No abstract

Mediolateral ankle moment control contributes to gait stability. Therefore, constraining ankle moment control might affect other stability mechanisms, including foot placement control. Ankle moments can be constrained by walking with a shoe with a ridge underneath the sole, narrowing the mediolateral support surface. Based on the literature, it seems that constraining ankle moment control in this fashion results in an increased step width and a decrease in the degree of foot placement control, as defined by the percentage of variance in foot placement that can be explained by CoM state. However, since that study was performed on a splitbelt treadmill and the narrow ridge could fit inside the gap between the belts, it is not evident whether these effects can be attributed to the constrained ankle moment control or to avoidance of this gap. Therefore, we investigated if the effects of ankle moment constraints are dependent on whether participants walk on a normal treadmill or a splitbelt treadmill. We included fourteen healthy young adults. Walking with constrained ankle moment control resulted in a wider step width on both treadmills. Yet, the increase in step width was larger on the splitbelt treadmill compared to on the normal treadmill. Moreover, we only found a decreased degree of foot placement control on the splitbelt, whilst the degree of foot placement control increased on the normal treadmill. We conclude that the effects of ankle moment constraints reported in our previous study were confounded by the use of a splitbelt. For future research, we recommend using a normal treadmill whenever possible, because the gap in a splitbelt treadmill might affect gait parameters.