Influence of foot position on static and dynamic standing balance in healthy young adults

Abstract

Background: Postural instability is a condition affecting many people during normal ageing or those suffering from neurological or orthopaedic diseases. Posturography has become an important tool to assess balance. Standards of performing posturography, however, are not sufficiently elaborated.Purpose: To investigate the influence of different foot positions, specifically a self-selected foot position, on maximal sway amplitudes during static and dynamic (limits of stability) standing balance tasks.Materials and methods: In this cohort study with repeated measurements 24 healthy young adults completed five conditions: a condition with self-selected foot position and four conditions with set feet distances (feet together, 10 cm, 20 cm, 30 cm). Maximal sway amplitudes of the centre of pressure recordings were analyzed in antero-posterior and medio-lateral axes.Results: Analysis of the self-selected position showed a mean foot distance of 20.3 (4.6) cm, which significantly positively correlated with the participants’ body height and sex. Repeated measurement ANOVAs revealed a significant effect of foot position on the sway parameter in both directions, which was more pronounced in the medio-lateral axis. Pairwise comparisons in this axis showed two homogeneous subgroups. One composed the ‘feet together’ and ‘10 cm’ conditions, and the other the remaining three conditions. The self-selected position did not lead to the lowest sway values in static trials nor to the largest values in dynamic trials.Conclusions: Taking these results into account we recommend using a self-selected foot position when performing posturography. The sway parameters are not different to predefined stable foot positions. Furthermore, the self-selected position reflects a more natural and individually optimized stance and also takes body geometry into account.