Estratégias de controle do equilíbrio em idosas saudáveis

Abstract

Control of postural balance is the ability to keep the body static or moving within the support base without falling through sensory transmission and motor programming performed by the neuromuscular system. With aging, there is a decrease in executive functions and physical abilities that can directly influence the execution of automatic tasks, such as standing and walking. Balance assessment can be performed with the Wii Balance Board (WBB) by measuring the displacement of the pressure center in the anteroposterior (CoP ap) and mediolateral (CoP ml) directions. However, CoP behavior can be influenced by external factors such as vision deprivation and dual task (cognitive + motor task simultaneously) and internal factors such as physical conditioning and age. Thus, the present thesis seeks to investigate, through compiled studies, the factors that interfere with the control of postural balance in older women to detect possible motor strategies performed for stability preservation. The first study aimed to analyze the oscillation of the center of pressure (CO) during static balance in the presence or absence of a cognitive task in older women. The sample comprised 31 healthy older women aged 66 ± 7 years (mean ± standard deviation). Balance assessment was performed in a static position with eyes open (AO) and eyes closed (OF) (simple motor tasks) and with dual-task (DT) using the Wii Balance Board (WBB) to obtain the values of CoP ap and CoP ml. The Mini Mental State Examination (MMSE) performed the cognitive screening. The CoP values calculated the area of oscillation (SA cm²), total displacement (DT cm), and CO. Friedman's test was used to compare EO, CE and DT. The percentage of DT interference was used to quantify cognitive load at equilibrium, while the Spearman correlation coefficient was used to assess the association of cognitive domains and CO. All variables were analyzed with a significance level of p<0.05. A significant difference was observed in the oscillation of the CoP in the mediolateral direction (CoP ml) (p<0.01), with median values of 25 (minimum: 8 – maximum: 43) in dual-task, 23 (4 – 36) with eyes open and 21 (5 – 41) with eyes closed. The results show that the dual-task impairs the control of postural balance, with greater oscillation of the CoP in the mediolateral direction (CoP ml) beyond the limits of stability when compared to single tasks. The second study aimed to analyze the effect of physical exercise on dual-task processing in healthy older women performing static balance. The sample consisted of 16 healthy older women aged 66 ± 7 years (mean ± standard deviation). Balance assessment was performed in a static position with AO, OF, and DT using the WBB for obtaining the values of CoP ap and CoP ml. All the older women underwent training (24 sessions) with moderate effort, with different exercise programs, aerobics, strength, and virtual reality. CoP ap and CoP ml were analyzed over time pre- and post-training. The Wilcoxon test was used to compare pre- and post-training. All variables were analyzed with a significance level of p<0.05. A significant difference was observed in the median of the CoP ml (p<0.01) between the pre- and post-training periods in dual-task (0.16 - 0.03), with eyes open (0.11 - 0.02) and eyes closed (0.09 – 0.06), as well as there was a significant difference in the median of the CoP ap (p<0.01) between the pre- and post-training period in dual-task (0.04 – 0.26), with eyes open (0.29 – 0.09) and eyes closed (0.20 – 0.31). The results show that the physical exercise program reduces the oscillation of the CoP ml post-training with improved performance in dual-task, associated with improved attention. In the previous study, the objective was to analyze the creation of a postural control index and to establish a classification model for the postural control strategy of older women according to different age groups by computational intelligence. The sample consisted of 78 healthy older women, divided into 60-74, and more than 75 years. They were classified as Older Adults (OA) and Oldest Old (OO). The balance assessment was performed in a static position with OA and OF using the WBB, obtaining the values of CoP ap and CoP ml. A Decision Tree elaborated the qualitative classification of postural balance control according to the groups. The CoP directions were probably decisive for the predictions of postural balance control strategies according to age group, with 95% accuracy and 83% model accuracy. The results found that MI presents greater CoP ap oscillation as a posture correction strategy compared to JI. In conclusion, the first study shows that the cognitive load during the dual task impairs postural control more in the mediolateral direction, in addition to showing the use of WBB to assess cognitive interference in postural control. The second study shows that physical exercise programs for the elderly can simultaneously improve motor-cognitive performance, associated with improved divided attention. The third study shows that older adults change their postural sway predominantly from CoP ml to CoP ap in the early and later stages of aging. The classification method described can detect postural changes and consider the impact of aging on standing balance in the elderly. Thus, the studies presented changes in the balance control strategies of healthy older women according to the complexity of the task, after carrying out a physical exercise program and to age group.