(A, B) COM anterio-posterior (AP) displacements during standing with eyes open (EO), and eyes closed (EC), respectively. (C, D, E) Individual AP displacements during standing with 40 Hz vibration plotted against displacements during quiet standing in participants of HY, HE, and FR groups, respectively. (F, G, H) Individual AP displacements during standing with 30 Hz vibration plotted against displacements during quiet standing in participants of HY, HE, and FR groups, respectively. (I, J) COM medio-lateral (ML) displacements during standing with eyes open (EO), and eyes closed (EC), respectively. (K, L, M) Individual ML displacements during standing with 40 Hz vibration plotted against displacements during quiet standing in participants of HY, HE, and FR groups, respectively. (N, O, P) Individual ML displacements during standing with 30 Hz vibration plotted against displacements during quiet standing in participants of HY, HE, and FR groups, respectively. Designations as in Fig 3.