Zusammenfassung

OBJECTIVES The current investigation examined the effects of a dual task execution, based on the shape of the base of support (BOS) and the task characteristics (i.e., dual or non-dual tasks), on the posture control, and how the interaction effects appear according to the combination of the two variables. METHODS A total of 22 young adults (11 males and 11 females) participated in the study. The participants were instructed to stand quietly based on the shape of their BOS (normal stance, semi-tandem, or tandem) on two left and right force plates. For the dual tasks, an inverse calculation in which the subjects quietly stated to the examiner three-digit numbers (between 300 and 900), after subtracting them by 7, was conducted. A two-way repeated measures ANOVA with two within factors was used. The dependent variables were set as the linear parameters (mean velocity (MV), RMS, and 95% ellipse sway area (CEA)), power frequency parameters (95% power frequency density (F95) and mean frequency (MF)), and complexity parameters (sample entropy (SampEn) and fractal dimension (FD)) of the center of pressure (COP) time series at each anteroposterior (AP) and mediolateral (ML) direction. RESULTS For the linear parameters, RMS_AP and CEA had an interaction effect on the shape of the BOS and the presence of dual tasks (p<.05). For the frequency parameters, F95_AP and MF_AP had an interaction effect on the shape of the BOS and the presence or absence of dual tasks (p<.05). For the nonlinear parameters, SampEn_AP and FD_AP had an interaction effect between the shape of the BOS and the task characteristics (p<.01). CONCLUSIONS Postural control during the intervention of a cognitive task is complicated based on the characteristics and difficulty of the task. The reduced movement of linear variables and the increased complexity and frequency variables when under unstable postural control (i.e., tandem standing) while simultaneously conducting dual tasks reflect the active and efficient stabilization strategies of young ...