Isometric pinch force control and learning in older adults.

The learning of a dynamic isometric pinch force task was investigated in young adults (aged 19 to 29 years) and older adults (aged 64 to 75 years) through use of a visuo-motor tracking paradigm. Both groups significantly improved performance over trials, retained what was learned 1 week later, successfully transferred to a new target, and demonstrated interlimb transfer of training effects, reflecting a strong central component to this task that is apparently intact in older adults. However, performance differences between the two groups remained throughout the trials. Although it appeared that older adults were able to utilize a model-based strategy to predict the target path, as evidenced by minimal response lag, their absolute performance was inferior to that of young adults relative to an overall root mean square error score, a correlation coefficient, and their increased use of high-frequency components in the tracking signal. The age-related performance differences may be attributable to a peripheral decrement in tactile sensibility and/or muscle reorganization as well as a slowness in processing afferent information.