Treadmill desks have been used extensively to increase physical activity and decrease sedentary time in the work environment. However, dual tasking, such as simultaneously walking and performing a cognitive task, may result in diminished performance in one or both tasks.
Do age and sex impact ability to dual task while using a treadmill desk at a preferred walking speed?.
A total of n = 24 younger (range of 18-24 years, mean age = 21.1 ± 1.6 years) and n = 25 older (range of 45-65 years, mean age = 53.0 ± 5.1 years) adults self-selected a comfortable walking speed ranging from 0.5 to 2.0 mph and performed the Stroop Color & Word test (measuring Inhibition) and the Sternberg Test of Working Memory (measuring Working Memory) while walking at their chosen speed on a treadmill desk and while seated. Testing was performed in two separate sessions with the order counterbalanced. Step length, stride length, gait cycle time, and coefficient of variation (CV) for each were measured using OptoGait software, and both reaction time and accuracy for the two cognitive tests were assessed. Dual Task Cost (DTC) was calculated by using the formula (Single task score – Dual task score)/Single task score)*100.
Younger adults had faster reaction time compared to older adults for both Working Memory and Inhibition tests (p < 0.05), and both males and females had slower reaction time for the Working Memory test when seated compared to walking (p < 0.05). For DTC, older adults had greater stride length CV during the Working Memory task (32.0 % vs 19.6 %), and regardless of age or sex, DTC for gait was greater than for cognition.
These data provide evidence that while aging does decrease reaction time while dual tasking, few age differences and no sex differences were found in dual task cost. However, dual tasking results in diminished gait DTC compared to cognition DTC regardless of age or sex.

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