Strategies Adopted by Stroke Patients to Maintain Balance in Dynamic Tasks in a Video Game.

Postural instability affects motor tasks after a stroke. We investigated the strategies used to maintain balance during quiet standing posture and dynamic tasks in a video game. Sixteen stroke volunteers (12 males, 56 ± 9 years, post-stroke time 35 ± 10 months) and sixteen matched healthy volunteers had their biomechanical data collected to obtain the variables: center of mass, base of support, margin of stability, and weight symmetry. Healthy individuals and stroke patients showed similar dynamic stability. However, they adopted different motor strategies to achieve this: healthy individuals increased their base of support as they progressed to more challenging tasks, and stroke volunteers maintained the same base. The margin of stability of stroke volunteers was correlated with the MiniBEST scale.

Estabilidade dinâmica de pessoas com AVE durante o movimento de cabeceio simulado em um jogo digital / Estabilidad dinámica de personas con ACV durante el movimiento de cabeceo simulado en un juego digital / Dynamical stability of post-stroke volunteers during soccer headers simulated by a digital game

RESUMO A estabilidade postural é um objetivo de tratamento na fisioterapia que pode ser alcançado por meio de exercícios de transferência de peso bilateral. Os jogos digitais surgem como alternativa para execução desses exercícios, mas sua avaliação ainda necessita de aprimoramento. Propõe-se aqui o uso de variáveis biomecânicas para verificar o comportamento da estabilidade postural dinâmica durante um movimento de cabeceio, simulado por um jogo digital com diferentes exigências de velocidades. Para isso, 16 voluntários pós-acidente vascular encefálico (AVE) - 12 homens e 4 mulheres, com idade média de 56 anos - e 16 hígidos pareados por sexo e idade participaram da coleta experimental, na qual eles foram submetidos ao jogo digital "cabeceio", que tem cinco níveis de velocidade, do mais lento ao mais rápido, com duração de 30 segundos cada. A partir dos sinais cinemáticos foi possível calcular os indicadores de interesse, a área da base de suporte e a margem de estabilidade, definida como a menor distância entre as bordas da base de suporte e a projeção vertical do centro de massa (CM) extrapolado, que considera a velocidade do CM. Os valores da base de suporte não apresentaram diferenças entre os níveis de velocidade do jogo, mas sim entre grupos. A margem de estabilidade não diferiu entre níveis e grupos. Os níveis de velocidade do jogo, possivelmente, não estimularam os voluntários a buscar estratégias diferentes para manter a estabilidade, como dar um passo, mas os fizeram adotar bases de suporte diferentes, sendo que indivíduos com AVE adotaram uma base de suporte menor do que a dos hígidos.

RESUMEN La estabilidad postural es el objetivo del tratamiento en fisioterapia que puede lograrse mediante ejercicios de traslado de peso bilateral. Los juegos digitales son una alternativa para realizar estos ejercicios, pero aún necesita mejorar su evaluación. Se propone el uso de variables biomecánicas para verificar el comportamiento de estabilidad postural dinámica durante el movimiento de cabeceo, simulado por un juego digital con diferentes requerimientos de velocidad. Para ello, 16 voluntarios pos-accidente cerebrovascular (ACV) -12 hombres y 4 mujeres, con edad media de 56 años- y 16 individuos sanos pareados por sexo y edad participaron de la recolección experimental, en la que fueron sometidos al juego digital "cabeceo", que cuenta con cinco niveles de velocidad, del más lento al más rápido, con una duración de 30 segundos cada uno. A partir de las señales cinemáticas fue posible calcular los indicadores de interés, el área de base de apoyo y el margen de estabilidad, definido como la menor distancia entre los bordes de la base de apoyo y la proyección vertical del centro de masa (CM) extrapolado, que considera la velocidad del CM. Los valores de la base de apoyo no mostraron diferencias entre niveles de velocidad de juego, pero sí entre grupos. El margen de estabilidad no difirió entre niveles y grupos. Los niveles de velocidad de juego posiblemente no animaron a los voluntarios a buscar diferentes estrategias para mantener la estabilidad, como dar un paso, pero les hicieron adoptar diferentes bases de apoyo, llevando a los individuos con ACV a emplear una base de apoyo menor que la de los individuos sanos.

ABSTRACT Postural stability is a goal of physical therapy treatment which can be achieved by bilateral weight transfer exercises. Digital games come as an alternative to performing these exercises, and their evaluation still needs improvement. We proposed using biomechanical variables to assess postural stability behavior. We aimed to investigate dynamic postural stability during soccer headers simulated by a digital game with different speed requirements. For this, 16 post-stroke volunteers (12 men and 4 women with a mean age of 56 years) and 16 healthy volunteers, paired by sex and age, participated in the experimental collection, in which they were subjected to the digital game "Cabeceio" (Soccer Heading), which has five speed levels, from slowest to the fastest, lasting 30 seconds each. From the kinematic signals, we could estimate our indicators of interest: the area of the base of support and the margin of stability, the latter defined as the smallest distance between the edges of the base of support and the vertical projection of the extrapolated CM, considering CM speed. The values of the base of support failed to differ between game speed levels, but did so between groups. The margin of stability failed to differ between levels and groups. The speed levels of the game possibly failed to encourage volunteers to pursue different strategies to maintain dynamic stability, such as taking a step. Although they maintained different support bases, post-stroke individuals adopted a smaller base of support than healthy ones.

Influence of feet position on COP measures in post-stroke patients in quiet standing.

BACKGROUND: Foot placement is an important methodological parameter in experiments for analyzing the behavior of the center of pressure (CoP) duringquiet standing. In the case of stroke patients, this is a relevant issue, as the standardized position, usually adopted is not ecological. RESEACH QUESTION: Do between-limb synchronization, weight-bearing symmetry, and amplitude of the postural sway of post-stroke individuals differ between standardized and comfortable foot positions during quiet standing? METHODS: A total of 36 volunteers (20 with stroke and 16 healthy) stood barefoot, for 60 s, on two force plates with feet in a comfortable and standardized position (14° of external rotation and heels 17 cm apart). Three trials were performed in each position, and the average values obtained were analyzed. RESULTS: The comfortable position adopted by stroke individuals was characterized by heels kept 17 cm apart and with 21° of external rotation. None of the measures of the healthy group were influenced by feet position. In the stroke group, the lag to maximal between-feet correlation in the mediolateral direction (ML ρmax lag) was higher (0.45 s) and the weight-bearing symmetry was better in the comfortable (38%) than in the standardized conditions (0.19 s and 32%, respectively). Neither the other CoP measures nor the intra-subject variability was sensitive to feet position. SIGNIFICANCE: The assumption that standardization leads to reduced variability might not be valid to the post-stroke and healthy individuals age around 55 years. Therefore, adoption of a comfortable condition might be advantageous, once it allows for a more practical and realistic evaluation of postural control.