RecruitingBehavioural interventionUp-2 Study: Cognitively Engaging Walking Exercise and Neuromodulation to Enhance Brain Function in Older AdultsDeclines in cognitive function and walking function are highly intertwined in older adults. A therapeutic approach that combines complex (cognitively engaging) aerobic walking exercise with non-invasive electrical brain stimulation may be effective at restoring lost function. This study tests whether electrical stimulation of prefrontal brain regions is more beneficial than sham stimulation.