RESUMO
BACKGROUND: Previous dual task studies suggested that the difficulty of the concurrent cognitive and motor tasks may not be challenging to the same degree for each person. This study approaches this problem by setting individualized difficulty levels for tasks to examine the dual task interference. RESEARCH QUESTION: Do the features of postural sway depend on increased individualized difficulty levels of concurrent cognitive and postural activities? METHODS: 20 young healthy participants (10 male, 10 female) took part in the study. Before the experiments, cognitive task difficulty (No-, Medium-, High) has been set individually. Subjects performed postural tasks (quiet stance, voluntary sway) concurrently with or without a cognitive task which based on simple arithmetic calculations. Postural sway features were examined. RESULTS: Postural sway features were affected by individualized difficulty level of concurrent cognitive and postural activities. In voluntary sway, as a more challenging postural task, higher reductions were observed for such sway features as COP velocity and range in AP direction. SIGNIFICANCE: This study signaled task-specific changes in postural sway features. When the difficulty levels were set individually, the effect of motor and cognitive dual task was more apparent when the balance requirement of the primary motor task increased.