The Effect of Various Dual-Task Activities and Task Prioritization on Gait Kinematics

Gait is not an automatic task, as it requires both attention and executive function. Because attention is a limited capacity, when individuals complete more than one task at the same time, or dual-task (DT), they are required to divide attentional resources between the tasks. Dual-task walking has been found to have detrimental effects on elderly, individuals with concussions, and patients with neurological pathologies, including marked decrements in walking speed and stability. However, the various technological distractions available in today’s society have also made it necessary to investigate the effect of cell phone-based DTs on the healthy, young population. Though some research has investigated these DTs, few studies have focused on quantifying the DT interference effect on gait itself or investigated the effect of tasks other than texting. Additionally, it is currently unknown whether the healthy, young population preferentially prioritizes walking or the completion of the secondary task while DT walking, making the determination of this population’s natural prioritization strategy necessary as well. Therefore, two studies were developed in order to quantify the effect of various cell phone-based DTs on gait kinematics and to determine the natural prioritization tendencies of the healthy, young population. Fourteen college-aged individuals (7 male, 7 female; 19.64±1.39years; 171.18±8.34cm; 68.58±10.23kg) participated in both studies. The subjects were outfitted with 29 reflective markers and their motion was recorded using a motion capture system. For Study 1, each subject performed a ST walking condition and four DT walking conditions: Walk + Converse, Walk + Read (Simple), Walk + Read (Difficult), and Walk + Text. For Study 2, each subject completed texting while walking tasks under three different prioritization conditions: No Priority, Texting Priority, and Walking Priority. Peak lower extremity joint angles in the sagittal plane, gait velocity, and stride length were determined from marker position data to quantify walking performance in both studies. Texting accuracy and speed were used to quantify texting performance in Study 2. The results of Study 1 indicated that while more cognitively complex secondary tasks impacted normal gait kinematics to a greater extent than less complicated cognitive tasks, DT walking resulted in significant changes to lower extremity peak angles in the sagittal plane that contributed to a shorter stride length and slower gait velocity regardless of the difficulty of the secondary task. These findings support the classification of DT walking as a safety hazard. However, the results of Study 2 suggest that the gait characteristics of the No Priority condition were more similar to those in the Walking Priority condition than the Texting Priority condition, which could suggest that individuals preferentially focus on walking over texting in order to compensate for detrimental effects of divided attention and increase the likelihood of safe navigation through the environment