We investigated the impact of viewing versus not viewing a real forest on human subjects’ physiological and psychological responses in the same setting. Fifteen healthy volunteers (11 males, four females, mean age 36 years) participated. Each participant was asked to view a forest while seated in a comfortable chair for 15 min (Forest condition) vs. sitting the same length of time with a curtain obscuring the forest view (Enclosed condition). Both conditions significantly decreased blood pressure (BP) variables, i.e., systolic BP, diastolic BP, and mean arterial pressure between pre and post experimental stimuli, but these reductions showed no difference between conditions. Interestingly, the Forest viewing reduced cerebral oxygenated hemoglobin (HbO₂) assessed by near-infrared spectroscopy (NIRS) and improved the subjects’ Profile of Mood States (POMS) scores, whereas the Enclosed condition increased the HbO₂ and did not affect the POMS scores. There were no significant differences in saliva amylase or heart rate variability (HRV) between the two conditions. Collectively, these results suggest that viewing a real forest may have a positive effect on cerebral activity and psychological responses. However, both viewing and not viewing the forest had similar effects on cardiovascular responses such as BP variables and HRV.

We investigated the influence of forest management on landscape appreciation and psychological restoration in on-site settings by exposing respondents to an unmanaged, dense coniferous (crowding) forest and a managed (thinned) coniferous forest; we set the two experimental settings in the forests of the Fuji Iyashinomoroi Woodland Study Center. The respondents were individually exposed to both settings while sitting for 15 min and were required to answer three questionnaires to analyze the psychological restorative effects before and after the experiment (feeling (the Profile of Mood States), affect (the Positive and Negative Affect Schedule), and subjective restorativeness (the Restorative Outcome Scale). To compare landscape appreciation, they were required to answer another two questionnaires only after the experiment, for scene appreciation (the semantic differential scale) and for the restorative properties of each environment (the Perceived Restorativeness Scale). Finally, we obtained these findings: (1) the respondents evaluated each forest environment highly differently and evaluated the thinned forest setting more positively; (2) the respondents’ impressions of the two physical environments did not appear to be accurately reflected in their evaluations; (3) forest environments have potential restorative effects whether or not they are managed, but these effects can be partially enhanced by managing the forests.

Repeated bouts of ischemia followed by reperfusion, known as ischemic preconditioning (IPC), is found to improve exercise performance. As redistribution of blood from the inactive areas to active skeletal muscles during exercise (i.e., functional sympatholysis) is important for exercise performance, we examined the hypothesis that IPC improves functional sympatholysis in healthy, young humans. In a randomized study, 15 healthy young men performed a 10‐min resting period, dynamic handgrip exercise at 10% maximal voluntary contraction (MVC), and 25% MVC. This protocol was preceded by IPC (IPC; 4 × 5‐min 220‐mmHg unilateral occlusion) or a sham intervention (CON; 4 × 5‐min 20‐mmHg unilateral occlusion). Near‐infrared spectroscopy was used to assess changes in oxygenated hemoglobin and myoglobin in skeletal muscle (HbO2 + MbO2) in response to sympathetic activation (via cold pressor test (CPT)) at baseline and during handgrip exercise (at 10% and 25%). In resting conditions, HbO2 + MbO2 significantly decreased during CPT (−11.0 ± 1.0%), which was significantly larger during the IPC‐trial (−13.8 ± 1.2%, P = 0.006). During handgrip exercise at 10% MVC, changes in HbO2 + MbO2 in response to the CPT were blunted after IPC (−8.8 ± 1.5%) and CON (−8.3 ± 0.4%, P = 0.593). During handgrip exercise at 25% MVC, HbO2 + MbO2 in response to the CPT increased (2.0 ± 0.4%), whereas this response was significantly larger when preceded by IPC (4.2 ± 0.6%, P = 0.027). Collectively, these results indicate that IPC‐induced different vascular changes at rest and during moderate exercise in response to sympathetic activation. This suggests that, in healthy volunteers, exposure to IPC may alter tissue oxygenation during sympathetic stimulation at rest and during exercise.

“Forest bathing” can evoke positive physiological responses and relieve stress. We investigated how restoration from a stress stimulus is affected by forest management and an individual’s personal traits. For the study, we recruited 17 males and took them to either an unmanaged forest (UF) with densely packed trees or a managed forest (MF) with improved light and visibility. We assessed their personality traits and depressive tendencies by the NEO Five-Factor Inventory and Beck Depression Inventory, respectively. The participants performed a static hand grip stress exercise for 2 min at 30% of maximal voluntary contraction, and viewed the forest for 15 min. Their blood pressure (BP) and saliva cortisol increased after the stimulus but then significantly decreased after viewing, with significantly lower levels in the MF than in the UF (p < 0.05). Their heart rate (HR) remained unchanged throughout viewing, irrespective of the forest condition. The ratio of low-frequency to high-frequency HR variability, indicative parasympathetic nerve activity, significantly increased by the last 5 min of viewing in the UF (p < 0.05), whereas it decreased in the MF. Difference in systolic BP between after the stimulus and after viewing was related to neuroticism and depression scores in the UF, but not in the MF. These findings provide useful information for the future application of forest management and indicate that an MF may have greater beneficial effects than a UF for restoration from physiological stress and that these positive effects may be partly related to individual personal traits.

Energy expenditure (EE) during treadmill walking under normal conditions (normobaric normoxia, 21% O₂) and moderate hypoxia (13% O₂) was measured. Ten healthy young men and ten healthy young women walked on a level (0°) gradient a range of speeds (0.67–1.67 m s⁻¹). During walking, there were no significant differences in reductions in arterial oxygen saturation (SpO₂) between the sexes. The hypoxia-induced increase in EE, heart rate (HR [bpm]) and ventilation ( $${\dot{{\rm{V}}}}_{{\rm{E}}}$$V ̇ E [L min⁻¹]) were calculated. Using a multivariate model that combined EE, $${\dot{{\rm{V}}}}_{{\rm{E}}}$$V ̇ E , and HR to predict ΔSpO₂ (hypoxia-induced reduction), a very strong fit model both for men (r² = 0.900, P < 0.001) and for women was obtained (r² = 0.957, P < 0.001). The contributions of EE, VE, and HR to ΔSpO₂ were markedly different between men and women. $${\dot{{\rm{V}}}}_{{\rm{E}}}$$V ̇ E and EE had a stronger effect on ΔSpO₂ in women ( $${\dot{{\rm{V}}}}_{{\rm{E}}}$$V ̇ E : 4.1% in women vs. 1.7% in men; EE: 28.1% in women vs. 15.8% in men), while HR had a greater effect in men (82.5% in men and 67.9% in women). These findings suggested that high-altitude adaptation in response to hypoxemia has different underlying mechanisms between men and women. These results can help to explain how to adapt high-altitude for men and women, respectively.