Relative Cognitive–Motor Interference During Dual-Task Walking: Effects of Sex, Task Type, and Difficulty

Sex-related differences in task prioritization during dual-task (DT) walking have been reported in older adults; however, whether similar patterns exist in healthy young adults remains unclear. This study examined the effects of sex, task type, and difficulty on task prioritization in DT walking. Twenty-eight young adults (14 females, 14 males) completed 30-s walking trials under single-task and four DT conditions. Dual-task effects (DTE) were calculated for motor and cognitive performance, and relative cognitive–motor interference was quantified using the Task Prioritization Score (TPS). Positive TPS values were observed across DT conditions, indicating proportionally greater motor than cognitive interference, with no significant sex differences. Motor performance declined significantly across conditions, irrespective of task type or difficulty (p < 0.001). A significant cognitive task type-difficulty × sex interaction was observed for DT cognitive performance (p = 0.038). Participants who completed DT trials first exhibited greater motor DTE, indicating a task-order effect. Exploratory analysis revealed a negative association between serial subtraction-by-3 performance and TPS (r = −0.409, p = 0.031). These findings suggest that relative cognitive–motor interference is independent of sex, although cognitive performance during DT may exhibit task-specific sex differences, and task order is an important methodological consideration in DT research.