The impact of shod vs unshod walking on center of pressure variability

Background The variability of center of pressure (COP) is a measure of stability commonly examined during quiet standing. While more recent research has examined the variability of COP during walking, an adequate comparison between shod and unshod walking conditions has yet to be made. Research question What is the influence of athletic footwear on the variability of COP displacement during walking? Methods In this intervention study, twenty healthy women (age 18–30 years) completed 2, 10-min walking trials, 1 shod and 1 unshod, during which ground reaction forces (GRF) and COP movement were collected by an instrumental treadmill. COP displacement was examined in the medial-lateral (ML) and anterior-posterior (AP) directions after being divided into quadrants based on the peaks and trough of each steps associated vertical GRF. A single MANOVA was used to determine effects of footwear and limb for each quadrant with the probability of a Type I error set at 0.05. Results Significant differences in variability were seen between footwear conditions in all quadrants in the AP direction and quadrants one and four in the ML direction. These results may be due to the structure of footwear, including midsole cushioning, altering the dynamics of the foot during walking. Significance The results of this study suggest that on average, athletic footwear reduces the variability of COP displacement in ML and AP directions. This may have implications for populations for whom variability of COP is determined to be undesirable.