上、下楼梯时认知任务介入对下肢协调性影响的研究

摘要

目的：探讨上、下楼梯时附加认知任务，年龄差异（组间）及任务难度（组内）对步态时空及下肢关节协调参数的影响。方法：18位健康老年人为老年组，18位健康大学生为年轻组，各组内均为9男9女，依次接受认知任务测试、上、下楼测试（单任务）及上、下楼合并认知任务测试（双任务）。结果：认知任务方面，两种任务情境下各年龄组上楼回答次数皆显著多于下楼。步态参数方面，两种任务情境下年轻组相对于老年组，以及各年龄组在单任务情境下相对于双任务，皆呈现较短步行时间、较快步行频率、速度及较大步行长度的情形。下肢协调性方面，年轻组上楼过渡时摆动期的膝‐踝协调稳定度在双任务下较单任务差，而处于双任务情境下，年轻组上楼过程中支撑期的膝‐踝协调稳定度比老年组差；年轻组下楼过程中摆动期的髋‐膝协调稳定度在ST 和DT 中都比老年组差，老年组膝‐踝协调稳定度比年轻组差，下楼过渡时，年轻组支撑期髋‐膝协调稳定度在两种任务情境下皆比老年组差。结论：老年人和年轻人会根据任务难度来选择是否专注于认知任务上，此外年轻人因有足够下肢肌力控制而采取较大胆动作策略，导致其上下楼梯时下肢协调稳定度较差，而老年人则趋向选择较保守的策略来维持下肢关节协调稳定度。%Objective :The aim of this study was to investigate the effect of aging and different conditions on cognitive performance ,spatiotemporal gait parameters and lower extremity inter‐joint coordination during stair negotiation .Method :18 healthy elderly adults (EA ) and 18 healthy young adults (YA ) were recruited in this study to perform a cognitive task on sitting posture .They also perform stair negotiation (single task ;ST ) and stair negotiation with cogni‐tive task (dual task ;DT ) .Result :For EA and YA ,the numbers of correct cognitive test an‐swers during stair ascent were significantly more than stair descent .Between age groups ,YA performed shorter time of the 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 the gait cycle ,faster cadence ,faster gait velocity and larger stride length than during DT .During the transition phase of stair ascent ,YA produced less stable knee‐ankle coordina‐tion in DT of swing phase than ST ,while EA did not .During stair ascent phase ,YA produced less stable knee‐ankle coordination in DT of stance phase than EA .During stair descent 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 was found in EA than YA .During ST and DT of the transition phase of stair descent ,less stable hip‐knee coordination of stance phase was detected in YA than EA .Conclusion :EA and YA alike depended on the degree of difficulty of the 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 co‐ordination .