A six-month pilot study involving 101 healthy older adults (65+), who were randomly put into one of three exercise interventions or a no-change control, has found that the exercise groups all showed significant improvement in visual-spatial processing and attention, with more improvement in visual-spatial processing occurring in those with higher levels of exercise.
The benefits of increasing exercise for visual-spatial processing, however, were fully accounted for by improvements in cardiorespiratory fitness, suggesting that exercise intensity may be more important than exercise duration.
The researchers suggest that individualized exercise programs designed to maximize cardiorespiratory fitness will be of greatest benefit.
The three exercise levels were: 150 minutes per week (the recommended level); 75 minutes per week; 225 minutes per week. Exercise was supervised, and mainly consisted of treadmill walking of moderate intensity. Participants exercised 3-5 days a week. Performance in five cognitive domains were tested: Verbal Memory, Visuospatial Processing, Simple Attention, Set Maintenance and Shifting, and Reasoning.
Note that only 77 individuals made it through the trial, and also adhered to at least 80% of the alloted amount of exercise. Unsurprisingly, the 225-minute group had the most trouble meeting the allotment: 70% of the group managed it, compared to 82% of the 75-minute group, and 85% of the 150-minute group. It's worth noting that, of those who met the 80% requirement, almost all (>95%) fully adhered to the prescription, and this was true across all exercise prescriptions.
Vidoni ED, Johnson DK, Morris JK, Van Sciver A, Greer CS, Billinger SA, et al. (2015) Dose-Response of Aerobic Exercise on Cognition: A Community-Based, Pilot Randomized Controlled Trial. PLoS ONE 10(7): e0131647. doi:10.1371/journal.pone.0131647