## 4 Discussion  
### Comparisons of Motor Performance between the DT and TUG Tests  
The study's results indicated that, among the community-dwelling elderly women, not only there was a decrease in motor performance in the DT activities compared to the simple motor activity, but also a different response to the demands of the four dual-task conditions. Initially, all four different cognitive-motor DT activities, utilizing the TUG test, were found to be more challenging for all participants. This was evident from the longer time needed to complete these tasks, compared to the TUG performed as a simple activity, verifying the first research hypothesis. Comparing motor performance between the different DT tests, it was found that the type of cognitive task modulated the magnitude of the reduction in performance on the TUG test with DT in this sample. The mental calculation test (\(\text{TUG}_{\text{MC}}\)) was performed with the longest duration among the four DT tests. This indicates that it contributed to the greater reduction in motor performance compared to the single TUG test, as evidenced by the high rates of DTCs. The DT test involving verbal fluency (\(\text{TUG}_{\text{VF}}\)) showed a smaller but similar decrease in motor performance compared to the \(\text{TUG}_{\text{MC}}\) test. This is also shown by the high relationship between the tests, where the \(\text{TUG}_{\text{MC}}\) and \(\text{TUG}_{\text{VF}}\) tests showed a similar positive correlation with the TUG test, verifying the second research hypothesis. Moreover, among the four DT tests, the DT test involving verbal reaction to an auditory stimulus (\(\text{TUG}_{\text{RE}}\)) showed the smallest change in motor performance compared to the simple TUG test, as shown by the high relationship between these two tests. That is, the \(\text{TUG}_{\text{RE}}\) test appears to have been the easiest cognitive-motor DT test for this sample, verifying the third research hypothesis. Finally, the memory recall test (\(\text{TUG}_{\text{ME}}\)) showed a smaller increase in execution time than the \(\text{TUG}_{\text{MC}}\) and \(\text{TUG}_{\text{VF}}\) tests and a larger increase in execution time than the \(\text{TUG}_{\text{RE}}\) test, thus being characterized as being of moderate difficulty. The selection of cognitive task is a key contributor to an older person's motor performance during the performance of a DT task. These results align with the findings of [PERSON] et al. 's meta-analysis [12]. The simultaneous performance of mental calculations or verbal fluency cognitive tasks in combination with a motor task disrupted motor behavior more than performing a cognitive-motor DT test involving a stimulus reaction task. Also, the same meta-analysis [12] reported that the working memory task led to a significant modulation of the DT test. Activities that induce internal interference, such as \(\text{TUG}_{\text{MC}}\) and \(\text{TUG}_{\text{VF}}\), may interfere with gait measurements more than activities that induce external interference, such as \(\text{TUG}_{\text{RE}}\). Walking leads to heightened brain activity in the primary sensorimotor and supplementary motor regions within the frontal and parietal  
Figure 1: Relationships between Timed Up and Go (TUG) test performance and (a) \(\text{TUG}_{\text{ME}}\), (b) \(\text{TUG}_{\text{MC}}\), (c) \(\text{TUG}_{\text{VF}}\) and (d) \(\text{TUG}_{\text{RE}}\) performance. lobes [28]. Except for the \(\text{TUG}_{\text{RE}}\) test, all the other cognitive tests are accompanied by brain activities that are interrelated with those that control movement. During the performance of a verbal fluency task, activation is observed in the frontal and prefrontal regions [29]. Conversely, cognitive tasks involving reaction to auditory stimuli are typically automatic and depend largely on subcortical neural networks. As a result, they tend to cause less disruption to motor behavior during DT activities [12].