Figure 2.

Associations between trajectory or end-point variability with force (top row) or movement (bottom row) error during goal-directed tasks. Trajectory variability refers to the fluctuations in position within a trial when the task frequency is filtered out (detrended). End-point variability refers to the variations (SD) in end point (force or time) across trials. The top row demonstrates that the amplified force error observed in older adults is strongly associated with greater trajectory (left) and end point (right) variability in force (data adapted from (11)). The bottom row demonstrates similar findings for movement (data adapted from (10)). Specifically, the amplified movement error observed in older adults is strongly associated with greater trajectory (left) and end-point (right) variability in movement. Overall, these results provide experimental evidence that amplified motor output variability in older adults impairs their end-point accuracy.