## 1 Introduction  
Dual-task (DT) refers to the concurrent execution of two distinct activities that can be carried out independently, assessed individually, and have separate objectives [1]. This involves performing multiple tasks at the same time, such as walking while simultaneously engaging in a verbal and/or motor task. The successful performance of two simultaneous activities may be considered difficult; in fact, a previous study has reported that people have limited cognitive capacity (attentional capacity theory) [2]. Moreover, a recent study confirmed that in a healthy young population the execution of two simultaneous tasks, requiring the same cognitive resources, leads to a decrease in efficiency in one or both (dual task effect), causing cognitive fatigue with the increasing complexity of one or both tasks [3]. This interference phenomenon is especially emphasized when simultaneous activities are performed by elderly. Impaired physical activity and cognitive dysfunction due to aging are common, which results in decreased performance in one or both tasks when performed together [4]. Also, the exponential increase in the geriatric population in combination with negative changes due to morphological and pathological disorders are factors contributing to the increasing frequency of falls [5]. Identifying the risk factors which lead to falls and designing appropriate preventative interventions has become of utmost importance. The performance of a DT activity may impair both dynamic balance and cognitive function in the elderly, which leads to this increase in falls [6; 7]. Most studies examining older people's performance in DT activities include one motor task and one cognitive task [8; 9]. Executive functions in the elderly comprising working memory, inhibitory control, and cognitive flexibility are considered essential for the proper response to and resolution of everyday life problems [10; 11]. Choosing the appropriate cognitive activity during DT assessment can provide important information about older people's mobility and significantly increase the sensitivity of assessment tests to predict falls. Cognitive tasks that require more complex processing such as the calculation of mental arithmetic operations (working memory) and verbal fluency have been demonstrated to interfere with motor behaviors to a greater extent than tasks that involve automatic central processing, such as reaction time [12]. Nonetheless, geriatric research has not extensively examined how task dependency influences DT gait [13]. The motor tasks typically used involve either the 6- to 10-m gait tests or the TUG test [14]. Tests that involve leaning from a chair, walking, and turning, such as the Timed Up and Go (TUG) test, appear to provide important information compared to the walking tests [14]. Although gait tests can highlight to a greater extent the motor performance of older people, it is often not feasible to evaluate them in a clinical setting due to the lack of necessary space and equipment. In the realm of DT gait, studies typically examine walking forward [14]. Even though turning is a common transition movement during walking, it has not received much attention despite its importance in daily life. Turning is particularly interesting because, even in settings where there is just one task involved, this fleeting motor activity is strongly associated with instability. The distinct physiological and cognitive demands of turns (in contrast to straight-ahead walking) may be the cause of this instability. One such requirement is the cognitive processing of speed [15]. In fact, turning is believed to be more than a reflexive movement; it requires cognitive processing. This involves synthesizing information from the vestibular, somatosensory, and visual systems in order to give feedback and appropriately regulate the body while in motion [16].