Influences of different cognitive loads on central common neural drives to the ankle muscles during dual-task walking.

While dual-task walking with additional cognitive tasks may decrease walking performance, many studies have also shown increases in walking performance during dual tasks, especially as cognitive load increases. However, the neural mechanisms that cause changes in postural control during dual tasks according to the difference in cognitive load remain unclear. Therefore, this study aimed to investigate the influence of different cognitive loads on the neural control of muscle activity during dual-task walking using intra- and intermuscular coherence analyses. Eighteen healthy young adults were subjected to treadmill walking measurements in a single-task condition (normal walking without cognitive load) and two dual-task conditions (watching digits and digit 2-back task) with the measurements of reaction time to auditory stimulation. During walking with the digit 2-back task, stride-time variability was significantly reduced compared to that during normal walking, and reaction time was significantly delayed compared to those during normal walking and walking with watching digits. The peak value of the tibialis anterior intramuscular coherence in the beta band (15-35 Hz) significantly increased during walking with the digit 2-back task than that during walking with watching digits. The present results suggest that young adults can increase their central common neural drive and decrease their walking variability for concentration on cognitive tasks during dual-task walking.