Dual-Task Interference Impairs the Acquisition of Standing Balance Skills

Cortical areas, including the primary motor cortex (M1), are engaged during motor learning; however, their role in acquiring balance skills remains uncertain. By incorporating a concurrent cognitive task that demands attentional and cortical resources, this study investigated whether early balance learning depends on cortical engagement. Twenty-five healthy young adults were divided into a control group (n = 13; four males; age: 21.38 ± 1.98 years) and a dual-task group (n = 12; three males; age: 21.91 ± 2.11 years). Both groups underwent a balance training session consisting of five sets of three 40-s trials on a balance board. The dual-task group counted backward by threes from a random number during training. Throughout the training, the tilt angle of the balance board was recorded in both the anteroposterior (AP) and mediolateral (ML) directions using an accelerometer mounted on it. Balance performance was quantified using the tilt angle, standard deviation of the tilt angle, and the tilt-angle speed. Balance improved in both groups, as shown by significant reductions in standard deviation of the tilt angle in both directions, and tilt angle and tilt speed were reduced across both groups in ML. Conversely, only the control group demonstrated significant improvement in AP tilt speed between the first and third, second and third, and first and fifth sets (t = 3.7, p = 0.003, d = 1.45; t = 2.8, p = 0.044, d = 1.11; t = 3.2, p = 0.016, d = 1.26, respectively). Furthermore, the control group showed a significantly lower tilt speed than the dual-task group in the third set (t = 2.1, p = 0.044, d = 0.92). In conclusion, the present findings suggest that performing cognitive tasks concurrently with balance training may disrupt the acquisition of balance skills. This disruption cannot be attributed solely to increased cognitive demands but also to heightened attentional demands, which cause competition for shared cortical resources and potential interference with balance learning. These findings highlight the role of cortical structures in early balance learning and could inform future studies aimed at optimizing rehabilitation training protocols.