Motor Performance

Kinematic profiles may be examined to provide additional analyses of possible sources of slower movements. The movement optimization model (Meyer) divides the velocity and acceleration profiles into primary and secondary submovements. The primary submovement represents the ballistic, or prepared, portion of movement, whereas the secondary submovement represents the feedback, or corrective, portion of movement control (see Figure 2C; 2F). Adjustments to the microstructure of the movement indicate how movement control changes with task constraints. The primary submovement is shortened in older adults, requiring them to make more secondary, corrective submovements to reach a target (see Figure 2F). Older adults are Figure 2 Kinematic and Submovement Parsing: Young and older adult position, velocity, and acceleration profiles. For a complete caption, please see the section "Figure Legend" at the end of this essay. known to decrease the distance traveled in the primary submovement and increase the number of corrective submovements in a variety of tasks. The shortening of the primary submovement may be a consequence of bodily changes and/or decrements in processing capacity and efficiency. Specific causes may include the inability to prepare and organize movement effectively, reduced proprioception, abnormal muscle activation patterns, increased reliance on vision, and the inability to produce or scale forces efficiently.