Combined Effect of Walking and Forest Environment on Salivary Cortisol Concentration

Summary & key facts

Researchers had 74 young men walk for 15 minutes in a forest and in an urban area. They measured saliva cortisol (a stress-related hormone) before and after each walk. Mean cortisol fell after the forest walk (from 9.70 to 8.37 nmol/L) but changed little after the urban walk (from 10.28 to 10.01 nmol/L). The data showed a statistically significant combined effect of walking plus environment on cortisol (interaction p < 0.001).

Key facts:

• Sample: 74 young male participants walked for 15 minutes in a forest and in an urban environment.
• Forest walk: mean salivary cortisol dropped from 9.70 to 8.37 nmol/L.
• Urban walk: mean salivary cortisol changed from 10.28 to 10.01 nmol/L.
• Statistical test: there was a significant interaction between environment and walking (p < 0.001).
• Proportion with decreased cortisol after forest-walking was 69%; this was slightly higher than the 60% who showed decreases after viewing forest scenes, but that difference was not statistically significant (p = 0.093).
• Measurements were salivary cortisol taken before and after each walk, so results reflect short-term change in this hormone.
• Participants were all young men; the study did not include women or older adults, which limits how generally the findings can be applied.

Abstract

We investigated the effects of walking in a forest environment on salivary cortisol concentrations. Seventy-four young male participants walked for 15 minutes in forested and urban environments, and saliva was collected before and after walking. Our previous study reported salivary cortisol concentrations after walking only. This study was aimed at clarifying the combined effects of walking and environment by comparing post-walking data with pre-walking data. Walking in a forest environment decreased mean cortisol concentration from 9.70 to 8.37 nmol/L, whereas walking in an urban environment barely changed mean cortisol concentration, from 10.28 to 10.01 nmol/L. Two-way repeated analysis of variance revealed a significant interaction effect between the environment and walking (p < 0.001) in addition to the main effects of each (p < 0.001 and p = 0.001, for walking and environment, respectively). For further analysis, the proportion of participants who exhibited decreased cortisol after forest-walking was compared with the previously reported proportion of participants who exhibited decreased cortisol after viewing forest landscapes. Although the proportion of positive responders was slightly higher after walking (69%) than it was after viewing (60%), this difference was not statistically significant (p = 0.093). The present study revealed a significant combined effect of walking and the environment on cortisol concentrations.

Topics

Stress Responses and Cortisol Urban Green Space and Health

Categories

Environmental Science Health, Toxicology and Mutagenesis Physical Sciences

Tags

Environmental science Internal medicine Medicine Saliva