The effects of vision on force control in young and old adults / by Michelle A. Pullen.
| Author/creator | Pullen, Michelle A. author. |
| Other author | Hortobágyi, Tibor, degree supervisor. |
| Other author | East Carolina University. Department of Exercise and Sport Science. |
| Format | Theses and dissertations |
| Production | 2005. |
| Description | viii, 67 leaves : illustrations, forms ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | Age affects not only the motor output by reducing muscle mass and muscle strength, but also by modifying the sensitivity and threshold of the sensory receptors. Elements of the sensorimotor system become impaired to a different extent with advancing age and there are suggestions in the literature that one system may compensate for reduced function in another system. We tested this possibility by comparing the variability of force during voluntary muscle contractions between young and old adults. Healthy young (age 22 ±4, n = 12) and old adults (age 77 ±6, n - 12) were instructed to perform 5 s-long voluntary eccentric (15 deg/s) quadriceps contractions at 20% and 40% of maximal force as smoothly as possible with eyes open (EO) and eyes blindfolded (EB). Old adults showed 7.23 coefficient of variation (CV) units more force variability than young adults with EO and only 3.94 CV units more force variability with EB. This shrinkage in force variability was due to young adults performing actually more poorly and old adults performing at about the same level with EO and EB. Force variability was independent of contraction intensity (20 and 40% MVC) in the two age groups. In a side-study, young (1.5 CV units) and old adults (2.5 CV units) showed a similar increase in force variability from EO to eyes closed behind blindfold (ECB) and a greater increase from EO to eyes open behind blindfold (EOB) in old (7.5 CV units) but not young (1.5 CV units) subjects, suggesting that old adults use sensory information differently than young adults. The results from the main experiment suggest that old adults performed the steadiness tasks surprisingly well, suggesting that compensations may occur between elements of the sensorimotor system to avoid reductions in motor output. One possibility is that the compensation for the absence of visual input may have come from muscle proprioceptors. |
| General note | Presented to the faculty of the Department of Exercise and Sport Science. |
| General note | Advisor: Tibor Hortobagyi |
| Dissertation note | M.A. East Carolina University 2005 |
| Bibliography note | Includes bibliographical references (leaves 49-53). |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
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