In order to examine age-related differences in ability to respond and move rapidly to a visual stimulus, a total of 13 young (mean age = 23.8) and 13 older women (mean age = 61.8) underwent seven days of testing over a 6-week period on a rapid, self-terminated elbow flexion task, with two inertial load conditions (with added load and no added load). The subjects underwent four consecutive days of testing to assess age-related differences in practice improvements and to ensure stability of criterion measures. Subjects were required to rapidly move the lower arm through 90 degrees of movement stopping at a terminal position. Performance was judged across a variety of measures, including reaction time, kinematic characteristics, and electrical activity (EMG) of the biceps brachii and triceps brachii muscles. Following the practice days, all women received a 7-10 day layoff prior to re-testing, designed to assess short-term retention of any practice improvements. Following this re-test day, subjects received an additional 30 day layoff, prior to two final tests days designed to assess long-term retention and possible relearning. Results indicated that the older women were no slower in reaction time and improved reaction time following practice to the same extent as younger women. Once movement was initiated, the older women displayed slower movements, slower velocity and acceleration in both load conditions. The older women were more accurate initially and following practice, although younger women also improved accuracy following practice. The performance decrements seen in the older women were magnified when no added load was present. No age-related forgetting was seen across retention periods, with the exception of the older group becoming less accurate following the periods of no testing. Both groups of women displayed asymmetrical acceleration profiles and other EMG characteristics that suggested they had difficulty in activating the triceps brachii muscle to stop the movement at the terminal position. It can be concluded that the younger women displayed inefficient EMG characteristics during the loaded condition, while the older women were compromised in their ability to move rapidly in both load conditions.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-9061 |
| Date | 01 January 1995 |
| Creators | Hilliard, Timothy Scott |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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