The purpose of this study was to elucidate the control process for single-joint movements by examining behaviors of preprogrammed and on-line modulated muscle activation patterns that emerged in different task situations. Twelve subjects performed 35$\sp\circ$ and 70$\sp\circ$ elbow extension movements at two velocities with unstable external loads. / For each response, EMG activities of the triceps brachii and biceps brachii were acquired and digitized. The digitized EMG activities were used to calculate multiple EMG variables. Significant multivariate ANOVAs on overall dependent variables were followed by univariate ANOVAs on individual EMG variables, which suggested that only the agonist area for the first 50 ms of movement (Ago50) could be identified as a preprogrammed muscle activity. While external loads did not affect Ago50, velocity requirements and movement amplitudes had significant effects on Ago50, implying that knowledge about initial task constraints is incorporated into preprogramming of motor commands. / However, analyses on other EMG variables, including the first 50 ms of antagonist activity, agonist and antagonist areas after the first 50 ms of movement, their peak amplitudes, and times to reach the peak amplitudes, suggested that these variables could be identified as on-line modulated muscle activation patterns. Unlike the Ago50, they were sensitive to unexpectedly altered external loads, implying that the control system can utilize current sensory input in programming these muscle activation patterns. / Observed patterns of EMG variables suggest that the movement control process involves both preprogramming and on-line modulation of motor commands. Although the control system must preprogram some of the controlling factors before it can initiate a specified movement, the preprogrammed motor commands are not key determinants of the final movement outcome. Instead, the accuracy of the final movement outcome will be determined by the precision of both preprogrammed and on-line modulated controlling factors. Therefore, the control system has to operate continuously during the movement control process utilizing both its predictive ability and current sensory input as the basis for achieving a specified movement goal. / Source: Dissertation Abstracts International, Volume: 57-03, Section: B, page: 1642. / Major Professor: Tonya Toole. / Thesis (Ph.D.)--The Florida State University, 1996.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_77684 |
| Contributors | Park, Sangbum., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 176 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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