Effect of Impeded Medial Longitudinal Arch Drop on Vertical Ground Reaction Force and Center of Pressure During Static Loading

Background: Arch supports commonly used to alleviate foot pain can impede the normal drop of medial longitudinal arch (MLA) thereby altering its function. The purpose of the study was to examine the effect of using arch supports on vertical ground reaction force (GRF) and center of pressure (COP) during simulated midstance while the foot was statically loaded. Materials and Method: Ten healthy young subjects were recruited. Two dimensional (2D) analysis of the MLA was captured for both barefoot (BF) and arch support conditions before and after loading via a custom made weight loading apparatus. The foot was loaded and positioned to simulate the midstance phase of walking. Two-dimensional reflective markers demarcated the MLA and captured with the loaded foot on a force platform. The impeded MLA drop was compared between the unloaded BF, loaded BF and loaded arch support conditions. The vertical GRF, the anterior-posterior and the medial-lateral COP displacements were also measured in response to the impeded MLA by the arch supports. Results: The arch supports impeded the MLA drop (p < 0.05) and shifted the COP toward the medial side (p < 0.05), specifically for the rearfoot (calcaneal segment region), but no changes were determined for the vertical GRF (p > 0.05). Conclusion: The impedance of MLA drop by the arch support altered the pattern of the ML COP shift in the rearfoot region. Clinical Relevance: The use of arch supports may not relieve painful foot conditions that are associated with excessive calcaneal eversion indicated by altering COP shifts in localized foot regions.