Kinematic effects on the lower limb caused by urban terrain cross-slopes

Walking on cross-sloped surfaces is common in urban environments and can be challenging for individuals with lower limb pathologies. Walking on a cross-sloped surface places one limb (upslope limb) in a higher position relative to the other (downslope limb), causing asymmetry. The effects of sex and walking speed on gait over a cross-sloped surface and the slope angle at which gait adaptations occur is unknown. Sixteen participants (nine female) completed walking trials on level, 2°, 4°, 6°¸ 8°, and 10° cross-slopes at a self-selected pace (1.12 ± 0.09 ms^-1) with the 10° condition repeated for self-selected slow (0.81 ± 0.14 ms^-1) and fast (1.43 ± 0.14 ms^-1) paces. Ankle, knee and hip joint angles were analysed at midstance. Greater eversion for slopes over 2° and inversion for slopes over 4° were necessary for upslope and downslope limbs, respectively. Males and females exhibited different hip kinematics when walking on a cross-sloped surface. Ankle dorsi- and plantarflexion changed with walking speed on a cross-sloped surface. Thus, slope angle, speed, and sex all resulted in differences in gait pattern on a cross-sloped surface. People use the end range of motion of their ankles when walking in commonplace urban settings. This may be an impediment to mobility for populations with reduced ankle mobility. As the cross-slope conditions tested in this paper are encountered every day in urban environments, the findings suggest that ambulation over cross-sloped surfaces may be an important task to consider in future designs of interventions for the lower limb.