A brief walk in the forest can elicit physiological and psychological relaxation effects in hypertensive middle-aged individuals, according to Japanese researchers. In a pilot study, twenty hypertensive participants were instructed to walk predetermined courses in forest and urban environments (as control). Course length, walking speed and energy expenditure were equal between the forest and urban environments. Heart rate variability (HRV) and heart rate were used to quantify physiological responses. The high-frequency component of HRV (which reflects cardiac parasympathetic modulation) was found to be significantly higher, and heart rate significantly lower, when participants walked in the forest compared with the urban environment. 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’.

Effect of forest walking on autonomic nervous system activity in middle-aged hypertensive individuals: a pilot study. Int J Environ Res Public Health. 2015 Mar 2;12(3):2687-99.