TABLE 1.
Characteristics of included studies
| Study & country | Study design | Sample size | Age (mean or range) ± 1SD | Gender | Type of activity | Social context | Duration/distance | Intensity | Natural environment | Urban environment | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Bodin and Hartig (2003) a Sweden | XOVR | 12 | 26–46 | 50% female | Running | Alone | 60 min (14 km) | Relaxed pace | Maintained path through pine‐birch forest, open fields and lakeside. | Medium‐density residential and commercial area. | |
| Bratman et al. (2015) America | RT | 70 | 24.1 (SD not published) | 53% female | Walking | Unspecified | 50 min | Unspecified ‘similar levels of exertion’ | Paved path through grassland with scattered shrubs and oak trees. | Busy street with multiple lanes of traffic. Some bushes and trees along sidewalk. | |
| Butryn and Furst (2003) America | XOVR | 30 | 31 ± 10.5 | All female | Running | Alone | 4 miles | Self‐rated comfortable pace | Highly vegetated route with occasional views of a creek | Industrial area near downtown with heavy vehicular and pedestrian traffic. | |
| DeBrito et al. (2019) America | XOVR | 24 | 49.3 ± 6.7 | 83% female | Walking | Alone | 50 min | Self‐paced | Unpaved trail including secluded areas surrounded by large trees, grassland areas and a pond. | Route with medium density traffic in a residential development area. | |
| Geniole et al. (2016) Canada | XOVR | 31 | 24.61 ± 3.9 | Males | Walking | Alone | 15 ± 3 min | Moderate comfortable pace | Regenerated landfill area, resembling green park, with visible methane release pipes | Business and commercial district with grass along most of the sidewalks | |
| Gidlow et al. (2016) UK | XOVR | 38 | 40.9 ± 17.6 | 39% female | Walking | Alone b | 30 min | Self‐paced | Country park within the city | Quiet residential streets with low levels of traffic compared with UK average. | |
| Han (2017) Taiwan | RT | 116 | 20.85 ± 1.1 | 55% female | Walking & jogging | Unspecified | 15 min | Low (walking) or moderate (jogging) | Natural road lined with vegetation | Built road with buildings lining both sides | |
| Hartig et al. (1991) America | RCT | 102 | 20 (SD not published) | 50% female | Walking | With a guide | 40 min | Intensity not specified | Park with stream and associated riparian habitat, some ornamental vegetation and chaparral flora | Centre of a large, well‐kept diverse urban area, with commercial and residential buildings | |
| Hartig et al. (2003) America | RT | 112 | 20.87 ± 3.7 | 50% female | Walking | With an assistant | 50 min | Low intensity | Well graded dirt track through 4000‐acre vegetation and nature reserve | Medium‐density professional office and retail development with visible landscaped areas. | |
| Hassan et al. (2018) China | XOVR | 60 | 19.6 ± 1.4 | 50% female | Walking | Alone | 15 min | Intensity not specified | Track through a well‐managed bamboo forest area | Urban area with many traditional buildings | |
| Johansson et al. (2011) Sweden | XOVR | 20 | 20–29 | 50% female | Walking | Alone & with a friend | 40 min | Brisk pace | Path through park passing open fields, gold course, river and landscaped area | City streets with moderate levels of traffic, low rise buildings of varying architecture and colour. | |
| Kinnafick and Thøgersen‐Ntoumani (2014) UK | XOVR | 30 | 25.86 ± 11.5 | 56% female | Walking | Alone | 15 min | Pace set by guide, but not specified | Park primarily made up of green space with small areas of woodland and a pond | Busy and built up commercially dominant area. | |
| Lyu et al. (2019) China | RT | 120 | 19–24 | 50% female | Walking | Groups of 30 | 15 min | Moderate intensity | 2× bamboo forests, 1 bamboo park | Centre of downtown area | |
| Ojala et al. (2019) Finland | XOVR | 88 | 48.31 ± 8.6 | 100% female | Walking | Groups of up to 4 | 30 min | Slow walking, paced by guide | 1 × 1000 ha urban woodland, with diverse animal and plant life; 1× constructed urban park, with water and recreational features. | City Centre with heavy traffic, museums, shopping and traffic Centre. | |
| Perkins et al. (2011) America | RT | 26 | 19–24 | 73% female | Walking | Groups of 2–4 | 20 min | Moderate pace | Wooded trail, partially snow covered | Residential area and parking lot | |
| Roe et al. (2011) Scotland | XOVR | 11 c | 46 (SD not published) | 64% female | Walking | Groups of approx. 10 | 60 min | Intensity not specified | 70 ha park with woodland, wilderness and parkland | Stirling town Centre with some greenery and historic interest | |
| Song et al. (2013) Japan | XOVR | 13 | 22.5 ± 3.1 | 100% male | Walking | Alone | 15 min | Intensity not specified | Urban park; trees had either lost their leaves or turned red or yellow. | City area around the urban park | |
| Song et al. (2014) Japan | XOVR | 17 | 21.2 ± 1.7 | 100% males | Walking | Alone | 15 min | Intensity not specified | Urban park; trees had light green leaves, and the azaleas were in full bloom | City area around the urban park | |
| Song et al. (2015) Japan | XOVR | 23 | 22.3 ± 1.2 | 100% males | Walking | Alone | 15 min | Intensity not specified | Urban park with hardwood trees and a large pond | City area around the park, including a residential area | |
| Song et al. (2018) Japan | XOVR | 624 | 27.1 ± 1.6 | 100% males | Walking | Alone | 15 min | Intensity not specified | 52× different safe and well‐maintained forest areas | 52× urban areas, either downtown or near a railway station | |
| Song et al. (2019) Japan | XOVR | 60 | 21 ± 1.3 | 100% female | Walking | Alone | 15 min | Participant's normal walking pace | 6× different well‐maintained forest areas | 6× urban areas, either downtown or near a railway station | |
| Stigsdotter et al. (2017) Demark | XOVR | 51 | 20–36 | 100% female | Walking | Groups of 4–5 | 15 min | Intensity not specified | Health forest (2 ha, diverse vegetation and rich nature) | Historical downtown area; varied historical and architectonical qualities, with few natural elements. | |
| Takayama et al. (2014) Japan | XOVR | 45 |
Mean age by group: 21.2 ± 0.8 20.8 ± 1.5 21.4 ± 1.3 21.1 ± 1.4 |
100% male | Walking | Alone | 15 min | Intensity not specified | 2× forests consisting of mainly Japanese cedar, and 2× forests consisting of Japanese and Sawtooth oak. | 4× downtown areas along major traffic roads or around the main station in each district | |
| Tyrväinen et al. (2014) Finland | XOVR | 95 | 47.64 ± 8.68 (based on final sample of 77) | 92% female (of the 77) | Walking | Group of up to 4 | 30 min | Slow walking speed | 1 × 20 ha. Urban park, including a water feature, flower beds and grass lawns. 1 × 1000 ha forest area, with mixed and conifer forests. | City Centre next to the main city street, with a few trees visible. | |
Abbreviations: RCT, randomised controlled trial; RT, randomised trial; XOVR, crossover design.
a
Participants ran twice in each condition.
b
Researcher followed one pace behind and asked for rating of exertion at 5 min intervals.
c
Only 11 participants from the good mental health group are considered.