Mirror versus stationary cross feedback in controlling the center of foot pressure displacement in quiet standing in elderly subjects

Objective: To investigate the effect of mirror feedback on postural control during quiet standing in elderly adults. Design: Before and after intervention trials. Setting: Pneumology center in France. Participants: Eleven elderly adults (mean age, 70.7+/-4.6y; mean body weight, 64.5+/-15.0kg; mean height, 161.4+/-12.0cm). Interventions: Participants were asked to stand upright, as immobile as possible, in 2 eyes-open and mirror-feedback conditions. The latter experimental condition consisted of supplying the subjects with their frontal reflection by positioning a mirror in front of them. Main Outcome Measures: Foot center of pressure (COP) displacements in the mediolateral (ML) and anteroposterior (AP) directions were recorded using a force platform. Results: The mirror-feedback condition had different effects on postural sway, depending on the direction: range, variability, and maximal instantaneous speed of the COP displacements decreased in the ML direction, whereas these effects remained unchanged in the AP direction. Conclusions: This study provided evidence that mirror feedback may put elderly adults at lower risk of falling.