Preliminary evidence suggests that balance deficits constitute an important secondary impairment in individuals with chronic obstructive pulmonary disease (COPD). The main objective of this thesis was to describe balance impairment and fall risk in individuals with COPD and to examine interventions for improving balance and reducing fall risk in the context of pulmonary rehabilitation. The first study of this thesis showed that falls are common in patients with COPD and that fallers are characterized by impairments in standard clinical balance measures, such as the Berg Balance Scale and Timed Up and Go. In the second study, we found that the exercise component of conventional pulmonary rehabilitation has only modest effects on balance and fall risk in COPD, highlighting the need to examine the role of balance-specific training for these patients. The third study of this thesis identified the postural control subsystems most responsible for the observed balance deficits in COPD. Compared with age-matched controls, individuals with COPD demonstrated reductions in all balance control subsystems and slower reaction times in response to external perturbations. In this study, we also showed that deficits in balance in patients with COPD were associated with peripheral muscle weakness and reduced physical activity levels. These results informed the design of the final study of this thesis, a randomized controlled trial evaluating the addition of specific balance training to pulmonary rehabilitation for improving balance in patients with COPD. Preliminary results from this study suggest that the addition of thrice weekly balance exercises to a conventional pulmonary rehabilitation program is effective for optimizing gains in measures of functional balance and fall risk. The findings from the four studies included in this thesis support the need for incorporating balance assessment and treatment for at-risk patients with COPD, as part of their comprehensive management.

The purpose of this study was to establish an influence on static and dynamic postural control in sitting for voluntary arm movement for children with diplegic cerebral palsy. The investigation was fulfilled with control and experimental groups. The control group included ten healthy children and the experimental group included ten children with cerebral palsy. The age of the children was from 10 to 13 years. Subjects had to perform the same task with a single arm for four times. Every time the demands of postural control were increasing – the distance between objects and outward stability was changing. Task performing time was measured and visual estimation of the quality of postural control was done. The study showed that children with cerebral palsy performed the task slower than healthy ones (P < 0.05). The task performance time in the experimental group increased depending on growing distance between objects (p <0.05) and increased depending on decreasing outward stability (p < 0.05). The task’s time in the control group increased only when the distance was increasing between objects (p < 0.05), though when outward stability was decreasing the task’s performance time decreased (p < 0.05). A connection between task’s performance speed in standard conditions and task’s performance speed when the distance between objects was increased (r = 0.8), outward stability was decreased (r = 0.79), the distance between objects was increased and outward stability was decreased (r = 0... [to full text]

Preliminary evidence suggests that balance deficits constitute an important secondary impairment in individuals with chronic obstructive pulmonary disease (COPD). The main objective of this thesis was to describe balance impairment and fall risk in individuals with COPD and to examine interventions for improving balance and reducing fall risk in the context of pulmonary rehabilitation. The first study of this thesis showed that falls are common in patients with COPD and that fallers are characterized by impairments in standard clinical balance measures, such as the Berg Balance Scale and Timed Up and Go. In the second study, we found that the exercise component of conventional pulmonary rehabilitation has only modest effects on balance and fall risk in COPD, highlighting the need to examine the role of balance-specific training for these patients. The third study of this thesis identified the postural control subsystems most responsible for the observed balance deficits in COPD. Compared with age-matched controls, individuals with COPD demonstrated reductions in all balance control subsystems and slower reaction times in response to external perturbations. In this study, we also showed that deficits in balance in patients with COPD were associated with peripheral muscle weakness and reduced physical activity levels. These results informed the design of the final study of this thesis, a randomized controlled trial evaluating the addition of specific balance training to pulmonary rehabilitation for improving balance in patients with COPD. Preliminary results from this study suggest that the addition of thrice weekly balance exercises to a conventional pulmonary rehabilitation program is effective for optimizing gains in measures of functional balance and fall risk. The findings from the four studies included in this thesis support the need for incorporating balance assessment and treatment for at-risk patients with COPD, as part of their comprehensive management.

Movement of different body segments is an essential component for the control of postural stability. Notably, balance impairment has been reported in individuals with chronic low back pain. Various impairments that are likely to affect postural control have been reported in this population, including proprioceptive deficits and altered control of movement at the lumbopelvic region. Although little is known about how movement of the lumbar spine contributes to postural control, spinal movement is likely to be part of the movement strategy when the multisegmental nature of the human body configuration is taken into consideration. The overall objective of this thesis was to investigate the changes in postural stability in individuals with chronic LBP, and the association with altered movement control at the lumbar spine. The control of postural stability was examined with different postural challenges while standing on either a flat surface or a short base. A short base was used to force the subjects to use a “hip strategy”; movement at the lumbopelvic region for postural correction. Kinematics of different body segments including the lumbar spine and hip were recorded to study the movement of the lumbopelvic region. In addition, ground reaction force data were collected with a force platform system to examine postural adjustments during various postural tasks. The studies showed that people with chronic low back pain have difficulty maintaining stance, with increased risk of overbalancing when standing on a short base without any perturbation. Altered motion of the lumbar spine was evident during both expected and unexpected postural perturbations, which indicated impairment of both anticipatory and feedback control of lumbar motion in individuals with chronic low back pain. In addition, subjects took longer to regain postural stability and made more postural adjustments during the recovery period after expected and unexpected perturbations. Together, the studies suggested significant contribution of changes in lumbar motion to postural impairment in people with chronic low back pain. In summary, these findings provide further evidence that spinal movement plays a critical role in the maintenance of postural stability, and altered control of movement affects the quality of postural control in individuals with chronic low back pain.

Estudos prévios têm mostrado que a resposta postural automática pode ser influenciada por processamentos corticais associados com aprendizagem, experiência prévia e dica prévia. No entanto, pouco se sabe sobre como as respostas posturais de idosos são moduladas através de diferentes informações contextuais. O presente estudo objetivou investigar como a combinação de diferentes informações de contexto, dadas por experiência com tentativas prévias e dicas sobre aspectos temporais e espaciais de uma perturbação iminente, modulam respostas reativas em indivíduos idosos em comparação a adultos jovens. A tarefa consistiu em manter a postura ereta em resposta à rotação da base de suporte nos sentidos de dorsi ou plantiflexão do tornozelo, com amplitude e velocidade fixas. No Experimento 1 adultos jovens e idosos foram submetidos a quatro condições experimentais, resultantes da combinação de dica por indicação visual do sentido de rotação e de sequência de rotações, as quais eram feitas de forma aleatória ou repetitiva. No Experimento 2 foram oferecidas dicas sobre direção e/ou tempo de rotação da plataforma. Os resultados indicaram séries de tentativas com mesma direção de rotação induziram menor oscilação do centro de pressão e menor ativação muscular, enquanto que séries aleatórias induziram menor latência de ativação muscular. Dica temporal induziu latências mais curtas de ativação muscular, e dica sobre direção de perturbação induziu respostas musculares de menor magnitude (efeito observado apenas no Experimento 1). Não foi observado efeito diferencial de dicas entre os grupos etários. Os resultados sugerem que informações contextuais modulam respostas posturais reativas, e que o controle postural em indivíduos idosos é beneficiado por informações contextuais de forma similar a adultos jovens / Previous studies have shown that automatic postural responses can be influenced by cortical processing associated with learning, prior experience, and precue. However, scarce behavioral evidence has been provided about how postural responses are modulated by different contextual information in the elderly. The present investigation aimed at evaluating how different contextual information through prior experience and precueing about direction and/or time of basis of support rotation modulate reactive postural responses of elderly. The task consisted of recovering stable upright body balance in response to rotation of the support basis, inducing dorsi or plantar flexion with fixed amplitude and velocity. In Experiment 1 young and elderly people performed four experimental conditions resulting from combination of visual precue about direction of rotation and prior experience through repetitive or random sequences of trials. In Experiment 2 participants were provided with precueing about direction and/or time of platform rotation. Results showed that series of trials with the same direction of rotation induced decreased center of pressure oscillation and muscular activation, whereas random series induced shorter latencies of muscular activation. Precueing about time of platform rotation induced shorter latencies of muscular activation, and precueing about direction of rotation induced decreased muscular activation (effect observed in Experiment 1 only). No differential effect of precueing was observed between age groups. Results suggest that contextual information modulates reactive postural responses, and that elderlys reactive postural responses are benefited by contextual cues in a similar way as young adults responses

A Sociedade Internacional de Continência (ICS) define que toda queixa de perda involuntária de urina é considerada incontinência urinária (IU), sendo que a IU é um processo natural do envelhecimento que afeta de 25 a 45% das mulheres brasileiras. Portadores de IU podem apresentar alterações no controle postural, pois a musculatura do assoalho pélvico é responsável pela estabilização das estruturas da pelve, possuindo assim íntima relação com o controle postural estático. Em virtude disto, o presente estudo tem por objetivo comparar o controle postural de mulheres idosas com relato de perdas urinárias e idosas continentes, nas condições de olhos abertos, supressão da visão e durante teste de dupla tarefa cognitiva e visual. Trata-se de um estudo do tipo observacional de caráter transversal, quantitativo realizado com 46 mulheres idosas, sendo 26 com incontinência urinária com média de idade 68,31 ± 5,79 anos e 20 continentes com média de idade 69,3 ± 6,87 anos. Foi utilizado um questionário de anamnese, para identificar aspectos gerais de saúde das idosas, onde incluía auto relato de perda urinária. A análise do controle postural foi realizada utilizando-se uma plataforma de força para a obtenção dos dados referentes ao centro de pressão (COP). As idosas foram avaliadas nas situações: olhos abertos, olhos fechados e teste de dupla tarefa stroop color. Os dados foram analisados utilizando-se o programa estatístico SPSS 17.0. A normalidade foi verificada através do teste de Shapiro-Wilk e após, realizado teste t de Student e o nível de significância adotado foi de 5%. Os resultados não apresentaram diferenças estatisticamente significativas em todas as variáveis do COP na situação de olhos abertos, nem nas variáveis COPap e COPml de olhos fechados bem como no COPap, COPml e COPvel na dupla tarefa. E as variáveis COPvel e COPelp na situação de olhos fechados e COPelp na dupla tarefa, apresentaram diferenças estatisticamente significativas com p<0,05. Concluiu-se que as mulheres idosas com relato de perdas urinárias apresentaram um pior desempenho do controle postural estático no que se refere a velocidade média de oscilação e a área de oscilação, quando comparadas as idosas continentes. / The International Continence Society (ICS) defines that every complaint involuntary loss of urine are considered urinary incontinence (UI). The UI is a natural process of aging and affects 25-45% of Brazilian women. IU carriers may show changes in postural control, because the pelvic floor muscles is responsible for stabilization of pelvic structures, thus having intimate relationship with the static postural control. This study analyzed and compared the postural control of elderly women with urinary incontinence and continent. The data collection conditions were with eyes open, suppression of vision and with dual cognitive and visual task. It is an observational study of transversal, quantitative conducted with 46 elderly women, 26 UI with a mean age 68.31 ± 5.79 years and 20 continent with a mean age 69.3 ± 6.87 years. The anamnesis questionnaire was used to identify general aspects of health of older, which included urinary loss self-reported. The analysis of postural control was performed using a force plate to obtain data on the center of pressure (COP). The elderly were evaluated in situations: eyes open, eyes closed and dual task Stroop color test. Data were analyzed using SPSS17.0 statistical software, data normality was verified using the Shapiro-Wilk test and after, performed t Student test, and Statistical significance was set at a p-value< 0.05. The results no significant differences for all variables to COP in open eyes, COPap and COPml in closed eyes situations, and COPap, COPml e COPvel in dual task. The results were statistically significant with p<0,05 for variables COPvel and COPelp in closed eyes situations and COPelp in dual task. It was concluded that older women reporting urinary losses showed a worse performance of the static postural control COPvel and COPelp in relation to continent women.

Orientador: José Angelo Barela / Banca: Sérgio Tosi Rodrigues / Banca: Ronald Dennis Paul Kenneth Clive Ranvaud / Banca: Renato de Moraes / Banca: Dora S. Fix Ventura / Resumo: Três experimentos foram propostos para investigar os ajustes dinâmicos nos pesos de múltiplas fontes de informação sensorial. O primeiro experimento investigou as respostas posturais de 18 bebês frente às mudanças abruptas na amplitude do estímulo visual. Eles permaneceram sentados dentro de uma sala móvel por 8 tentativas de 60 segundos cada. A sala ficou estacionária na primeira tentativa. Nas sete tentativas seguintes, a sala foi oscilada em 0,2 Hz com amplitude de 1,1 cm, com exceção da quinta tentativa, na qual a sala foi movimentada em amplitude mais alta (3,2 cm). Os resultados mostraram fraco acoplamento entre informação visual e oscilação corporal. Contudo, a variabilidade de oscilação foi maior em bebês experientes no sentar independente. Nós concluímos que bebês não foram capazes de se adaptar às pequenas alterações na amplitude do estímulo visual. O segundo experimento investigou como o controle postural de crianças se adapta às abruptas mudanças no ambiente visual. Trinta crianças de 4, 8 e 12 anos de idade e dez adultos, permaneceram em pé dentro de uma sala móvel. A situação experimental foi similar a do primeiro experimento exceto que a amplitude baixa da sala foi de 0,5 cm e a amplitude alta foi de 3,2 cm. As respostas posturais de crianças mais velhas e adultas diminuíram mais para o estímulo visual do que aquelas de crianças mais novas quando a amplitude da sala foi aumentada. A variabilidade de oscilação diminuiu com a idade e foi maior durante a tentativa de alta amplitude. Crianças tão novas quanto 4 anos de idade já têm desenvolvida a capacidade de rapidamente diminuir a influência do estimulo visual. Contudo, os mais altos valores de ganho e variabilidade residual para crianças de 4 e 8 anos de idade sugerem que elas não apresentam respostas totalmente calibradas ao nível adulto... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Three experiments were designed to investigate the dynamic adjustments in the weights of multiple sensory modalities. The first experiment investigated the postural responses of 18 infants to abrupt changes in the amplitude of visual stimulus. They seated inside of a moving room for eight trials of 60 sec apiece. The room was stationary in the first trial. In the following seven trials, the room oscillated at 0.2 Hz with amplitude of 1.1 cm, with the exception of the fifth trial, in which the room moved at higher amplitude (3.2 cm). The results showed weak coupling between visual stimulus and body sway. However, sway variability of experienced sitters was higher in the high-amplitude trial. We concluded that infants were not able to adapt to low range of visual stimulus amplitude. The second experiment investigated how children’s postural control adapt to abrupt changes in the surrounding visual environment. Thirty children from 4-, 8- and 12-year olds and ten adults stood upright inside of a moving room. The experimental set-up was similar to the first experiment except that low-amplitude was 0.5 cm and high-amplitude was 3.2 cm. Body sway responses of old children and adults downweight more to the visual stimulus than young children when the amplitude of the room increased. Sway variability decreased with age and was largest during the high-amplitude trial. Children as young as four years of age have already developed the adaptive capability to quickly downweight visual information. However, the higher gain values and residual variability observed for the 4 and 8 year-old children suggest that they have not fully calibrated their response to the adult level. The third experiment investigated the postural responses of two sensory modalities measured simultaneously... (Complete abstract click electronic access below) / Doutor

xiii, 103 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / The purpose of this dissertation was (1) to investigate the effects of dual task conditions on the development of postural control during gait in typically developing children while walking and obstacle crossing, and (2) to investigate the attentional requirements of gait in children with cerebral palsy (CP). Forty younger and older typically developing (YTD and OTD) children and 10 children with CP performed a gait task with and without a concurrently auditory Stroop task. Gait and cognitive performance were measured. In study 1, dual task interference with gait performance was found in YTD and OTD children, but not in healthy young adults (HYA). In general, gait performance decrements under dual task contexts were greater in YTD than OTD children, whereas cognitive performance decrements during dual tasking were not different between the two groups of children. Dual task interference was lowest in HYA and highest in YTD children when compared among groups. As the difficulty of the gait task was increased, dual task affects on cognitive performance were now found in YTD and OTD children, but not HYA. In study 2, there were significant differences in dual task interference affecting gait performance in all groups of children. When performing the gait task with a concurrent auditory Stroop task, OTD children showed greater dual-task costs than children with CP for accuracy, but children with CP demonstrated greater dual-task costs than OTD and YTD children for medial Center of Mass-Ankle-joint-center inclination angle. This increased medio-lateral inclination angle in dual task situations has also been seen in older adults with balance deficits and may be associated with an increased risk for falls. YTD children showed dual-task costs in a slowing of gait velocity and stride time, a safer strategy than that used by children with CP. The lower cognitive performance during dual tasking for OTD children suggests that they allocate greater attention to maintain gait stability, whereas YTD children and children with CP do not. In addition, children with CP use a behavior that may increase their risk of falls in complex environments. This dissertation includes unpublished co-authored material. / Committee in charge: Marjorie Woollacott, Chairperson, Human Physiology; Paul van Donkelaar, Member, Human Physiology; Li-Shan Chou, Member, Human Physiology; Paul Dassonville, Outside Member, Psychology

The primary goal of this research was to explore attentional factors contributing to normal balance control and to determine how age-related changes in these factors constrain balance in the aging adult. Though previous research has demonstrated attentional interference between postural control and performance of cognitive tasks in young (YA) and older adults (OA), the mechanisms contributing to interference have not been identified. This study utilized as a cognitive task, a visual working memory task (the change detection task), which identified the short term working memory (or attentional) capacity limits of participants. Participants were asked to perform the cognitive task (determining a change in the color of squares in a first vs. second memory array) either in isolation or with postural tasks of increasing complexity, including quiet sitting (control), quiet stance in isolation, quiet stance (but intermixed with support surface perturbations), and support surface perturbations. YA showed a significant decline in working memory capacity between the control and perturbation condition (p<0.01) but no change in postural performance between single and dual task conditions, as determined by increased steps in response to perturbations (p<0.33). In a second set of experiments, the performance of OA was compared to YA. Results showed that OA had reduced working memory capacity on the change detection task compared to YA even in the control condition (YA: 2.8±0.6 items; OA: 1.8±0.7; p<0.001). OA showed an even greater decline than YA in memory capacity in the dual task condition (p<0.001), along with difficulty regaining balance following perturbations, evidenced by significant increases in up on toes (p<0.05) and stepping strategies (p<0.05). These results suggest that visual working memory (for simple features) and postural control share a common attentional resource that is limited and that postural control is favored over the cognitive task in YA. In OA, attentional capacity was significantly reduced and both postural and cognitive tasks were impaired in the dual task condition, suggesting that with aging even simple cognitive tasks can negatively affect balance under challenging postural conditions.

O controle postural vem sendo estudado há algum tempo com o intuito de entender o complexo funcionamento do sistema de controle postural, além de servir para evitar quedas em idosos. As quedas são eventos que ocorrem em aproximadamente um terço da população idosa e podem levar a consequências muito graves, o que dá importância para o tema. A dupla-tarefa com interferência cognitivo-motora pode afetar o desempenho dos idosos na tarefa de manter o equilíbrio e aumentar o risco de quedas. Logo, o objetivo desse estudo foi avaliar o efeito de tarefas cognitivas sobre o desempenho em tarefas de controle motor estático e dinâmico em adultas jovens (n=25) e idosas caidoras (n=20) e não-caidoras (n=21). Foram avaliados o controle postural estático em dois tipos de superfície (estável e instável) e também o desempenho na tarefa de marcha com transposição de obstáculos, durante dois tipos de tarefas cognitivas (teste de Stroop e contagem regressiva em etapas de três). ANOVAs de dois fatores foram usadas para avaliar as diferenças entre grupos e condições. O equilíbrio estático foi melhor para jovens em comparação com idosas, que não diferiram entre caidoras e não-caidoras. A tarefa de contagem regressiva piorou o equilíbrio, principalmente nas idosas. Na tarefa de ultrapassagem de obstáculos, a velocidade das idosas caidoras foi menor, mesmo sem tarefa cognitiva, sendo que a tarefa cognitiva influenciou o desempenho das idosas não-caidoras e jovens. As distâncias verticais na transposição do obstáculo foram maiores para o grupo de idosas caidoras, diferente do esperado, denotando uma segurança maior na tarefa nesses indivíduos e uma menor chance de cair nesses indivíduos. É possível que esse resultado seja relacionado ao medo de cair nesses idosas, o que levou os mesmos a realizarem uma tarefa mais cautelosa na transposição do obstáculo. Com relação às distâncias horizontais, as jovens afastaram mais o pé do obstáculo, denotando maior capacidade nessa tarefa que idosas não-caidoras e caidoras, não havendo efeito da tarefa cognitiva. Os resultados indicam que o desempenho em tarefas de controle postural estático e dinâmico é pior em idosas, sem grandes diferenças entre caidoras e não-caidoras. Na tarefa de transposição do obstáculo, as idosas optaram por uma tarefa mais cautelosa, mesmo quando nenhuma tarefa cognitiva era solicitada, ao passo que a tarefa cognitiva levou as jovens a realizar estratégia semelhante. O medo de cair que acomete o idoso pode ter levado a estratégias mais cautelosas. Conclui-se que o as tarefas cognitivas afetam o desempenho no controle postural estático em jovens e idosas e afetam o desempenho da tarefa dinâmica em jovens, principalmente. Durante a execução da tarefa de marcha com obstáculo, as idosas assumiram uma estratégia mais segura, possivelmente pelo medo de cair. Somente o teste de contagem regressiva aplicou demanda cognitiva suficiente para afetar a realização das tarefas motoras, enquanto que o teste de Stroop ajudou a tarefa motora em alguns casos. / Postural control has been studied in the last years to understand the hard behavior of the postural control system and to find ways to prevent falls in elderly. One third of the elderly people experiences falls during the live and falls can lead to serious consequences, being an important issue to study. Cognitive-motor interference in dual-task conditions can affect balance tasks performance on elderly and increase the risk of falls. Thus, this study aims to evaluate the effect of cognitive tasks on static and dynamic motor control tasks performances in young women (n = 25) and fallers (n = 20) and non-fallers (n = 21) older women. Static postural control in two surface conditions (stable and unstable) and obstacle negotiation task during walking were evaluated, while the subjects were performing two different cognitive tasks (Stroop task and counting backwards on steps of three) and without any cognitive task. Were performed ANOVAs with two factor to test differences between groups and conditions. Static balance was better in younger compared to old-aged, and non-fallers and fallers did not differ between themselves. Counting backward cognitive task impaired the balance especially in elderly. During obstacles negotiation tasks, the mean velocity was lower for fallers than the other groups, even without cognitive task. Cognitive tasks impaired performance of non-fallers and younger groups. Vertical distances on obstacle negotiation were higher for the fallers group, different than we expected. It means that this group performs the task safer than the others perform and has lower chance of falling. It is possible that these results are related to the elderly fear of falling, which led them to conduct a more cautious task during obstacle negotiation. Regarding to horizontal distances, young people distance more their foot from obstacle, showing increased capacity in this task than non-fallers and fallers, with no effect of cognitive task. Results indicate that static and dynamic performance on postural control tasks is worse in the elderly, without many differences between fallers and non-fallers. In obstacle negotiation task, elderly have opted for a more cautious task, even when no cognitive task was requested, while the cognitive tasks lead young people to perform similar strategy. Fear of falling that affect elderly people has led them to take more cautious strategies. We conclude that the cognitive tasks affect static postural control performances in young and old groups and affect dynamic task performance mainly in the young group. During the obstacle negotiation task, elderly have taken a safer strategy, possibly due to fear of falling in this task. Only the counting backwards task applied a sufficient cognitive demand to affect the proposed motor tasks while the Stroop task improved the performances for some variables.