The interacting effects of breaking up prolonged sitting with a single bout of exercise, plus regular short intervals of exercise, on blood flow to the brain and cognitive function in overweight adults

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In recent years the, role of physical activity in healthy brain ageing has also been a major topic of investigation. Observational studies have shown that adults who are physically active are more likely to have better performance on several cognitive test tasks, including those involving higher order executive functions. Regular physical activity during midlife has also been associated with a significantly slower rate of cognitive decline and reduced risk of developing dementia in later adulthood. Such evidence has prompted calls to investigate the potential role of regular exercise as a protective factor against cognitive decline and dementia. Traditionally, the physical activity public health focus has been directed at purposeful exercise for health benefits, at a moderate to vigorous-intensity. Emerging evidence suggests that targeting the adoption of moderate to vigorous exercise in the population should not be the only consideration; a focus on reducing sedentary behaviour may be equally important for health outcomes. Previous work has provided epidemiological and experimental evidence on the independent associations of sedentary behaviour with metabolic health. Together, with The University of Western Australia, we propose to undertake a randomised cross-over trial in 48 older overweight adults involving three experimental conditions. All participants will complete each of the three (one-day) experimental conditions, separated by a 7-day washout period to account residual physiological effects of the acute exercise. We will examine whether, compared to uninterrupted sitting, there are acute effects of a single bout of moderate-intensity exercise, with or without intermittent (3 min) light-intensity activity breaks from prolonged sitting, on cognitive function and metabolic function in overweight adults aged between 55 and 80 years of age. We hypothesise that (1) a continuous 30 minute bout of moderate-intensity exercise will lead to improvements in cognitive function relative to uninterrupted sitting, and (2) that the magnitude of the improvement in cognitive function resulting from the exercise bout, compared to uninterrupted sitting, will be greater when an exercise bout is combined with a series of brief intermittent light-intensity breaks from prolonged sitting. Furthermore, we aim to examine an exploratory hypothesis that the improvement in cognitive function associated with both the continuous 30 minute bout of exercise and the brief intermittent breaks from prolonged sitting will be associated with mechanisms which increase cerebral blood flow and glucose uptake.