Neuroscientists uncover a previously unknown brain benefit of very slow running

A recent study published in Imaging Neuroscience indicates that engaging in a very slow jog for just ten minutes can improve a person’s mood and enhance their ability to focus. The research suggests that the gentle, rhythmic bouncing of running at a low intensity provides a measurable boost to brain regions involved in mental control and emotional regulation.

Human beings have a long evolutionary history of running, a form of movement that provides widespread physical and mental health benefits. The prefrontal cortex, a brain area located behind the forehead that is responsible for complex thinking and emotional control, appears particularly responsive to aerobic exercise.

Earlier work has shown that different forms of activity can stimulate this brain region. For example, a 2014 study revealed that even very mild, low-effort pedaling on a stationary bike is enough to activate the prefrontal cortex and improve mental focus. Building on that concept, researchers later found that a 2021 study of a ten-minute session of moderate-intensity running boosts mood and strongly activates the same brain areas.

But moderate running can be physically taxing, elevating the heart rate to a level that might feel uncomfortable or stressful for older adults or people who are not regularly active. This research progression led scientists to wonder if the gentlest possible jog could still deliver these same brain and mood benefits without the physical strain.

The research was led by Hideaki Soya, a professor emeritus at the Institute of Health and Sport Sciences at the University of Tsukuba, and Ryuta Kuwamizu, an assistant professor at the university, alongside Chorphaka Damrongthai and colleagues at the Soya Laboratory. “Running is widely believed to benefit the brain, but studies combining rigorous brain imaging with tightly controlled running protocols have been relatively limited, partly because exercise intensity is much easier to control on a bike,” Soya and Kuwamizu told PsyPost.

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The researchers wanted to test running under controlled laboratory conditions at the very bottom of the intensity range, using speeds that could also be used for walking. “If the benefits were still present at such a low intensity, running could become accessible to people who cannot, or simply do not want to, run hard,” they explained.

To measure mental performance, the researchers focused on executive function, a term for the mental skills that help people pay attention, manage time, and switch focus. They were especially interested in whether the physical characteristics unique to running, such as the vertical bouncing of the head with each step, might play a role in how the exercise affects the brain.

To explore this question, the researchers recruited 24 healthy young adults. Each participant completed two separate sessions on different days. One session involved sitting quietly on a treadmill for ten minutes to serve as a resting control condition, while the other session involved running on the treadmill at a very slow pace for ten minutes.

The researchers tailored the running speed to each person’s fitness level, ensuring it remained at a very light intensity. For the men in the study, this averaged about 3.4 miles per hour, and for the women, it averaged about 2.4 miles per hour. These are speeds that most people could comfortably walk, but the participants were instructed to maintain a running form with small steps.

Before and after each session, participants completed a brief survey assessing their mood on two dimensions: arousal and pleasure. They also completed a computer-based task called the Stroop test to measure their executive function. The Stroop test asks participants to look at color words, such as the word “RED,” printed in an unmatched color like blue ink, and then quickly identify the ink color rather than the written word. This creates a mental conflict, and the extra time it takes to answer correctly is a measure of cognitive interference.

To observe brain activity, the researchers used functional near-infrared spectroscopy. This non-invasive imaging technique uses light sensors placed on the scalp to measure changes in blood oxygen levels in the brain. Because exercise can cause changes in skin blood flow and heart rate that might interfere with these readings, the researchers waited five minutes after the running session before measuring brain activity.

During a separate two-minute run, the team also attached a small sensor to the participants’ heads to measure vertical head acceleration. This allowed them to capture the rhythmic bouncing motion of the participants’ steps.

The researchers found that the ten-minute slow run provided noticeable benefits compared to the resting session. Participants reported feeling more energetic and experiencing a more pleasant mood after the very light run.

“Notably, the increase in pleasant mood was particularly strong, suggesting that slow running may be especially effective at improving how people feel,” the researchers noted. They were surprised to see that the increase in pleasant mood appeared particularly pronounced compared with what they had observed with very-light-intensity pedaling in their previous studies.

Performance on the Stroop test also improved. Following the slow run, participants reacted faster to the conflicting color words, which suggests a temporary sharpening of their executive function and focus.

The brain imaging data supported these behavioral changes. After the slow run, the researchers saw increased blood oxygen levels in specific left-sided areas of the prefrontal cortex while participants completed the Stroop test. These specific regions, known as the dorsolateral prefrontal cortex and the frontopolar area, are heavily involved in overriding impulses and managing complex tasks.

When the researchers analyzed the head acceleration data, they noticed an interesting pattern. The amount of vertical bouncing a participant experienced during their run positively correlated with how much their pleasant mood increased. This provides evidence that the physical sensation of rhythmic up-and-down motion might be one of the mechanical factors that make running feel enjoyable.

“Intriguingly, this increase in pleasant mood was correlated with the magnitude of each runner’s head acceleration, raising the possibility that the gentle bouncing rhythm characteristic of running may itself contribute to why running feels good,” the researchers said. “Importantly, this head acceleration reflects the rhythmic vertical motion of the whole body, rather than simply movement of the head.”

The practical significance of the study lies in its cost-benefit balance, demonstrating that a very easy, walking-compatible pace with very low physiological strain is sufficient to produce measurable improvements. “If you have avoided running because it seems too demanding, slow running may offer a very accessible way to begin,” Soya and Kuwamizu added.

The findings are in line with research covered by PsyPost in 2023, which found that a ten-minute bout of very light-intensity exercise dilated the pupils and was associated with increased left prefrontal cortex activation and better executive function. The current results also align with a study covered by PsyPost in 2024, which found that short bursts of light-intensity physical activity increased blood flow to the prefrontal cortex, though that earlier study tested brief desk movements in children without directly measuring cognitive performance.

As with all research, there are a few things to keep in mind regarding this study. The experiment involved a small group of healthy young adults, meaning the results might look different in older populations or those with specific health conditions.

“Please do not read this as ‘slow running is better than harder running’ or as a claim that everyone should switch to slow running,” the researchers cautioned. “For those who enjoy brisk or vigorous running, it remains an excellent form of exercise for body and brain.”

They emphasized that their point is about the floor, not the ceiling, showing that measurable brain benefits of running can already appear at its very lowest intensity.

The study also relied on brain imaging equipment that lacked short-separation channels, which are specialized sensors used to filter out superficial blood flow in the scalp. While the researchers used specific timing and analytical techniques to reduce this noise, future studies using more advanced sensors could help confirm that the observed signals originate entirely from within the brain.

Additionally, the researchers compared running only to a resting state. Because they did not include a walking condition at the same speed, it is difficult to completely separate the effects of the running motion from the general effects of being upright and moving.

The team noted that the relationship between head acceleration and pleasant mood is currently exploratory and correlational, meaning causality is not yet established. “By directly comparing running with walking, we aim to determine whether the rhythmic vertical acceleration characteristic of running contributes to changes in mood and brain function,” they said.

Looking ahead, the researchers plan to test slow running in populations who may benefit from it most, including older adults, people with low fitness, and those with depressive symptoms. They also hope to better understand the neural mechanisms through which slow running influences the brain, such as how it might engage arousal-related catecholaminergic systems—neural pathways involving dopamine and noradrenaline.

“Our long-term goal is to establish slow running as an evidence-based, easily accessible daily habit for maintaining mental and cognitive health across the lifespan,” they explained.

“Running is one of the most fundamental human movements, yet many people feel that it is not for them,” Soya and Kuwamizu concluded. “We are beginning to think that slow running may be more than simply running slowly. It may be a form of locomotion in which we move slowly while preserving the gentle, rhythmic vertical oscillation characteristic of running—and enjoy the pleasant ‘vertical groove’ created by that rhythm.”

The study, “Slow running benefits: Boosts in mood and facilitation of prefrontal cortex function even at very light intensity,” was authored by Chorphaka Damrongthai, Ryuta Kuwamizu, Yudai Yamazaki, Naoki Aoike, Dongmin Lee, Kyeongho Byun, Ferenc Torma, Kazuki Hyodo, Worachat Churdchomjan, Michael A. Yassa, Kazutaka Adachi, and Hideaki Soya.