Fig. 3

Effects of prolonged exposure to optical flow perturbations on lateral margin of stability (MoS) and its variability in older participants. Group average (±standard error) (a) lateral MoS and (b) its associated variability calculated at its stance phase minimum and at heel-strike for the perturbation session. The repeated measures ANOVA revealed significant main effects across the perturbation session (baseline, early, late, post) for lateral MoS at heel strike (p = 0.012), the variabilities of lateral MoS at its stance phase minimum (p < 0.001) and at heel strike (p < X). Single asterisks (*) indicate significantly different from baseline values in older adults (p < 0.05). Double asterisks (**) indicate significantly different between early and late time points for prolonged exposure in older adults (p < 0.05). We also note differences approaching significance between baseline and early for lateral MoS at heel-strike (p = 0.051) and between early and late for stance phase minimum lateral MoS variability (p = 0.065) (^a)