Age-related plantar centre of pressure trajectory changes during barefoot walking.

Plantar centre of pressure (COP) variables during gait have been used to predict risk of injury, or consequences thereof. The aim of this study was to determine the effect of age on the COP trajectory during barefoot gait at a self-selected speed. 287 participants (aged 18-80year, 163 women) walked barefoot at self-selected speed across a Footscan force platform, completing five trials for each side. COP trajectories were extracted and trajectory-level canonical correlation analysis was used to test their correlation with age. Post hoc linear regressions were performed on the medio-lateral (COPx) and anterior-posterior (COPy) components. The test statistic trajectory exceeded the critical threshold for the left (p=0.001) and right foot (p=0.003). Post hoc analyses showed positive correlation between age and COPx in late stance, placed more laterally with increasing age, while no significant correlation was found for COPy. While no significant correlations were observed for the test statistic trajectory during heel strike and mid-stance, post hoc analysis indicated that the COPx component was placed more laterally at heel strike for the left foot with increasing age (p=0.016). The findings suggest that older individuals tend to push-off with less metatarso-phalangeal dorsiflexion. These results do not necessarily imply that ageing itself causes the observed correlation. Further evidence is needed to determine whether the laterally placed COP during roll-off may be a useful factor for determining risk for falling in the older population, or as a risk for future injuries or overuse disorders.