Assessing the effects of gait asymmetry: Using a split-belt treadmill walking protocol to change step length and peak knee joint contact force symmetry.

Abstract Asymmetrical gait may affect important outcomes such as knee joint contact force (KJCF). A split-belt treadmill (SBTM) can be used to provoke changes in step length symmetry (SLsym) and may produce a similar response in KJCF symmetry (KJCFsym) between limbs. The purpose of this study was to explore the utility of employing a SBTM walking paradigm to alter KJCF and KJCFsym and to determine if changes in SLsym coincided with changes in KJCFsym. Twenty healthy individuals performed a standardized SBTM protocol, where baseline and post-adaptation conditions had tied belt speeds of 0.5 m/s and the split-adaptation condition used a 3:1 belt speed ratio. OpenSim techniques were used to produce normalized, averaged stance phase peak KJCF during baseline walking, early- and late-adaptation, and post-adaptation. SLsym and KJCFsym values were determined. Comparisons were made for symmetry values between early- and late-adaptation and between baseline and post-adaptation. SLsym and KJCFsym did not respond in the same manner during the walking conditions. While step lengths (SL) were asymmetric during early adaptation but become more symmetric by late adaptation (p