背景和自的:姿勢一上姿勢作業(postllral-sllprapostural task) 指的是在維持姿勢平衡下同時進行另一項活動， 而土姿勢作業的力量控制為影響雙重作業整體表現的重要因素。然而， 力量控制與姿勢控制間相互關你的影響 尚未被仔細探討，本研究目的為探討不同上姿勢作業力量控制對姿勢平衡的影響。方法:本研究招募12 位健 康年輕受試者，受試者需站立於平衡板(stabi lometer) 上，執行一項單一姿勢作業與三項姿勢一上姿勢雙重作 業。姿勢作業為維持平衡板於最大前傾角度之50% ;上姿勢作業為右手大拇指與食指精準按壓動作，且需分別 控制按壓力量於25% 、50% 、75% 之最大精準按壓力量。分析參數包含精準按壓力量誤差、平衡板角度誤差、 按壓尖峰力量變異係數(coefficient of variation) 及平衡板角度改變之近似摘(approximate entropy) 。結果: 相較 於50% 與75% 目標力量， 25% 目標力量會產生較大的精準按壓誤差與變異係數(p < 0.001) ;但平衡板角度誤 差與近似爛數值皆不受上姿勢作業有無與目標力量影響。結論: 健康年輕人站立於不穩定平面且同時執行快速 手指精準按壓動作峙，於目標力量較低的情況下，力量控制較差。此外，額外進行上姿勢作業或改變上姿勢作 業的力量需求並不一定會造成姿勢表現的改變，代表當注意力資源足夠處理雙重作業或作業難度較低峙，於姿 勢. 上姿勢情境下仍可維持良好的姿勢控制。關於力量控制對姿勢平衡的影響，未來可延伸此研究於老人或神 經疾患患者，探討更深入的姿勢一上姿勢雙重作業控制。(物理治療2016;4 1 (3):223-229)

Background and purpose; Postural-suprapostural task is defined as postural control takes place while completing another concurrent task, and force control of suprapostural task is considered as a critical factor for dual task execution. However, the interaction between force control of a suprapostural task and postural control is rarely understood, llie purpose of this study was to investigate the differences in performance by adopting force-in tensity for suprapostural task. Methods: Twelve young healthy adults were recruited in this study. Each subject was required to perform a single postural task (stabilometer stance) and three postural-suprapostural tasks while keeping balance on a stabilometer and performing a suprapostural task concurrently. The suprapostural task was a precision grip force-matching task with a target force of 25%, 50% or 75% of MVC. The force-matching erroi postural error, CV (coefficient of variance) of peak precision grip force and postural ApEn (approximate entropy) were measured. Results： Compared to 50% and 75% MVC condition, grcatevSt force-matching error and CV of peak force were found in rhe 25% MVC condition (p < 0.001), And postural error and ApEn were not difFerent between the single-posture and postmal-supmpostural task, and also did not be afFected by force-intensity of suprapostural task. Conclusion: With a lower force-level demand, young healthy adults could not control the force output precisely. And postural cojitrol was not necessarily afFected by an additional motor task or different suprapostural tasks. The influence of force control on postural-suprapostural task could be investigaced for elderly or patients with neurologic disorder in furure studies, (FJPT 2016；4l(3)：223-229)