We all love to hear good news about our favourite habits. Both nature hiking and forest bathing, from the Japanese Shinrin-Yoku meaning “diving into the atmosphere of the forest”, are touted as being excellent for one's health. Urban Singapore, more known for its skyline than its forested Central Catchment Area, provides some great opportunities to enjoy nature.
When it comes to health, what does the actual evidence say about hiking and nature, what are the benefits? In this article we review the evidence from a variety of studies, using meta-analyses (studies on collections of studies) where possible and showing other evidence that we feel is relevant.
As ever, please talk to your doctor, or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle; especially if you are under treatment. We provide links to the quoted and other relevant studies at bottom of page.
The Evidence for Nature Hiking
Mitten et al, 2016, stated perhaps what we all might know, that:
"The synergistic effect of physical activity and time spent in nature make hiking an ideal activity to increase overall health and wellness. Multiple benefits for health and general well-being accrue from a lifestyle enriched by regular time in nature, among them breathing air rich in beneficial organic compounds, physical activity, restoration, and social bonding. Benefits may be immediate, such as restoration, or transpire over time, such as decreased depression and overall physical health improvement.
In short, hiking is a cost-effective intervention that helps people to meet physical activity guidelines, and carries the added benefit of exposure to the natural environment."
Their comprehensive article is well worth a read - follow the link from the resources at bottom of page.
Oh B et al, 2017, found, while there was some risk of bias in the studies, that the following health benefits were demonstrated:
"This present review found that six randomised control trials reported promising therapeutic benefits of forest exposure on several physical and psychological conditions including
hypertension,
cardiac and pulmonary function,
immune function,
inflammation,
oxidative stress,
stress,
stress hormone,
anxiety,
depression,
and emotional response,
although outcomes of anxiety and depression had mixed results and some inflammatory biomarkers showed null results."
Mental Health and Hypertension, Studies from Japan
A 2019 Japanese study, Akemi Furuyashiki et al, concluded:
"The results of this study suggest that a session of approximately 2 hours of forest bathing as part of a 1-day outing in a forest environment can lead to improvements in physiological and psychological health in people of working age, as demonstrated by the decrease in blood pressure and the alleviation of negative psychological parameters after forest bathing.
Moreover, participants with depressive tendencies showed a greater improvement in many of the profile of mood states items after forest bathing compared to those who did not display depressive tendencies. This outcome is evidence that a 1-day forest bathing activity was particularly effective at enhancing the psychological wellbeing of working age people with depressive tendencies."
Ideno et al, 2017, also found that:
"This systematic review shows significant effects of the forest environments on a reduction in blood pressure. In particular, the forest environment has a larger effect on lowering SBP in people with high blood pressure and in middle-aged or older people compared with the non-forest environment."
Why is Nature Beneficial?
To quote Oh et al, 2017:
"It appears likely that the therapeutic benefit of forest therapy is multi-factorial. It may be induced by the complex ecosystem as a whole such as the green scenery, fresh air, sunlight, clean water, rocks, soil, soothing sounds of streams, waterfalls, birds, and natural aromas of trees, plants, and flowers."
Stier-Jarmer et al, 2021, had this to say "The question often arises as to whether the health mechanisms in European forests are equivalent or at least comparable to those in Asian forests. Forests with a closed canopy are comparable because they provide a special interior forest climate with reduced air temperature, high air purity and humidity, and special light conditions. These climatic factors are beneficial to health and relieve the respiratory tract and the thermoregulation system.
Another important factor is the peace and quiet in forests, which is essential for mental recovery in a time of acoustic stimulus overload in urban settings. It is assumed that the effect of biogenic volatile organic compounds (BVOC) emitted by trees and plants, such as phytoncides (also known as terpenes in German), has an influence on human health in terms of their anti-inflammatory, antioxidant, or neuroprotective activities. This has not yet been conclusively clarified scientifically, but the authors of a recent state-of-the-art review confirmed that inhaling forest VOCs can result in useful antioxidant and anti-inflammatory effects on the airways."
And perhaps a deeper underlying response involving colour is at work. Without access to the outdoors, lab research has shown that seeing green video landscapes during cycling is of greater benefit to mood (Akers et al, 2012) than seeing the same video in red, that provoked feelings of anger. So perhaps those scenes we see in science fiction movies set in space, where nature montages are played on the walls of rooms, really do have some foundation in science and reality.
Final Thoughts
If one has access to nature, hiking is one form of exercise that could, should, be part of everyone's health arsenal. When it comes to physical health, we would recommend that everyone meets the recommend guidelines for exercise, moderated to their own level of health and personal circumstances.
The World Health Organisation's guidelines state: “Adults aged 18–64 years should do at least 150–300 minutes of moderate-intensity aerobic physical activity; or at least 75–150 minutes of vigorous-intensity aerobic physical activity; or an equivalent combination of moderate- and vigorous-intensity activity throughout the week”. A good hike would count as moderate intensity exercise. And this is certainly true if, like for some - myself included - you to carry a backpack with a little weight in it for the additional benefit.
For our own mental health - even simply for enjoyment - we like take time during a hike to stop and soak in the sounds and smells of nature. To find a quiet spot and do some breathing exercises or a little meditation (read more here).
While we enjoy the exercise part of hiking, the soaking in the nature part is just as important!
For those of us in tropical Singapore, heat and proper hydration is important: carrying sufficient water and consuming it. How much water varies between individuals. It can be worthwhile to understand one's sweat rate, especially for when planning longer (greater than 1 hour) hikes.
From mental to physical to social health, hiking and exposure to nature seems to have it all. For most people, improving health is about finding motivation and prioritising self-care with an ultimate goal of taking action. If you want to take effective and targeted steps that fit into your unique lifestyle, The Whole Health Practice is here to help.
Whether your interest is healthspan and longevity, to beat chronic illness or to enhance your mental health and well-being, our consultations and programs deliver results that are tailored to your needs.
Our foundational Whole Health Consult identifies and prioritises the key factors - known and unknown - that affect health and wellbeing. It provides targeted recommendations tailored to you, the individual, and your unique lifestyle.
Stay Healthy,
Alastair
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Related Resources and Studies
Singapore:
Ong AD, Cintron DW, Fuligni GL. Engagement with nature and proinflammatory biology. Brain Behav Immun. 2024 Jul;119:51-55. doi: 10.1016/j.bbi.2024.03.043. Epub 2024 Mar 29. PMID: 38555989.
Huber D, Freidl J, Pichler C, Bischof M, Kiem M, Weisböck-Erdheim R, Squarra G, De Nigris V, Resnyak S, Neberich M, Bordin S, Zechner R, Hartl A. Long-Term Effects of Mountain Hiking vs. Forest Therapy on Physical and Mental Health of Couples: A Randomized Controlled Trial. Int J Environ Res Public Health. 2023 Jan 13;20(2):1469. doi: 10.3390/ijerph20021469. PMID: 36674227; PMCID: PMC9859399.
Bauer A, White ND. Time in Nature: A Prescription for the Prevention or Management of Hypertension. Am J Lifestyle Med. 2023 Mar 25;17(4):476-478. doi: 10.1177/15598276231165662. PMID: 37426730; PMCID: PMC10328205.
Stier-Jarmer M, Throner V, Kirschneck M, Immich G, Frisch D, Schuh A. The Psychological and Physical Effects of Forests on Human Health: A Systematic Review of Systematic Reviews and Meta-Analyses. Int J Environ Res Public Health. 2021 Feb 11;18(4):1770. doi: 10.3390/ijerph18041770. PMID: 33670337; PMCID: PMC7918603.
Linsell JD, Pelham EC, Hondula DM, Wardenaar FC. Hiking Time Trial Performance in the Heat with Real-Time Observation of Heat Strain, Hydration Status and Fluid Intake Behavior. Int J Environ Res Public Health. 2020 Jun 8;17(11):4086. doi: 10.3390/ijerph17114086. PMID: 32521686; PMCID: PMC7312660.
Looney DP, Santee WR, Hansen EO, Bonventre PJ, Chalmers CR, Potter AW. Estimating Energy Expenditure during Level, Uphill, and Downhill Walking. Med Sci Sports Exerc. 2019 Sep;51(9):1954-1960. doi: 10.1249/MSS.0000000000002002. PMID: 30973477.
Wen, Y., Yan, Q., Pan, Y. et al. Medical empirical research on forest bathing (Shinrin-yoku): a systematic review. Environ Health Prev Med 24, 70 (2019). https://doi.org/10.1186/s12199-019-0822-8
Hunter MR, Gillespie BW, Chen SY. Urban Nature Experiences Reduce Stress in the Context of Daily Life Based on Salivary Biomarkers. Front Psychol. 2019 Apr 4;10:722. doi: 10.3389/fpsyg.2019.00722. PMID: 31019479; PMCID: PMC6458297.
Furuyashiki A, Tabuchi K, Norikoshi K, Kobayashi T, Oriyama S. A comparative study of the physiological and psychological effects of forest bathing (Shinrin-yoku) on working age people with and without depressive tendencies. Environ Health Prev Med. 2019 Jun 22;24(1):46. doi: 10.1186/s12199-019-0800-1. PMID: 31228960; PMCID: PMC6589172.
Hansen MM, Jones R, Tocchini K. Shinrin-Yoku (Forest Bathing) and Nature Therapy: A State-of-the-Art Review. Int J Environ Res Public Health. 2017 Jul 28;14(8):851. doi: 10.3390/ijerph14080851. PMID: 28788101; PMCID: PMC5580555.
Oh B, Lee KJ, Zaslawski C, Yeung A, Rosenthal D, Larkey L, Back M. Health and well-being benefits of spending time in forests: systematic review. Environ Health Prev Med. 2017 Oct 18;22(1):71. doi: 10.1186/s12199-017-0677-9. PMID: 29165173; PMCID: PMC5664422.
Ideno Y, Hayashi K, Abe Y, Ueda K, Iso H, Noda M, Lee JS, Suzuki S. Blood pressure-lowering effect of Shinrin-yoku (Forest bathing): a systematic review and meta-analysis. BMC Complement Altern Med. 2017 Aug 16;17(1):409. doi: 10.1186/s12906-017-1912-z. PMID: 28814305; PMCID: PMC5559777.
Mitten D, Overholt JR, Haynes FI, D'Amore CC, Ady JC. Hiking: A Low-Cost, Accessible Intervention to Promote Health Benefits. Am J Lifestyle Med. 2016 Jul 9;12(4):302-310. doi: 10.1177/1559827616658229. PMID: 32063815; PMCID: PMC6993091.
Akers A, Barton J, Cossey R, Gainsford P, Griffin M, Micklewright D. Visual color perception in green exercise: positive effects on mood and perceived exertion. Environ Sci Technol. 2012 Aug 21;46(16):8661-6. doi: 10.1021/es301685g. Epub 2012 Aug 10. PMID: 22857379.
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