Browsing by Subject "Balance control"
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Item Assessment of turning performance and muscle coordination in individuals post-stroke(2020-04-29) Lewallen, Lindsey Kate; Neptune, Richard R.Turning is an important activity of daily living and often compromised post-stroke. The fall rate for post-stroke individuals while turning is nearly four times as high compared to healthy adults, with most falls resulting in injury. Thus, there is a need for evidence-based rehabilitation targets to improve turning performance for post-stroke individuals. To produce well-coordinated movements, muscles can be organized into muscle modules (i.e., groups of co-excited muscles). Post-stroke these modules can be merged, leading to impaired muscle coordination and walking performance. However, the relationship between impaired coordination and turning performance is not well understood. Thus, the purpose of this study was to analyze the influence of impaired muscle coordination (i.e., merged modules) on turning performance (i.e., time to complete a turn, number of steps required to complete a turn, smoothness of performing the turn and balance control during a turn). Post-stroke individuals and healthy controls performed three tasks including overground straight line walking, a 90-degree turn and a 180-degree turn. The number of muscle modules during straight line walking were determined using non-negative matrix factorization. As few as two modules were found in post-stroke individuals. Differences in turning performance were only seen in the 180-degree turning performance measures. Those with two modules took longer to turn, used more steps and had less smooth movement. These results suggest obtaining independent modules should be an important aim in locomotor therapies aimed at improving turning performance. In addition, the time it takes to complete a 180-degree turn may be a useful clinical assessment measure of the degree of muscle coordination impairment post-stroke.Item The influence of cognitive load on balance control during walking(2021-04-19) Small, Gabriella Hodges; Neptune, Richard R.Maintaining dynamic balance is essential during walking, with foot-placement playing a critical role. Situations requiring increased cognitive attention may impair an individual’s ability to actively control their balance. While dual-task studies have analyzed walking-while-talking conditions, few studies have focused on how cognitive loads impact balance control during steady-state walking and more difficult motor tasks, such as walking with foot-placement perturbations. Individuals recover from a loss of balance using an ankle or hip strategy, but how cognitive loads effect these recovery strategies remains unknown. The overall goal of this research was to investigate the influence of cognitive loads on balance control using two aims. The first aim assessed how individuals prioritize cognitive resources and control balance during steady-state walking with increasing cognitive loads. Aim 2 investigated how individuals prioritize cognitive resources to control their balance during dual-task walking while experiencing foot-placement perturbations. Fifteen young healthy adults performed a cognitive single-task condition (spelling-while-standing) and four treadmill walking conditions (no cognitive load, attentive listening, spelling short words backwards and spelling long words backwards), each performed during steady-state (Aim 1) and perturbed conditions (Aim 2). No specific task-prioritization instructions were given. During the perturbed trials, medial and lateral foot-placement perturbations were applied before heel-strike during random steps. Aim 1 showed that cognitive performance did not change between single- and dual-task conditions, but balance control decreased during the spelling dual-tasks. Aim 2 found that cognitive performance decreased between unperturbed and perturbed conditions. While balance control decreased during perturbed relative to unperturbed walking, the additional cognitive load had little effect during the perturbations. Lastly, the balance recovery strategy was unaffected by the addition of a cognitive load. The results from Aim 1 highlight that in steady-state walking, balance control decreases during treadmill walking with increased cognitive loads, but cognitive performance does not change, suggesting that participants prioritized cognitive performance over balance control. In contrast to steady-state walking, Aim 2 found that individuals prioritize their balance over cognitive task performance when faced with foot-placement perturbations. Overall, these results emphasize the flexibility of task-prioritization in young adults and provide a foundation for future studies analyzing neurologically impaired populations