BACKGROUND: Few studies have explored motor imagery (MI) as a way of accessing the higher-level of control of complex body movements involved in gait or balance. The objective of this study was 1) to measure and compare the time needed to complete the Timed Up & Go test (TUG), the time needed to imagine performing the same test (iTUG) and to calculate the time difference between both of these conditions (delta time) in a sample of young and older adults, and 2) to examine whether there was an association between the Timed Up & Go test results (TUG, iTUG, delta time), age and cognitive decline. METHODS: A total of 162 subjects (38 healthy young adults, mean age 25.7+/-2.3 years, 73.7% women and 124 older inpatients, mean age 85.3+/-6.5 years, 76.6% women) were included in this cross-sectional study. The mean+/-SD of TUG, iTUG and delta time, age and the Mini Mental State Examination (MMSE) score were used as main outcomes. RESULTS: Age was associated with an increase in time of TUG (P<0.001) and of delta time (P=0.015), and with a decrease in time of iTUG (P<0.001), whereas cognitive decline was only associated with increase in delta time (P=0.030). There was an increase in time of TUG (P<0.001) and in delta time (P<0.001) for subjects who used a walking aid. The increase in delta time depended on the MMSE score when the subjects did not use a walking aid (P for trend=0.001). CONCLUSIONS: iTUG is clinically feasible among frail older adults and may quickly inform any clinician about higher-level changes in control of gait and balance in older adults.