An experimental study found that exercising in the presence of nature — even virtual nature — offers psychological benefits compared to exercising without. The study, published in the International Journal of Psychophysiology, further pinpointed areas of the brain that may be responsible for these effects.
Physical activity is a known stress-reducer that may even be able to lower a person’s mental health risk. Research suggests that exercising in natural environments, called “green exercise”, is especially beneficial since it is experienced as more enjoyable, relaxing, and easier to stick to compared to indoor exercise. Some evidence suggests that even the virtual presence of nature can produce these types of benefits.
While these findings suggest something special about the way our brains process nature, the neural mechanisms are unclear. The authors of the new study aimed to better understand these underlying mechanisms by exploring what happens in the brain when people take walks through nature.
“The reasons why we are so interested in making exercise a more pleasurable experience is mainly because of the stress levels that are currently experienced by most of us,” said study author Marcelo Bigliassi, an assistant professor of psychophysiology and neuroscience at Florida International University.
“We are aware of the benefits of green exercise, but the reality is that we don’t know much about what is going on in the brain when we exercise in the presence of nature. Most of the psychological and perceptual responses reported in our study were expected to a certain extent, but we were also trying to unravel the brain mechanisms underlying those emotional states.”
The study participants were 17 women and 13 men with an average age of 24. The subjects were randomly assigned to three different conditions in counterbalanced order. During each condition, participants were instructed to walk for ¼ mile at their own pace.
In the green exercise condition, participants walked on a campus trail that was surrounded by trees, greenery, and natural sounds. In the virtual green exercise condition, participants walked indoors on a treadmill while watching and listening to a video of the campus trail route. In the control condition, participants walked indoors on a treadmill in front of a white wall.
Throughout the walks, brain activity was monitored via an electroencephalography (EEG) cap fit to the participant’s head and heart rate variability was monitored via a heart rate monitor attached to the chest. At the beginning, halfway through, and at the end of each walk, the participants rated their attentional focus (internal to external), their feeling (very bad to very good), and arousal (low to high).
For the most part, both the green exercise and virtual green exercise had significant effects on the measures of the study. However, the effects tended to be strongest for the green exercise.
Compared to the control condition, the green exercise condition elicited more positive affect and more emotional awareness. The green exercise condition, and to a lesser extent the virtual green exercise condition, also helped participants reallocate their attention externally. This is notable because focusing on the present moment tends to be helpful in reducing anxiety symptoms. Both the green exercise and virtual green exercise were rated as more enjoyable compared to the control condition.
Interestingly, in the green exercise condition, participants completed the walk faster compared to the other two conditions. This could be because participants were more focused on the present moment, and focusing on thoughts of the past and future has been found to compromise movement execution. Additionally, being in nature leads to feelings of calm which may help to improve control of automatic movements.
Along with the speedier pace, the green exercise elicited higher physiological stress, as indicated by increased heart rate and heart rate variability. Notably, although physiological stress was increased, participants in the green exercise condition experienced the most affective benefits. This suggests that the presence of nature was able to counter the additional stress of the green exercise.
“The main takeaway from this study is that, if you have a couple of minutes to spare in your day to unwind, spending that time outdoors will maximize those results,” Bigliassi told PsyPost. “Your brain will react positively to that experience, although you might not be completely aware of that. Walking at light intensity for just 5 or 6 minutes in the presence of nature can really upregulate those low-frequency waves in the brain and improve connectivity of several regions that will make you feel more relaxed.”
The findings further shed light on the potential brain mechanisms responsible for these effects. The green exercise condition was associated with greater connectivity in the frontal and parietal brain regions. There was also an upregulation of low-frequency waves throughout the cerebral cortex, which the study authors say is associated with “the default mode network and a state of relaxation, wherein individuals are more aware of their surroundings and emotional states.”
The findings suggest that exercising in the presence of nature offers stronger psychological and physiological benefits than exercising without it. Moreover, virtual nature can produce some of these benefits, though to a lesser degree than real natural environments.
“We were really surprised about the effect size that we observed with such a short intervention,” Bigliassi said. “The changes in the brain’s electrical activity and functional connectivity were substantial, although participants only spent around 5 minutes walking outdoors. This could have very serious implications for the mental wellbeing of individuals working in high-stress environments (i.e., all of us?).”
But the study, like all research, includes some caveats.
“We are still trying to understand whether we can have similar results with virtual reality, although this technology can only elicit partial environmental sensory stimulation (i.e., visual and auditory),” Bigliassi told PsyPost. “In addition, moving away from your work environment, even if just for a couple of minutes, may induce a feeling of tranquility. We have now sufficient reasons to believe that the effects of augmented reality and virtual reality will almost always be less pronounced than ‘real-life’ interventions.”
“I would like to thank my graduate student, Ms. Angeliki M. Mavrantza and research collaborator, Dr. Giovanna Calogiuri for their assistance throughout the process,” Bigliassi added. “This was a very complex study in terms of data collection, signal processing, and interpretation, which was only successfully conducted because we worked as a cohesive team from beginning to end.”
The study, “Psychophysiological mechanisms underlying the effects of outdoor green and virtual green exercise during self-paced walking”, was authored by Angeliki M. Mavrantza, Marcelo Bigliassi, and Giovanna Calogiuri.
