Effects Of Cognitive Or Manual Dual-tasks On Dynamic Gait Stability During Stair Descent

Stair negotiation is an activity of daily life with the potential for falls. Falls on stairs account for 26% of all self-reported falls and are one of the leading causes of accidental death. The effects of a concurrent cognitive or manual dual-task paradigm on dynamic gait stability (DGS) during stair descent remain uncertain. PURPOSE: To investigate the effects of concurrent cognitive or manual dual-tasks on dynamic gait stability. METHODS: Sixteen healthy young women participated this study (age: 21.6 ± 2.1 years; height: 162.4 ± 4.7 cm; body mass: 53.4 ± 6.7 kg) and descended a staircase under three different walking conditions: descend stairs only (single task, ST), descend stairs while subtracting serial threes from a three-digit number (cognitive dual-task, CT), and descend stairs while carrying a glass of water (manual dual-task, MT). An eight-camera motion capture system synchronized with a force plate was used to collect kinematic data and ground reaction forces at 100 Hz and 1000 Hz, respectively. Gait velocity, along with center of mass (COM)-center of pressure (COP) inclination angle (IA) in anterior/posterior (ap) and medial/lateral (ml) directions were used to represent DGS. One-way ANOVA with repeated measures was employed to compare the IAs of the three conditions. RESULTS: Peak velocities under CT (p = 0.003) and MT dual-task conditions were significantly lower (p < 0.001) than that under ST condition (CT: 0.79 ± 0.09 m/s; MT: 0.68 ± 0.08 m/s; ST: 0.91 ± 0.11 m/s). The peak of the IAA/P under the CT and MT conditions was lower (p < 0.02) than under the ST condition (CT: 8.29 ± 0.82°; MT: 7.16 ± 0.89°; ST: 9.05 ± 0.79°), and the peak of the IAA/P under MT was lower (p < 0.001) than under CT condition. The peak of the IAM/L under MT was lower (p = 0.02) than that under ST condition (MT: 5.95 ± 1.02°; ST: 6.49 ± 0.53°).: CONCLUSIONS: Compared to single-task, healthy young women have worse DGS and lower gait velocity under cognitive and manual dual-task conditions.