Effects of Exercise Intensity Differences in Forest Therapy Programs on Immunoglobulin A and Dehydroepiandrosterone Levels in Older Adults

The purpose of this study was to examine the effects of exercise intensity and the duration of an exercise-based forest therapy program on physiological changes in older adults. The forest therapy program consisted of 20 sessions over 10 weeks. Forty-one older adults aged 65 years and older were divided into no treatment (daily activity group) and experimental (forest therapy) groups. The experimental group was further divided into the medium-intensity forest exercise group and the high-intensity forest exercise group to analyze physiological changes according to exercise intensity and duration. The physiological changes were analyzed by collecting saliva and measuring changes in the levels of immunoglobulin A and dehydroepiandrosterone, a hormone used to predict aging. Changes within the daily activity group and the forest therapy group after their respective exercises were analyzed using paired t-tests. Saliva testing was performed before and in weeks 5 and 10 of the program and analyzed using a repeated measures analysis of variance to assess the effects of the forest therapy on the medium-intensity forest exercise group and the high-intensity forest exercise group based on the duration of exercise. As a result of the study, a significant increase in immunoglobulin A was observed in the medium-intensity forest exercise group. The daily activity group and the high-intensity forest exercise group showed an increase, but there was very little change and no significance. Changes in dehydroepiandrosterone decreased in the daily activity group and significantly increased in the moderate-intensity forest exercise group at 5 and 10 weeks, showing that regular moderate-intensity forest exercise has an effect on dehydroepiandrosterone. The high-intensity forest exercise group improved over time, but no significant level of change was observed. This study shows that forest exercise has a beneficial effect on immunoglobulin A and dehydroepiandrosterone levels in older adults.