Evaluation of an inertial sensor system for analysis of timed-up-and-go under dual-task demands

Functional tests, such as the timed-up-and-go (TUG), are routinely used to screen for mobility issues and fall risk. While the TUG is easy to administer and evaluate, its single time-to-completion outcome may not discriminate between different mobility challenges. Wearable sensors provide an opportunity to collect a variety of additional variables during clinical tests. The purpose of this study was to assess a new wearable inertial sensor system (iTUG) by investigating the effects of cognitive tasks in a dual-task paradigm on spatiotemporal and kinematic variables during the TUG. No previous studies have looked at both spatiotemporal variables and kinematics during dual-task TUG tests. 20 healthy young participants (10 males) performed a total 15 TUG trials with two different cognitive tasks and a normal control condition. Total time, along with spatiotemporal gait parameters and kinematics for all TUG subtasks (sit-to-stand, walking, turn, turn-to-sit), were measured using the inertial sensors. Time-to-completion from iTUG was highly correlated with concurrent manual timing. Spatiotemporal variables during walking showed expected differences between control and cognitive dual-tasks while trunk kinematics appeared to show more sensitivity to dual-tasks than reported previously in straight line walking. Non-walking TUG subtasks showed only minor changes during dual-task conditions indicating a possible attentional shift away from the cognitive task. Stride length and some variability measures were significantly different between the two cognitive tasks suggesting an ability to discriminate between tasks. Overall, the use of the iTUG system allows the collection of both traditional and potentially more discriminatory variables with a protocol that is easily used in a clinical setting.