STUDY PROTOCOL

Full list of author information is available at the end of the articleBackground Cognitive impairment and dementia is a pressing health care issue in older people (as described previously [1]). However, physical activity is thought to be beneficial in altering the trajectory of cognitive decline in older adults [2-4]. Although there is still considerable uncertainty concerning the appropriate type, intensity and duration of physical activity, there is evidence that regular low- to medium-level exercise leads to a 35 % risk reduction in cognitive decline in people aged 65 and above compared to inactive older people [5]. The potential mechanisms behind the protective effects of physical activity on cognitive function are thought to be multidimensional. It has been suggested that aerobic exer-cise renders the brain more efficient, plastic, and adaptive, which leads to improved memory and executive functio