There is now an established body of knowledge showing that both resistance and cardiovascular exercise can benefit our thinking skills by improving the functional capacity of the brain.
More specifically, a study conducted in Australia has found the stronger people get the less likely they are to develop dementia; increased muscle strength leads to improved brain function in adults with Mild Cognitive Impairment (MCI; this is a condition placing people at greater risk of subsequently developing dementia). Findings from the Study of Mental and Resistance Training (SMART) trial have shown a positive causal link between muscle adaptations to progressive resistance training and the functioning of the brain among those aged over 55 with MCI.
These research findings add to a body of knowledge indicating that aerobic exercise can also benefit our thinking skills. For example, a study that we published in 2008 has now become a 'citation classic' (with well over 1,000 citations on Google Scholar). This research showed that, in adults with subjective memory impairment, a 6-month program of physical activity produced improvement in cognitive functioning over an 18-month follow-up period.
Taken together, these findings indicate in order to age optimally as well as participating in mentally stimulating activities and maintaining a healthy diet people need to remain physically active, including with respect to both cardiovascular and resistance exercise (if possible).