MOVEMENT PLANNING AND POSTURAL ADJUSTMENT IN SINGLE AND MULTIPLE STEPS INITIATON

Abstract

Background: This study was designed to identify possible neurological as well as the cognitive factors on how people program their step and stop. Specifically, we use a simple vs choice condition task, which contains 1 to 3 steps under both conditions, to examine the reaction time and anticipatory postural adjustment (APA) phase duration. Methods: Eight healthy young college students (four female, four male) were enrolled in this study. Each of them performed a simple reaction task and a choice reaction task in response to a visual cue. Each task contained situations to take one or several steps. During the test, ground reaction force and position data were collected to further analyze initiation phase latency. Reaction time, release phase, transition time, double support phase, and the total time will be calculated as our dependent variables. Two-way analysis of variance (ANOVA) with Tukey HSD post hoc testing was used to analyze data. Results: Between simple reaction task and choice reaction task, choice reaction task required significantly longer time to finish in reaction and release phase. However, simple reaction task required significantly longer time to finish in transition and double support phase. Number of steps did not affect reaction time, but release, transition and double support phase were significantly affected by number of steps. Specifically, multiple steps task required more time to perform on release and transition, but single step task required more time on double support phase. All four types of APAs were significantly different from each other with an ascending trend from Correct Trials to Multiple Error Trials in release phase. Transition phase had a descending trend with multiple error trials took the least time to finish. Conclusion: In choice reaction task, planning two or three steps ahead cost more time to initiate compared to planning one step. Single step stepping task evaluation period is an online process with program of “stop” actually occurred during double support phase. Error trials tended to have a compensation effect which means durations after release phase had a descending trend with multiple error trial took the least time to complete.