The effect of different unstable footwear constructions on centre of pressure motion during standing

Background: The aim of this study was to test the effect different unstable footwear constructions have on centre of pressure motion when standing. Methods: Sixteen young female volunteers were tested in five conditions, three unstable footwear (Reebok Easy-Tone™, FitFlop™ and Skechers Shape-Ups™), a standard shoe and barefoot in a randomised order. Double and single leg balance on a force plate was assessed via centre of pressure excursions and displacements in each condition. Results: For double leg and single leg standing centre of pressure excursions in the anterior-posterior direction were significantly increased wearing Skechers Shape-Ups™ compared to barefoot and the standard shoe. For the Reebok Easy Tone™ during single leg standing excursions in the anterior-posterior direction were significantly greater compared to the barefoot condition. Cumulative displacement of the centre of pressure in medial-lateral direction increased significantly during single leg standing when wearing Skechers Shape-Ups™ compared to barefoot and standard shoe as well as for Reebok Easy Tone™ vs. barefoot. Discussion: It would appear from these quiet standing results that the manner of the construction of instability shoes effects the CoP movement which is associated with induced instability. Greater CoP excursion occurred in the A-P direction while the cumulative displacements were greater in the M-L direction for those shoes with the rounded sole and soft foam and those with airpods. The shoe construction with altered density foam did not induce any change in the CoP movement, during quite standing, which tends to suggest that it is not effective at inducing balance. Not all instability shoes are effective in altering the overall instability of the wearer. © 2014 Elsevier B.V.