目的：藉由功能性的上下樓梯動作，探討年齡差異（組間）及不同任務情境（組內），對認知任務表現、步態時間空間及下肢關節協調參數之影響。方法：16名老年人受試者 (7男9女, 79.16 ± 6.97 歲, 160.49 ± 7.27 公分, 62.16 ± 11.26 公斤) 及12名年輕人受試者 (6男6女, 23.00 ± 1.21 歲, 165.25 ± 4.11 公分, 60.25 ± 6.90 公斤)，皆須接受坐姿的認知任務測驗、上下樓梯行走測驗，以及上下樓梯合併認知任務回答測驗。結果：老年人上樓梯回答次數顯著多於前測及下樓梯，而後測也顯著多於前測，年輕人上樓梯和下樓梯回答次數顯著多於前測，而後測回答次數也顯著多於前測。不同年齡組別間，年輕人在兩種情境下相對於老年人，呈現較短的步行時間、較快的步行頻率、較快的步行速度及較大的步行長度，而不同情境間，年輕人和老年人在單一任務情境下相對於雙重任務，呈現較短的步行時間、較快的步行頻率、較快的步行速度及較大的步行長度。關節協調穩定性部分，上樓梯轉換期，年輕人在擺盪期的雙重任務情境下，膝-踝協調的穩定性比單一任務情境還差，但老年人卻沒有。在上樓期階段，站立期的膝-踝協調穩定性，雙重任務情境下，年輕人的穩定性比老年人還要差。下樓期階段，年輕人在擺盪期的單一和雙重任務情境下，髖-膝協調穩定性都比老年人還差，相反地，老年人的膝-踝協調穩定性則比年輕人還差。在下樓轉換期，年輕人在單一和雙重任務的情境下，站立期的髖-膝協調穩定性都比老年人還差。結論：老年人和年輕人會根據動作的困難度，選擇是否專注於認知任務上。年輕人在上下樓梯的動作中，協調穩定性較差，是因為有足夠的下肢肌力控制，採取較大膽的動作策略，老年人剛好相反，都趨向選擇較保守的策略，來維持下肢關節協調的穩定性，老年人顯然在下樓梯時，受到的影響較大，但年輕人則反之，因此，下樓梯動作可能造成老年人跌倒的風險提高。

Purpose: The aim of this study was to investigate the effect of aging (between groups) and different conditions (within group) on cognitive performance, spatiotemporal gait parameters and lower extremity inter-joint coordination during stair negotiation. Methods: 16 healthy elderly adults (EA) (7 males and 9 females, 79.16 ± 6.97 years, 160.49 ± 7.27 cm, 62.16 ± 11.26 kg) and 12 healthy young adults (YA) (6 males and 6 females, 23.00 ± 1.21 years, 165.25 ± 4.11 cm, 60.25 ± 6.90 kg) were recruited in this study to perform cognitive task on sitting posture and stair negotiation (single task; ST); they also performed stair negotiation with cognitive task (dual task; DT). Results: For EA, the numbers of correct cognitive test answers during stair ascent (SA) were significantly more than pre-test and stair descent (SD), and during post-test were also significantly more than pre-test. For YA, the numbers of correct cognitive test answers during SA and SD were significantly more than pre-test, and during post-test were also significantly more than pre-test. Between age groups, YA performed shorter time of gait cycle, faster cadence, faster gait velocity and larger stride length than EA. Within different conditions group, during ST, both YA and EA took shorter time of gait cycle, faster cadence, faster gait velocity and larger stride length than during DT. During transition phase of SA, YA produced less stable knee-ankle coordination in DT of swing phase than ST, while EA did not. During SA phase, YA produced less stable knee-ankle coordination in DT of stance phase than EA. During SD phase, YA revealed less stable hip-knee coordination in both DT and ST of swing phase than EA. On the contrary, less stable knee-ankle coordination were found in EA than YA. During ST and DT of transition phase of SD, less stable hip-knee coordination of stance phase were detected in YA than EA.
Conclusion: Elderly and young subjects alike depended on the degree of difficulty of motor task to determine whether to focus on cognitive task or not. Displaying less stable inter-joint coordination during stair negotiation in YA may result from greater lower muscle strength capacity to perform unrestricted movement strategies. Contrarily, EA had tendency to adopt more conservative strategies so as to maintain stability of lower extremity inter-joint coordination. Apparently, EA got a bigger influence on SD, but YA did not do so. Therefore, the increasing of falling risk in EA may be caused by SD movement.

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