Effects of Task Difficulty on Postural Control During a Combined Gait Termination and Manual Task

Task difficulty is a major factor that affects postural control and stability. However, there is little information about the effects of task difficulty on postural control during gait termination in combination with a manual task. The present study investigated postural control during combined gait termination and a manual task with different levels of manual task difficulty. Right-handed, healthy young adults (n = 15) performed five trials of combined gait termination with a manual fitting task for each of four different manual task conditions, varying target size (large and small) and distance (short and long). Average time-to-contact of the center of pressure and upper body (sternum) was assessed in three separate phases of the combined task: preparation, reaching, and stabilization phases. Longer reaching distance reduced time-to-contact not only in the reaching phase but also in both the preparation and stabilization phases. However, there were no effects of target size on time-to-contact. These results indicate that increasing manual task demands requires integration throughout gait termination and can impact postural stabilization after task completion even in young healthy adults.