- 學位論文
執行雙任務時視覺變化對平衡表現之影響:探討不同年齡層之間的差異
Effect of visual changes on balance performance during dual-tasking stance in different age groups
摘要
背景與目的:隨著年齡的增長，中老年人會有平衡能力衰退之情形，在感覺功能部分可能在視覺移除或再插入時有感覺整合問題、認知功能部分可能在雙任務表現變差、動作功能方面可能在平衡受挑戰時更多採取增加肌肉僵硬度的策略。本研究欲探討不同年齡層執行平衡雙任務時視覺變化對平衡表現之影響。 方法:本橫斷式探索型研究便利取樣15位年輕人、10位中年人與14位健康老年人，採雙腳併攏站姿，每次40秒的測試中第17至22秒透過快門眼鏡使視覺訊息不預期地移除或再插入，隨機狀況進行的雙任務測試需要同時執行靜態站立平衡任務及連續減數任務，40秒內連續減1(初階)或減3(高階)。測量變項為減數雙任務虧損(因執行雙任務而導致減數表現變差的百分比)、腓腸肌僵硬度在視覺變化前後之差異(在視覺變化後之增加量)，以及足底壓力中心晃動之功率譜密度。 結果: 年齡越大，減數任務之雙任務虧損值越大，兩者呈現中度正相關。老年人的平衡表現跟年輕人與中年人相比，有著因視覺變化較大起伏的足底壓力中心變化。此外，面對視覺移除時，年輕組執行初階減數時腓腸肌僵硬度增加量顯著大於執行高階減數時，中年組沒有差異，老年組則是執行高階減數時腓腸肌僵硬度增加量大於執行初階減數時；面對視覺再插入時，三組的腓腸肌僵硬度皆沒有顯著變化。 結論:健康年輕人能有效增加小腿肌肉僵硬度來維持視覺變化後的站立平衡。在視覺變化下執行靜態站立平衡同時合併高階減數雙任務時，站立平衡的注意力需求會隨著年紀增加而增加；此時，健康中年人平衡表現雖然與健康年輕人沒有差異，會傾向使用小腿肌肉僵硬策略來維持平衡，而健康老年人即使採用僵硬策略能後成功維持平衡，平衡表現仍較年輕人和中年人差。 臨床意義:在面對較困難的平衡任務時，例如同時有感覺和認知功能的挑戰，不同年齡層之健康人會依據感覺情境與個體注意力資源需求，來採取不同的平衡控制策略，雖然中年人的平衡表現與年輕人沒有差異，但是仍可能會傾向使用僵硬策略來維持平衡，因此中年人與老年人應開始進行感覺整合與再整合的雙任務平衡訓練，來防範未來跌倒風險。
並列摘要
Background and purpose: With age, middle-aged and elderly people may experience decline of balance ability. The sensory function may have sensory organization problems during visual removal or reinsertion. The cognitive function may worsen in dual task performance, and the motor function may need more stiffening strategies to increase muscle stiffness when balance is challenged. The aim of this study was to investigate the effect of visual changes on balance performance in individuals of different ages when maintaining dual-task balance. Methods: This cross-sectional exploratory study enrolled a convenient sample of 15 young adults, 10 middle-aged adults, and 14 healthy elderly adults in standing position with feet together. Visual information was unexpectedly removed or reinserted through electronically controlled shutter goggles during 17th to 22nd seconds of each 40-second trail. The dual-task was performed in random order, which required simultaneous execution of static standing balance task and continuous subtraction task, i.e., continuously subtract 1 (entry level) or 3 (advanced level). Measured outcomes were dual-task cost of subtraction performance, difference in gastrocnemius stiffness before and after visual change, and power spectral density of sway of center of pressure. Results: The dual-task cost of subtraction performance increased with age; a moderate positive association was found. The balance performance of elderly adults showed larger changes of postural sway after visual change, comparing to the young and middle-aged adults. In addition, with visual removal, the young adults had significantly greater increase of gastrocnemius stiffness in the entry-level than in the advanced-level subtraction. No difference was found in the middle-aged adults, whereas the elderly adults had significantly greater increase of gastrocnemius stiffness in the advanced-level than in the entry -level subtraction. With visual reinsertion, there was no immediate significant change of gastrocnemius stiffness in the three groups. Conclusions: Healthy young adults could effectively increase the stiffness of lower leg muscle to maintain standing balance after visual changes. When maintaining standing balance combined with visual changes and advanced-level subtraction tasks, the attentional demands of standing balance increase with age. Although the balance performance is no different from that of young adults, healthy middle-aged adults tend to use stiffening strategy to maintain balance. Healthy elderly adults can successfully maintain balance with stiffening strategy, but their balance performance is worse than that of young and middle-aged adults. Clinical significance: When facing difficult balance tasks, such as simultaneous sensory and cognitive challenges, people of different ages may employ different balance control strategies according to sensory situation and individual attention demands. Although the balance performance of middle-aged adults is not different from that of young adults, it is the age that people start to use more stiffening strategy to maintain balance. Therefore, the middle-aged and elderly adults should begin to train balance ability with sensory organization, sensory reintegration, and dual-tasking, in order to prevent future falls.
參考文獻
延伸閱讀
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