Teruhisa Komori, Masayuki Mitsui, Kenji Togashi, Jun Matsui, Takaya Kato, Daisuke Uei, Aritomo Shibayama, Katsuhiro Yamato, Hidehito Okumura and Fujihisa Kinoshita
Background: Studies have shown that walking in forests can have a relaxation effect, but the participants only walked for about 15 minutes.
Methods and findings: The study adopted an open crossover design, in which 22 healthy male volunteers were randomly assigned to two groups. The first group walked the Kodo forest course first and the urban course second, while the second group completed the walks in the reverse order. The Kodo course was 4 km from the foot to the pass and back, and took around 2 hours. The participants walked the urban course at an exercise intensity equal to that of the Kodo course. We used both physiological and psychological measures to examine the relaxation effect of walking. Salivary amylase concentrations significantly increased from the start to the end of the urban course, and were significantly higher at the end of the urban course than at the end of the Kodo course. Saliva cortisol concentrations decreased from the start to the end of both courses, and were significantly lower at the end of the Kodo course than the urban course. Analysis of the Profile of Mood State data showed significant decreases in “Tension-Anxiety”, “Depression-Dejection depression”, “Anger-Hostility” and “Confusion” after walking both courses, and a significant decrease in “Vigor” after the urban course. Visual analog scores were significantly higher on the Kodo course, but decreased significantly on the urban course. The electrocardiogram analysis showed no noticeable change in the HF component time series for the urban course, although it tended to be higher on the Kodo course than the urban course. The LF/HF ratio was slightly higher for the urban course than for the Kodo course throughout.
Conclusions: The physiological and psychological measures indicate that walking for 2 hours in the forest is effective for relaxation.
