Methods
All participants performed the Timed Up and Go (TUG) test in three different conditions twice: performing TUG first at preferred movement speed (preferred condition), then while executing an additional cognitive task (counting backwards in steps of two starting from 100 in the first and from 50 in the second trial [We also implemented a fast repetitive goal-directed arm-movement test to assess upper-limb movement in sitting position. Participants were instructed to touch two platforms alternating by one hand as fast as possible within a period of 20 s (arm-movement test) while sitting on a chair. The two platforms’ base is positioned on the floor in alignment with the participant’s feet position (Fig. 
Repetitive goal-directed arm-movement