Effects of dual tasks on kinematic and kinetic performances during stair descent: respective effects of manual and cognitive tasks

BACKGROUND: Stair descent is one of the most common and challenging daily activities for several populations, particularly under dual-task conditions. This study investigated the effects of cognitive or manual task on kinematics and kinetics during stair descent. METHODS: A total of 37 participants performed stair descent under three conditions: stair descending only, stair descending while performing a cognitive task and stair descending while performing a manual task. Kinematic and kinetic data were collected. Multivariate analysis of variance with repeated measures was conducted to test the significant differences among the three conditions. RESULTS: The gait performance, loading rate, lower limb joint moments and powers were significantly lower under the two dual-task conditions compared with stair descending only. The participants had lower knee flexion/extension range of motion, loading rate, peak hip flexion moment, first peak knee extensor moment, second peak ankle plantar flexion moment, first knee power absorption and less stride width under the manual task compared with the cognitive task. CONCLUSIONS: Dual tasks during stair descent had a significant impact on the kinematics and kinetics of motion, and the effect was more significant while performing a concurrent manual task in healthy young adults. Further studies could focus on the complexity level of dual tasks on the biomechanical parameters during stair walking.