Research has shown that exercise in natural environments – sometimes referred to as “green exercise” – promotes physical and psychological health. What is not known, however, is whether the degree of nature in the exercise environment makes a difference in the extent of benefits received. This study explored the possibility of a nature gradient, where the cognitive and psychological benefits of exercise would increase with the amount of nature in the exercise environment.
This study was conducted in Australia with 90 adolescents (age 14-15) participating in one of four groups. The groups were randomized to one of the following conditions: a non-exercise indoor control, indoor exercise, park exercise, and nature reserve exercise. On separate days, each of the groups traveled from their school to their respective locations. Participants in the three exercise groups completed assessments immediately before and after a 20-minute exercise routine in the environment of their experimental condition. Participants in the non-exercise group completed the same assessments before and after working on an indoor, non-physical activity project. The assessments included two measures of cognition: one focusing on sustained attention; the other, on working memory. The psychological assessment included self-report measures of stress, affect, and vitality.
Data analyses examined changes within and between groups. Each group improved in sustained attention, with the indoor group showing greater changes than the park group. None of the groups reported meaningful changes in affect. The park group showed greater changes in vitality than the control (no exercise) group. There were no between-group differences in working memory. These mixed results do not support the idea that cognitive and psychological outcomes would improve in accordance with the degree of nature present in the exercise environment. One possible explanation for the lack of support for the “nature gradient” hypothesis relates to the fact that students in the exercise groups reported low stress and scored highly on cognitive measures prior to their exercise routine. Low levels of perceived stress prior to exercise leaves little room for stress reduction. Likewise, high pre-test cognitive results limit the capacity for the intervention (exercise) to produce observable changes in the related outcomes.
Research on green exercise has largely focused on the effects of walking in urban green environments. Studies examining which combinations of environment (forest, park, beach, etc.) and exercise (walking jogging, group vs. individual, etc.) are limited. Further research in this area is warranted. Additionally, the relative contributions of exercise and nature exposure to cognitive and psychological benefits during green exercise remain unclear. Further research is necessary to address these and other gaps in our understanding of the benefits of green exercise.
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