Tsukuba, Japan—A growing body of evidence shows that exercise improves mood and cognitive function. However, much of this evidence comes from cycling, which allows researchers to precisely control exercise intensity in the laboratory. Running may play a special role in this story: it is a fundamental human movement, closely linked to our evolutionary history, and remains a popular form of exercise practiced by millions of people worldwide. This raises two basic questions about running: does it provide similar benefits, and if so, how little running is enough?
To address these questions, the researchers used a treadmill to precisely control exercise intensity and functional near-infrared spectroscopy (fNIRS) to measure prefrontal cortical activity following 10 min of very slow running at approximately 3-6 km/h, a pace close to walking. This comfortable pace corresponds to a very light exercise intensity of approximately 35% of peak oxygen uptake (V̇o2peak).
The results were clear: after just 10 min of very slow running, participants showed a shorter Stroop interference time—a measure of executive function—and reported a more pleasant mood. Activity also increased in prefrontal regions associated with executive function and mood regulation, most notably the left dorsolateral prefrontal and left frontopolar cortices. Interestingly, greater up-and-down movement of the runner's head—the gentle vertical oscillation characteristic of running—was associated with a greater improvement in mood.
These findings suggest that even very slow running, despite imposing little physiological demand, can simultaneously improve mood and executive function while providing insight into the brain mechanisms that may underlie these effects.
Because it requires relatively little exertion, very slow running may be an accessible form of exercise, potentially benefiting people with low fitness levels or those who find conventional exercise challenging. A brief, comfortable run could provide a practical way to support physical and mental well-being while benefiting executive function. Notably, previous research has also shown that a 10-min bout of very light-intensity exercise can enhance hippocampal-dependent memory (Suwabe & Soya et al., PNAS, 2018), highlighting the broader potential of light-intensity exercise for cognitive function.
