Cognitive dual-task alters Local Dynamic Stability of lower extremity during common movements

A dual-task paradigm is most commonly used in the field of biomechanics to understand the effect of multi-tasking or cognitive load on motor performance. The Local Dynamic Stability (LDS) is most commonly used to quantify motor performance, but there are still several unknown effects of this metric with varied task conditions and cognitive demands. Therefore, this study used motion capture to collect biomechanical data from 28 healthy collegiate participants during a walk and jog task both with and without a semantic fluency task to investigate the effects of task speed, limb dominance, and semantic fluency on LDS. This study showed that the change in ankle plantarflexion LDS during a jog was dependent on self-selected speed. Participants with slower jogging speeds increased ankle plantarflexion LDS during a dual-task, while individuals with faster jogging speeds decreased ankle plantarflexion LDS during a dual-task. This study also found that subjects compensate during gait by both increasing and decreasing LDS in different degrees of freedom of the lower extremity. This study did not find evidence of limb dominance effecting the change in LDS during a dual-task while walking or jogging. These findings reveal where healthy adults compensate for simple movement patterns while multitasking. Future work should further explore the role and relationship between trunk movement and lower extremity compensation, and could help give further context to how the LDS can be interpreted by researchers and clinicians alike.