Research on forest therapy and health outcomes is insufficient and involves the limited unification of various health indicators. Information on the natural therapeutic elements of forests and forest-therapy programs is insufficient. We investigated forest-therapy programs, the natural therapeutic elements of the forest environment, and health-outcome measures to standardize the health indicators of forest therapy. A systematic review was conducted on the health outcomes of forest therapy from 2010 to 2021. We summarized natural therapeutic elements and forest-therapy sites, characteristics, and health outcomes. Twenty-nine articles were analyzed. Among them, forest therapies of walking and physical activity were conducted most frequently. Additionally, a positive improvement in general sentiment condition was substantial in all vegetation environments, and a reduction in depression, psychological enhancement, stress alleviation; and an enhancement in the cardiovascular system and the endocrine system occurred in both narrow- and broad-leaved forests. Walking, five-senses stimulation, physical activities, and meditation benefited psychological and physiological outcomes. We evaluated natural therapeutic elements of the forest-environment program and health outcomes. This systematic review can be used as a reference for the planning and operation of forest-therapy programs.

(1) Background: Although interest in the health-promoting effects of forest therapy is increasing, few researchers have investigated the mid-long-term impact of such therapy on health indicators or exercise behaviors. We explored changes in physical health, mental health, and exercise behaviors 1, 2, and 4 weeks after a forest therapy program concluded. We sought to establish a solid foundation for such programs and a standardized evaluation system. (2) Method: We measured the blood pressure and heart rate variability of 99 adults before and after participation in a forest therapy program. We used the State-Trait Anxiety Inventory to assess anxiety, the Beck Depression Inventory to evaluate both anxiety and depression, the Profile of Mood States to explore mood, the Euro-Quality of Life-5 Dimension scale to assess the overall quality of life, and the Positive and Negative Effect Schedule to measure positive and negative mood. We employed the Global Physical Activity Questionnaire to determine exercise time, intensity, and changes in exercise type before the program and 1–4 weeks after program completion. (3) Results: Anxiety, depression, mood, quality of life, heart rate, and blood pressure control improved significantly after the program. The reduced depression and increased medium-intensity exercise time persisted for 1, 2, and 4 weeks after the end of the program. (4) Conclusions: We tracked various health indicators and clearly distinguished those that were useful in the short term from those more appropriate for evaluation in the long term. This is the first report to show that a forest therapy program affects exercise behavior; this suggests that health behaviors should be continuously tracked.

Research is increasingly focusing on the health-promoting effects of forest healing programs. A number of different health indicators are in use, necessitating the establishment of standardized health measurement tools and protocols for forest healing. Also, it is necessary to improve the indicators and protocols by incorporating the opinions of program participants and instructors, so we conducted a qualitative analysis based on focus group interviews (FGIs) and in-depth interviews (IDIs). We collected opinions through interviews conducted for about 1 h with 32 participants in the pilot study and three instructors of the forest healing program. We utilized the MAXQDA program, commonly employed for qualitative research, such as coding and analyzing interview transcripts and literature reviews, as part of the qualitative research process. Three researchers coded and categorized the data, and the first author and corresponding author performed the final coding and categorization. Opinions on the five mental health questionnaires, three physical health measures, and exercise behavior measures used in the forest healing program were solicited. Opinions on the measurement protocol were also solicited. Participants faced challenges in completing the mental health questionnaire due to inappropriate terminology, difficulty in providing truthful responses due to repetitive questions, and the complexity of answering exercise-type questions due to the length of the survey and the absence of clear examples. It was identified that improvements are needed in the future. Some participants commented on the need to measure blood circulation and short-term health changes, and others noted that performing measurements in large groups was difficult, such that there was a need to introduce a measurement protocol for groups. This study is the first to qualitatively evaluate the validity of health measurement tools associated with forest therapy programs. It can contribute to the establishment of standardized health indicators and protocols, as well as serve as a valuable reference for selecting measurement tools to evaluate the effectiveness of forest healing interventions.