Effects of stroboscopic disruption on static postural control in elderly individuals based on rambling and trembling...

Purpose: This study investigated the effects of stroboscopic disruption (SD) on postural control strategies in elderly individuals by comparing center of pressure (CoP) variables between young and elderly individuals during bipedal standing tasks, with and without SD. Methods: Thirty-five participants, 15 young and 20 elderly, completed 60-second bipedal quiet standing trials on a force plate. Excluding the initial and final 10-second preparation and recovery phases, the central 40 seconds of CoP trajectory were quantified using timedomain and frequency-domain parameters across the medial-lateral (ML), anterior-posterior (AP), and resultant spatial (RS) directions. Rambling (RM) and trembling (TR) components were also extracted. Statistical analysis was performed using a linear mixed-effect regression (LMER). Results: SD significantly affected CoP control, with the elderly exhibiting greater changes in most variables than the younger group. During the transition from transparent to SD conditions, time-domain parameters showed a significant increase in mean movement distance and root mean square in the RS direction for both traditional and RM components among the elderly. Additionally, the 95% confidence circle and ellipse areas were larger in the elderly group. In the frequency-domain parameters, such as 80% power frequency, frequency dispersion, and concentrated frequency decreased in the AP and RS directions for both traditional and RM components in the elderly group. Conclusions: The reduction in visual inputs caused by SD leads to decreased flexibility and automaticity in the postural control of elderly individuals, making it more difficult for them to control CoP sway and adapt to changes in visual input compared to younger individuals.