Small Gabriella H, Neptune Richard R
Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, USA.
Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, USA.
Gait Posture. 2022 Jun;95:115-120. doi: 10.1016/j.gaitpost.2022.04.010. Epub 2022 Apr 15.
Maintaining dynamic balance is an essential task during walking, with foot-placement playing a critical role. Dual-task studies analyzing steady-state walking with cognitive loads have found healthy adults prioritize cognitive task performance at the expense of maintaining control of their balance. However, few studies have focused on the influence of cognitive loads on more difficult motor tasks, such as walking with unexpected foot-placement perturbations. Individuals often recover from a loss of balance using an ankle or hip strategy; however, how cognitive loads affect these balance recovery strategies remains unknown.
How do individuals prioritize cognitive resources and does the balance recovery strategy used change following mediolateral foot-placement perturbations during steady-state walking when performing cognitive tasks of increasing difficulty?
Fifteen young healthy adults walked during unperturbed and perturbed conditions with increasing cognitive loads (no cognitive load, attentive listening, spelling short words backwards and spelling long words backwards). No specific task-prioritization instructions were given. Medial and lateral foot-placement perturbations were applied prior to heel-strike during random steps.
Cognitive performance decreased between the unperturbed and perturbed conditions. While balance control decreased during perturbed relative to unperturbed walking, the additional cognitive load had little effect on balance control during the perturbations. Lastly, the balance recovery strategy used, as measured by peak joint moments at the ankle and hip, was unaffected by the additional cognitive loads.
Individuals appear to prioritize their balance control over cognitive performance when experiencing foot-placement perturbations and do not change their balance recovery strategy with the addition of a cognitive load. These results highlight the flexibility of task-prioritization in young adults and provide a foundation for future studies analyzing neurologically impaired populations.
在行走过程中保持动态平衡是一项至关重要的任务，其中足部放置起着关键作用。分析带有认知负荷的稳态行走的双任务研究发现，健康成年人会优先考虑认知任务的表现，而牺牲对平衡的控制。然而，很少有研究关注认知负荷对更具挑战性的运动任务的影响，比如在行走时遭遇意外的足部放置扰动。个体通常会使用踝关节或髋关节策略从平衡丧失中恢复；然而，认知负荷如何影响这些平衡恢复策略仍不清楚。
在执行难度不断增加的认知任务时，个体如何分配认知资源的优先级，以及在稳态行走过程中，当受到内外侧足部放置扰动后，所使用的平衡恢复策略是否会发生变化？
15名年轻健康的成年人在无扰动和有扰动的情况下行走，同时认知负荷逐渐增加（无认知负荷、专注倾听、倒拼短单词和倒拼长单词）。未给出具体的任务优先级指示。在随机步的足跟触地之前施加内侧和外侧足部放置扰动。
在无扰动和有扰动的情况下，认知表现有所下降。虽然相对于无扰动行走，有扰动时平衡控制下降，但额外的认知负荷在扰动期间对平衡控制影响不大。最后，通过踝关节和髋关节的峰值关节力矩测量的平衡恢复策略不受额外认知负荷的影响。
在经历足部放置扰动时，个体似乎会优先考虑平衡控制而非认知表现，并且不会因增加认知负荷而改变其平衡恢复策略。这些结果突出了年轻人任务优先级分配的灵活性，并为未来分析神经功能受损人群的研究奠定了基础。
