Supplementary Material

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Background: Dual tasking is a performance when people execute two tasks simultaneously. Both motor and cognitive task during walking are required in daily living. Prefrailty is a common physical de-condition in elder people. This study investigated the gait performance and brain activities during dual task in prefrail elderly.

Methods: This crossed-sectional study included 27 prefrail subjects to perform single walking (SW), cognitive dual task walking (WCT), and motor dual task walking (WMT). The gait parameters of interest included speed, cadence, stride time, stride length, swing cycle, spatial variability, temporal variability, and dual task cost (DTC). Brain activities in prefrontal cortex (PFC), premotor cortex (PMC), and supplementary motor areas (SMAs) were measured by functional near-infrared spectroscopy (fNIRS) during each walking condition. One-way ANOVA with repeated measures with post-hoc test was used for statistical analysis.

Results: The results showed significant decrease in speed, cadence, stride length and swing cycle, and increase in stride time and spatial variability during WCT compared with SW condition. There was also significant decrease in speed, stride length and swing cycle, and increase in stride time during WMT compared with SW condition. The DTC during WCT was more than during WMT. The brain activities did not change significantly during WCT or WMT as compared with SW.

Conclusion: Dual task exerted difficult in prefrail elderly during walking and WCT is even more difficult than WMT. The insignificant change in brain activities during dual task walking may result in negative impact of secondary task on gait in prefrail elderly.