Effect of Forest Walking on Autonomic Nervous System Activity in Middle-Aged Hypertensive Individuals: A Pilot Study

Abstract

There has been increasing attention on the therapeutic effects of the forest environment. However, evidence-based research that clarifies the physiological effects of the forest environment on hypertensive individuals is lacking. This study provides scientific evidence suggesting that a brief forest walk affects autonomic nervous system activity in middle-aged hypertensive individuals. Twenty participants (58.0 ± 10.6 years) were instructed to walk predetermined courses in forest and urban environments (as control). Course length (17-min walk), walking speed, and energy expenditure were equal between the forest and urban environments to clarify the effects of each environment. Heart rate variability (HRV) and heart rate were used to quantify physiological responses. The modified semantic differential method and Profile of Mood States were used to determine psychological responses. The natural logarithm of the high-frequency component of HRV was significantly higher and heart rate was significantly lower when participants walked in the forest than when they walked in the urban environment. The questionnaire results indicated that, compared with the urban environment, walking in the forest increased “comfortable”, “relaxed”, “natural” and “vigorous” feelings and decreased “tension-anxiety,” “depression,” “anxiety-hostility,” “fatigue” and “confusion”. A brief walk in the forest elicited physiological and psychological relaxation effects on middle-aged hypertensive individuals.

Relaxation Effect of a 2-Hour Walk in Kumano-Kodo Forest

“…Similar results are obtained even after only about 15 to 20 minutes of walking in the forest [8][9][10][11][12]. This highlights the importance of green spaces in the city [14] and garden walking [15].…”

“…These studies measured cortisol in saliva, sympathetic and parasympathetic functions, blood pressure, and heart rate variability as indices of stress. Some studies have included walking in addition to spending time in forests, but with walking times as short as 15 minutes [8][9][10][11][12].…”

The tree-species-specific effect of forest bathing on perceived anxiety alleviation of young-adults in urban forests

“…Although few studies have focused on this issue, studies about forest bathing suggested that the significant effect on mental restoration also accompanied by hard-wood species of oak (Park et al 2007, Lee et al 2009, Han et al 2016) and maple (Lee et al 2014, Song et al 2015b, Han et al 2016). In addition, more studies suggested that the forest bathing effect on anxiety alleviation was accompanied by coniferous tree species, such as Japanese cypress (Chamaecyparis obtusa) (Lee et al 2014, Song et al 2015a, Zhang et al 2015, Song et al 2016) and pine (Pinus spp.) (Sonntag-Öström et al 2015a, b, Chun et al 2016, Han et al 2016).…”

Evaluations of Landscape Locations along Trails Based on Walking Experiences and Distances Traveled in the Akasawa Forest Therapy Base, Central Japan

“…Differences in the biophysical and environmental features of forests are the essential reasons for variations in landscape evaluation [16,19,20,30,[32][33][34]38,45]. Based on several previous studies [1,8,9,12,[18][19][20]38,46] and our previous research [42], 16 parameters related to landscape attributes and respondents' perceptions were assigned to three categories-impressions, behavior, and overall evaluation (Table 2)-were investigated to describe the landscape quality of the four locations and to analyze the effects of walking distance and experience on evaluation. The first group of questions addressed respondents' impressions of the forest landscape based on their senses, including vision, hearing, and touch.…”

“…Previous studies have shown that the activity of walking in a forest can relieve stress caused by an individual's work or life [10][11][12]. In addition, forests contributed to patients' recovery [13].…”