Effect of Intervention of Cognitive Tasks during Stair Negotiation on Lower Extremity Inter-joint Coordination

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 interjoint 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 cognitive task(dual task;DT).Result:For EA and YA,the numbers of correct cognitive test answers 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 coordination 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 coordination.