Sustained effects of a forest therapy program on the blood pressure of office workers

•Sustained effects of a forest therapy program on blood pressure were investigated.•Office workers participated in a 1-day forest therapy program from 9:00 to 15:00.•Tests were conducted 3 days before, during, and 3 and 5 days after the program.•Blood pressure decreased during the program and was maintained for 5 days.•The program induced physiological relaxation effects in the office workers.

We examined the sustained effects of a forest therapy program on the blood pressure of office workers. Twenty-six office workers (mean age ± standard deviation, 35.7 ± 11.1 years) participated in a 1-day forest therapy program. Systolic and diastolic blood pressure and pulse rate were used as measurement indices. The evaluations were performed three times before breakfast, lunch, and dinner 3 days before, during, and 3 and 5 days after the forest therapy program. Systolic and diastolic blood pressure significantly decreased during the forest therapy program relative to the value from 3 days before the program, and this decrease was maintained 3 and 5 days after the forest therapy program. There were no significant differences in pulse rate. We then specifically focused on nine participants whose systolic blood pressure was above 120 mmHg. For the measurement before dinner, the systolic blood pressure significantly decreased (from 133.8 to 116.6 mmHg) during the forest therapy program, and this decrease was maintained at 3 and 5 days after the program (126.4 and 124.0 mmHg, respectively). A significant decrease in diastolic blood pressure (from 88.6 to 77.1 mmHg) was observed during the forest therapy program. In conclusion, systolic and diastolic blood pressure decreased during the forest therapy program and these decreases were maintained for 5 days.