The health benefits of physical activity are widespread across the human body – including the brain. Particularly in older adults, physical activity has been shown to promote cognitive function, protect brain structure against expected age-related declines, and potentially even reduce the risk, or delay the onset, of dementia. Using in vivo neuroimaging methods, the last decade has seen significant developments in our understanding of the mechanisms behind these effects. Using proton Magnetic Resonance Spectroscopy (1H-MRS), metabolites which are more commonly found in glia than in neurons, such as myo-inositol (mIns), total creatine (tCr) and total choline (tCho), have been shown to be increased in older adults. Overactive glial cells – as observed in some brain diseases – can result in chronic neuroinflammation. Importantly, the same metabolites have been reported to negatively correlate with performance on a working memory task, suggesting a potential mechanistic link between age-related changes in brain metabolites and cognitive function. The current study will test whether exercise modulates these markers of neuroinflammation in older adults and, crucially, if these changes explain exercise-induced cognitive improvements. To examine the effects of a single exercise session on brain metabolite concentrations and working memory function, forty-eight older adults (65 – 75 years old; 50% women) will undergo a working memory test and 1H-MRS imaging at 7 Tesla before and after a cycling exercise. Exercise protocols are individualized to each participant, based on their performance on a VO2 max fitness test. In addition, participants will attend a control session, where they will undergo the same working memory test and brain scans before and after remaining seated. Data collection is currently underway. If exercise-induced metabolite changes are associated with cognitive changes, then these findings will contribute to our understanding of the underlying neural mechanisms of exercise-induced brain benefits in ageing.