Exercise makes you smarter... but how much do you need to maximise its benefits? When it comes to physical health, the general principle according to exercise guidelines is: “Some exercise is better than none and higher doses generally convey greater benefit.” Is the same true for cognitive benefits? That’s what a recent study from the University of Kansas, published in PLoS ONE, set out to discover.
The researchers divided 101 volunteers, all over 65 and relatively sedentary, into three groups who walked for 0, 75, 150, or 225 minutes a week for 26 weeks. (The current guidelines recommend the equivalent of 150 minutes per week of moderate exercise.) The subjects completed a battery of 16 cognitive tests in five domains (Verbal Memory, Visuospatial Processing, Simple Attention, Set Maintenance and Shifting, and Reasoning) before and after the walking program.
The good news for those who don’t get much exercise: even just 75 minutes a week - half the recommended dose - was enough to boost Simple Attention and Visuospatial Processing. Doing more exercise didn’t produce further gains in Simple Attention, but there was a dose-response effect in Visuospatial Processing, with the 225-minute group scoring highest. So overall, it does appear that even a little bit of exercise helps, and more is better.
The most interesting finding, from my perspective, is that the best predictor of how much any individual subject gained wasn’t how long they exercised for; it was how much their aerobic fitness, as measured by VO2 max, increased. This suggests that some of the same mechanisms are responsible for both the physical and cognitive gains that result from exercise, so the best way to boost your brain is to do whatever gives your VO2 max the biggest boost.
One caveat to keep in mind is that the exercise used in this study was walking on a treadmill (which make the intensity and duration easier for the researchers to monitor). Would the results have been different if they’d gone for a walk outside? There’s an interesting body of research showing the cognitive benefits of walking through a natural environment, independent of whatever physical effects you get. It seems to me the takeaway is to get as fit as you can, and do as much of it outside as possible - do that, and you should stay razor-sharp.