Table 2 Summary of the physiological outcome measures of the included studies
From: Effects of forest bathing on pre-hypertensive and hypertensive adults: a review of the literature
Reference/participants | Change in SBP (mmHg) | Change in DBP (mmHg) | Change in heart rate (bpm)/HRV (Inms2) | Change in pulse rate (bpm) | Change in other outcome measures |
|---|---|---|---|---|---|
Types of forest intervention: forest walking | |||||
Feng et al., 2017 [41]; hyper-tensive middle-aged men | After forest walking, SBP was significantly lower by 13.2% in the drug group and 8% in the non-drug group. | After forest walking: DBP was significantly lower by 15.3% in the drug group and by 10.7% in the non-drug group. | NA | NA | After forest walking, total cholesterol, HDL, LDL, TG, IMT, and BaPWV improved in the drug group and non-drug group. FMD and NMD were improved remarkably in the drug group and non-drug group. |
Lee and Lee, 2014 [33]; pre-hypertensive elderly women | Compared with city walking, SBP was lower by 10.26+/−13.11 mmHg (8.4%) after forest walks; compared with forest walking, SBP increased by 2.0+/−17.51 mmHg (2.6%) after city walks. | Compared with city walking, DBP was significantly lower by 9.93+/−11/15 mmHg (8.3%) after forest walking; compared with forest walking, DBP was unchanged after city walking. | NA | NA | Compared with city walking, CAVI was significantly lower by 0.42+/−0.72; and FEV1 and FEV6 were increased by 0.19+/−0.26 and 0.22+/−0.36, respectively compared with forest walking, CAVI, FEV1, and FEV6 were unchanged after city walking. |
Li et al., 2016 [34] hypertensive middle-aged men | No significant difference in systolic blood pressure between forest and urban walking | No significant difference in diastolic blood pressure between forest and urban walking | NA | Forest walking significantly reduced the subjects’ pulse rate by 6.9%. | After forest walking, the serum level of adiponectin was significantly greater than that of urban walking. Forest and urban walks reduced the level of urinary adrenaline, noradrenaline, and dopamine but had no effect on total cholesterol, LDL, HDL, RLP, EIA, blood glucose, serum insulin, and DHEA-S, hs-CRP. |
Mao et al., 2012 [23] hypertensive elderly people | After a 7-day forest walking trip, SBP decreased significantly by 8 mmHg (5.4%) compared with that of the city group; after a 7-day city walking trip, SBP showed little change compared with that of the forest walking group. | After a 7-day forest walking trip, DBP decreased significantly by 6 mmHg (7%) compared with that of the city group; after a 7-day city walking trip, DBP showed little change compared with that of the forest walking group. | Heart rate did not change in either of the two groups before and after the experimental intervention. | Pulse rate did not change in either of the two groups before and after the experimental intervention. | At the end of the 7-day trip, ET-1, Hcy, AGT, AT1, and AT2 levels were significantly lower in the forest group. There were no significant alterations in these factors in the city group. The serum IL-6 level in the forest group was lower in comparison with its baseline level. |
Song et al., 2015 [36]; hypertensive middle-aged men | NA | NA | Compared with urban walking, mHF was 10% higher in forest walking; compared with urban walking, mHR was 1.9% lower in forest walking. | NA | NA |
Yu et al., 2017 [45]; pre-hypertensive middle-aged and elderly people | Pretest: 129.9 ± 17.5 mmHg; post-test: 124.8 ± 16.5 mmHg; significantly lower by 3.9% after forest walking | Pretest: 85.3 ± 9.1 mmHg; post-test: 84.0 ± 8.1 mmHg; significantly lower by 1.5% after forest walking | No significant change in HF and LF/HF | Pretest: 73.9 ± 9.4 bpm; post-test: 71.4 ± 8.4 bpm; significantly lower by 3% after forest walking | NA |
Zhou et al., 2017 [46] hypertensive middle-aged men | After forest walking, SBP decreased by 24.6%; after walking around a highway, SBP decreased by 17%. | After forest walking, DBP decreased by 29.5%; after walking around a highway, DBP decreased by 2%. | After forest walking, HR decreased by 28%; after walking around a highway, HR decreased by 20%. | NA | After forest walking, triacylglycerol, total cholesterol, and cardiac functions improved significantly compared with walking around a highway. |
Types of forest interventions: sitting and viewing of landscapes in the forest | |||||
Song et al., 2017a [35]; hypertensive middle-aged men | NA | NA | Compared with the urban area, HRV was significantly higher by 30% in forest viewing; no significant difference between the two environments in LF/HF; compared with the urban area, HR was significantly lower by 3.5% in forest viewing | NA | NA |
Types of forest interventions: forest walking and viewing of landscapes in the forest | |||||
Lanki et al., 2017 [22]; pre-hypertensive middle-aged women | Walking in an urban forest was associated with a 1.9% increase in SBP; sitting and viewing the landscape in an urban forest was associated with no change in SBP; viewing and walking in an urban forest was associated with no change in SBP compared with viewing and walking in an urban park and in the city center | Walking in an urban forest was associated with a 2.5% increase in DBP; sitting and viewing the landscape led to lower DBP compared with sitting and viewing the landscape in an urban park and in the city center; viewing and walking in urban forest was associated with no change in DBP compared with viewing and walking in an urban park and in the city center | Walking in a forest was associated with a 5.4% lower heart rate and a higher HF by over 100%; viewing of landscapes in a forest area was associated with a 6.5% lower heart rate and a 25% higher HF after the intervention. | NA | NA |
Horiuchi et al., 2015 [32]; hypertensive middle-aged and elderly people | After forest walking, SBP decreased significantly by 11% and 5% in the responder group (> 5% MAP decrease) and non-responder group (< 5% MAP decrease), respectively | After forest walking, DBP decreased significantly by 5% in the responder group (> 5% MAP decrease) but was unchanged in the non-responder group (< 5% MAP decrease) | NA | NA | No improvement in salivary amylase (sAmy) was observed before and after forest walking in both the responder group and the non-responder group |
Types of forest interventions: forest therapy program | |||||
Ochiai et al.,2015b [42]; hypertensive middle-aged women (n = 6) | NA | NA | NA | Pretest: 73.1 ± 2.5 bpm; post-test: 69.1 ± 2.7 bpm; significantly lower after forest therapy by 4.67 bpm (5.4%) | Salivary cortisol concentration: pretest: 0.168 ± 0.020 μg/dL; post-test: 0.124 ± 0.009 μg/dL; significantly lower after forest therapy by 2.63 μg/dL |
Ochiai et al., 2015a [24]; pre-hypertensive middle-aged men | Pretest: 140.1 mmHg, post-test: 123.9 mmHg; significantly lower by 16.1 mmHg (11.5%) | Pretest: 84.4 mmHg; post-test: 76.6 mmHg ; significantly lower by 7.8 mmHg (9.2%) | NA | NA | Salivary cortisol concentration, pretest: 7.4 μg/dL; post-test:4.9 μg/dL significantly lower after forest therapy by 2.5 μg/dL; urinary creatinine correction, pretest: 13.1 μg/g creatinine; post-test: 11.0 μg/g creatinine; significantly lower after forest therapy by 2.1 μg/g creatinine |
Song et al., 2017b [43]; pre-hypertensive middle-aged adults; HT, n = 9, non-HT, n = 17 | 5 days after: decreased significantly by 3.5% (pre: 114.8 ± 2.7 mmHg; post: 110.7 ± 2.6 mmHg); higher than 120 mmHg group (n = 9): 5 days after: decreased significantly by 5.1% (pre: 128.4 ± 4.9 mmHg; post: 121.8 ± 4.6 mmHg) | 5 days after: Decreased significantly by 2.8% (pre: 75.0 ± 2.3 mmHg; post: 72.9 ± 2.1 mmHg); higher than 120 mmHg group (n = 9),5 days after: decreased significantly by 5.3% (pre: 86.6 ± 3.4 mmHg; post: 82.0 ± 3.4 mmHg) | NA | Pulse rate: no significant change | NA |
Sung et al., 2012 [44]; hypertensive elderly people | 8 weeks after: I, −12.0 ± 9.2 mmHg; C, 11.5 ± 19.9 mmHg; decreased by 9 % from the initial measurement in the forest group compared with the control group | 8 weeks after: I, no change; C, 1.3 ± 13.3; DBP did not show a significant change from the baseline, and self-measured SBP and DBP at week 4 and week 8 did not differ from the baseline measurements. | NA | NA | Salivary cortisol level: significantly reduced in the forest group by 0.03 μg/dL; in the control group, the salivary cortisol level increased slightly at the follow-up. |