Effects of aging on force coordination in bimanual task performance.

We investigated within- and between-hands grip-load force coordination in both healthy young and older adult participants during bimanual tasks involving realistic actions. Age-related changes in manual behaviors such as grip force production and safety margins were expected in older adults. Within-hand grip-load coordination was expected to decrease with aging during the performance of dynamic actions, but not static actions. The effects of task and hand dominance on task performance were also evaluated. Grip force production increased with age; however, changes in fingertip frictional properties with aging increased the risk of object slip. Indices of within-hand grip-load coordination did not alter with age, but such indices were affected by task goals. The action of connecting two independent objects, particularly with rotational action, was associated with declines in all indices of within- and between-hands force coordination, independent of age. Evidence of task-specific differences in within-hand grip-load coordination in the current data set suggests that individual hand specification emerges and persists with age in everyday bimanual prehension tasks, independent of the action role assigned to the dominant and non-dominant hands.