade-off in human gait control when running towards targets

The study examined adjustments to gait when positioning the foot within a narrow target area at the end of an approach or ″run-up″ similar to the take-off board in long jumping. In one task, participants (n=24) sprinted toward and placed their foot within targets of four different lengths for 8-m and 12-m approach distances while ″running through″ the target. In a second task, participants (n=12) sprinted toward and stopped with both feet in the target area. Infra-red timing lights were placed along the approach strip to measure movement times, with a camera positioned to view the whole approach to measure the total number of steps, and a second camera placed to view the final stride, which was analyzed using an in-house digitizing system to calculate the final stride characteristics. In the run-through task, a speed-accuracy trade-off showing a linear relationship (r=0.976, p < .05) between target length and approach time was found for the 8-m amplitude. An accelerative sub-movement and a later targeting or ″homing-in″ sub-movement were found in the approach kinematics for both amplitudes. Final stride duration increased, and final stride velocity decreased with a decrease in target length.