Gait parameters and stride-to-stride variability during familiarization to walking on a split-belt treadmill

Background: Subjects unfamiliar to walking on a split-belt treadmill may initially demonstrate an altered gait pattern or increased variability of gait parameters. While previous investigations have examined kinematic variables associated with familiarization time, the objective of this study was to determine the familiarization period required to obtain the most reproducible gait pattern through the assessment of kinetic, kinematic and spatio-temporal parameters during a single session of treadmill walking. Methods: Eleven healthy subjects participated in a single bout of treadmill walking which lasted 9 min. Kinematic and kinetic data were collected from the first 30s of each minute, beginning when the treadmill reached full speed. Means and standard deviations for knee flexion at heel strike, ground reaction forces, step width and step length were obtained to examine the changes in each variable over the 9 min. Mean r(2) values were evaluated for changes in variability from one stride to the subsequent stride for sagittal plane hip, knee and ankle joint angles and moments, as well as for vertical and horizontal ground reaction forces. Findings: Significant reductions in variability were found for vertical and horizontal ground reaction forces, knee flexion at heel strike and step length over 9 min. Only step width showed a change in the mean value across trials. There were no increases in r(2) values after the 5th min for any of the gait variables. Interpretation: The results suggest that in order to collect accurate data for gait analysis, subjects should be familiarized to the split-belt treadmill for at least 5 min prior to data collection. (C) 2009 Elsevier Ltd. All rights reserved.