Maintenance Of Postural Control Research Articles

What Is the Role of Sustained Visual Attention in the Maintenance of Postural Control in Young Adults?

Dual tasks requiring sustained visual attention and upright stance are common, yet their impact on standing balance is not well understood. We investigated the role of visual attention in the maintenance of postural control, using the multiple-object tracking (MOT) task. Healthy young adults (n = 12) performed the MOT task at three object movement speeds while seated or standing. MOT performance was assessed using tracking capacity (k). Metrics calculated to assess mediolateral (ML) and anterior-posterior (AP) postural control included: maximum difference between CoM and CoP position (CoM-CoP Max), root mean square distance for center of pressure and center of mass position (CoP and CoM RMS distance), and correlation between CoM and CoP time series signals (CoM/CoP correlation). As predicted, k decreased significantly as object movement speed increased for both standing and seated conditions. Object movement speed also significantly affected AP CoM-CoP Max in seated conditions (p = .021) and AP CoM/CoP correlation for standing conditions (p = .002). The results demonstrate utility of the MOT task in understanding the role of visual attention in postural control, even though healthy young adults were able to compensate for the addition of a sustained visual attention task, with minimal deficits to postural control.

Balance on different unstable supports: a complementary approach based on linear and non-linear analyses.

Maintenance of postural control is a complex task that requires the integration of different sensory-motor processes. To improve postural control, balance training is often implemented using unstable surfaces. Little is known, however, about how different surfaces compare in terms of postural control strategy. Non-linear dynamical system analysis, like recurrent quantification analysis (RQA) applied to the center of pressure (CoP) trajectory, represents a useful tool in this respect. The aim of this study is to investigate the effects of different unstable supports on the CoP trajectory through a complementary approach based on linear and non-linear analyses. Seventeen healthy adults performed barefoot single-leg balance trials on a force plate and on three different balance training devices (soft disc, foam pad, and pillow). Sets of parameters were extracted from the CoP trajectories using classical stabilometric analysis (sway path, mean velocity, root mean square) and RQA (percent recurrence and determinism, maximum line length, entropy). Both classical and RQA analyses highlighted significant differences between stable (force plate) and unstable conditions (p < 0.001). Conversely, only classical stabilometric parameters showed significant differences among the considered balance training devices, indicating that the different characteristics of the devices do not influence the dynamic/temporal structure of the CoP trajectory. Analysis of the center of pressure trajectory during single-leg standing on three different balance training devices and on a rigid surface using both linear and non-linear techniques.

Age-Related Changes in Postural Control in Physically Inactive Older Women.

The maintenance of postural control is influenced by the complexity of a given task. Tasks that require greater attention and cognitive involvement increase the risk of falls among older adults. The aim of the present study was to evaluate the adaptation of the postural control system to different levels of task complexity in physically inactive young and older women. A cross-sectional study was conducted with adult women classified as physically inactive based on the results of the International Physical Activity Questionnaire. The participants were 27 young (20-30 years of age) and 27 older (60-80 years of age) women. Sway velocity of the center of pressure in the anterior-posterior and medial-lateral directions was calculated using a force plate under 6 conditions: standing directly on the force plate or on a foam placed over the force plate, eyes open or closed, and dual-task complexity with and without the foam. A 2-way analysis of variance revealed that sway velocity increased in both groups when the task conditions were altered. The older women exhibited significantly greater sway velocity compared with the young women on all tasks. However, the patterns of postural control adaptation to the different levels of complexity were similar among all participants. In this study, the adaption of the postural control system to different levels of task complexity did not differ between physically inactive young and physically inactive older women. However, the physically inactive older women exhibited greater sway velocity compared with the young women.

Effects of Plantar Flexor Muscles Fatigue on Postural Control during Quiet Stance and External Perturbation in Healthy Subjects

The maintenance of postural control is a key component in dynamic physical activity, especially during muscle fatigue and against external forces. Despite many studies in this field, there is no consensus regarding the effects of plantar flexor muscles fatigue on postural control during different postural tasks. To evaluate the effects of plantar flexor muscles fatigue on postural control during quiet stance and external perturbation in healthy subjects. Twenty four healthy individuals (20-35 years) participated this interventional study. The foot center of pressure data was measured using a single force platform, and then the postural control parameters, including the center of pressure displacement and velocity in the anterior-posterior and medial-lateral direction and also path length calculated under two conditions; quiet and perturbed stance, before and after plantar flexor muscles fatigue. The statistical analysis demonstrated that mean displacement and velocity of the center of pressure in the anterior-posterior direction and also path length increased after the fatigue protocol in the perturbed condition. However, fatigue had no significant effects on postural control parameters in the quiet standing condition. These results indicated that the effects of muscle fatigue on postural control depend on the difficulty of the task and the relevance of proprioceptive information. The postural control system appears to use distinct control strategies in different situations such as quiet and perturbed stance conditions, and these strategies may be differentially altered by fatigue. In conclusion, due to the potential risk of loss of balance, it is important to take the role of plantar flexor muscle fatigue into account during more difficult postural tasks.

Effects of astigmatic axis orientation on postural stabilization with stationary equilibrium

We evaluated 15 healthy participants by assessing their maintenance of postural control while standing on a platform stabilometer for 1 min under the following conditions: eyes open; eyes open with + 3.00 D on both eyes on same directions (45, 90, 135, 180 degree axis); right eye on 45 degree axis and left eye on 135 degree axis (inverted V-pattern), and right eye on 135 degree axis and left eye on axis 45 degree axis (V-pattern). The differences in the linear length, area and maximum velocity of center of pressure during postural control before and after the six types of positive cylinder-oriented axes were analyzed. Comparing the antero-posterior lengths and antero-posterior maximum velocities, there were significant differences between the V-pattern condition and the six other conditions. Astigmatic defocus in the antagonistic axes conditions, particularly the V-pattern condition, affects postural control of antero-posterior sway (143/150).

Eletromiografia e controle postural em atletas de handebol e praticantes de musculação

Introdução: Uma forma de avaliar o controle postural, tanto unipodal como bipodal, é através da mensuração da atividade eletromiográfica de músculos de membros inferiores (bíceps femoral, reto femoral, vasto lateral, e gastrocnêmico medial). Objetivos: Comparar o controle postural eletromiográfico bipodal e unipodal de atletas de handebol do sexo feminino com praticantes de musculação do mesmo sexo. Metodologia: O controle postural foi avaliado através do teste de permanecer o mais imóvel possível durante 30 segundos, em apoio bipodal e unipodal direita. Resultados: As atletas de handebol obtiveram maior ativação no músculo reto femoral na condição bipodal, e também para os quatro músculos avaliados na condição unipodal, enquanto que, para as praticantes de musculação a maior ativação foi encontrada apenas para os músculos reto femoral e gastrocnêmio medial na condição unipodal. Conclusão: É possível concluir, com base no presente estudo, que a prática de modalidades esportivas distintas pode interferir, devido a especificidade da modalidade treinada, provocando alterações fisiológicas na manutenção do controle postural, avaliada através da eletromiografia.

Influência de tarefas cognitivas sobre o equilíbrio estático de indivíduos saudáveis

Introdução: O controle postural depende da ação integrada dos sistemas sensoriais e motores, e uma maior demanda atencional em situações de dupla-tarefa possivelmente acarreta maior oscilação postural. Objetivo: comparar a influência de tarefas cognitivas sobre o equilíbrio estático de indivíduos saudáveis. Materiais e métodos: estudo transversal realizado com 20 participantes adultos saudáveis. Os participantes foram submetidos a avaliação estabilométrica (olhos abertos e fechados) durante a execução de tarefas cognitivas (Stroop Test e contagem regressiva) e na situação controle (sem tarefa). Os deslocamentos do centro de pressão foram coletados e analisado. Resultados: Houve diferença significante dos efeitos obtidos na execução da tarefa matemática em comparação às demais situações (aumento da área de deslocamento e oscilações do centro de pressão). As demais comparações do tamanho do efeito não demonstraram significância. Conclusão: A execução de tarefas cognitivas influenciou o equilíbrio estático dos participantes. A tarefa matemática demonstrou maior influencia sobre o equilíbrio estático.

The Brain in Its Body: Motor Control and Sensing in a Biomechanical Context

Although it is widely recognized that adaptive behavior emerges from the ongoing interactions among the nervous system, the body, and the environment, it has only become possible in recent years to experimentally study and to simulate these interacting systems. We briefly review work on molluscan feeding, maintenance of postural control in cats and humans, simulations of locomotion in lamprey, insect, cat and salamander, and active vibrissal sensing in rats to illustrate the insights that can be derived from studies of neural control and sensing within a biomechanical context. These studies illustrate that control may be shared between the nervous system and the periphery, that neural activity organizes degrees of freedom into biomechanically meaningful subsets, that mechanics alone may play crucial roles in enforcing gait patterns, and that mechanics of sensors is crucial for their function.