# Green exercise
## Overview

There is growing interest in the theory and research about the physical and mental health benefits of green exercise (exercise in natural environments) as the psychobiological mechanisms involved.
There several meta-analyses which synthesise the findings in this area. They find that green exercise reduces negative mood; it less clear whether it enhances positive mood. The more natural the environment, the greater the benefits, but even short exposures (e.g., 10 minutes) can be effective.
A useful critique of theoretical and methodological issues in green exercise, with recommendations about ways forward, is provided by Laezza et al. (2024).
This page contains some notes and ideas for those interested in green exercise research.

## Goals

Goals of this resource page:
* Understand what "green exercise" is.
* Review the theoretical and empirical green exercise literature
* Document theories, models, and processes involved in the physical and psychology effects of "green exercise".
* Develop methodologies to better understand the potential benefits and mechanisms of green exercise.

## What is green exercise ?

"Green exercise is [physical] activity in the presence of nature." (Barton & Pretty, 2010, p. 3947)
Green exercise is physical activities undertaken whilst exposed to natural environments (Pretty et al., 2005).
Green exercise, in its simplest form, is physical exercise performed in (relatively) natural environments (Mackay & Neill, 2010.
Examples of green exercise:
* A walk in the park; perhaps the most iconic example of green exercise.
* Outdoor recreation activities such as cross-country running and mountain biking
* Water-based exercise activities such as open water swimming, canoeing, kayaking, rafting, and sailing.
* Gardening is a very common form of green exercise.
* Free movement and play in nature, such as sensual exploration of self in relation to natural surroundings (e.g., time at beach) is part of green exercise; it stimulates the senses, brain, and emotions

## Theory

Understandings the psychobiological effects of green exercise potential can draw on and test aspects of several different theories including:

### Common theories

* Biophilia,
* Evolutionary psychology
* Attention restoration theory
* Exercise psychology theories such as:
** Thermogenic hypothesis
** Cardiovascular conditioning

### What does "green" mean?

"Green" is a somewhat problematic term and interpretation of "green" warrants further consideration. "Green" is a proxy for "natural" - or the relatively absence of "artificial". But some natural environments are not green (e.g., blue, brown) and some environments are green but not natural (e.g., a room painted green).
"Greenness" can be conceptualised and measured:
* Objectively: e.g., Sugiyama et al. (2008) define “green” environments as vegetated areas such as parks, open spaces, and playgrounds.
* Subjectively: e.g., green exercise as exercise performed in environments with a greater ratio of natural to artificial elements than is typically encountered by that person in everyday life.
The green in green exercise is not meant literally, but rather figuratively to refer to the naturalness (vs. artificialness) of an environment. However, further conceptualisation and measurement of “greenness”, particularly as a psychological construct, however, remains underexplored (Bodin & Hartig, 2003).

### Motivation

* Theory of planned behavior (Flowers et al., 2017; Flowers, 2018)

## Research
### Systematic reviews and meta-analyses

Several systematic reviews and meta-analyses have examined the effects of green exercise on physical and mental well-being:
* Brito et al. (2021): This systematic review (49 studies) and meta-analysis (24 stuies) found that there are some exercise efficiency/efficacy benefits for nature-based outdoor vs. indoor (artificial) exercise environments.
* Barton and Pretty (2010): This multi-study analysis assessed the optimal duration and intensity of green exercise needed to enhance self-esteem and mood. The meta-analysis of 10 UK studies involving 1,252 participants found that short durations of green exercise yielded significant improvements in both self-esteem and mood, with diminishing but still positive returns for longer durations. All natural environments were beneficial, with the presence of water enhancing the positive effects. The study also noted variations across different demographics, with the mentally ill experiencing one of the greatest self-esteem improvements.
* Lahart et al. (2019): This systematic review assessed studies comparing outdoor green and virtual green exercise with indoor exercise which lacked nature exposure. The findings were inconclusive regarding the added benefits of outdoor or virtual green exercise over indoor non-green exercise.
* Li et al. (2022): This meta-analysis of 19 controlled trials with 1,662 participants examined the psychological benefits of green exercise in wild and urban greenspaces. The study found that green exercise reduced negative emotions such as anxiety, tension, anger, depression, and fatigue, while enhancing positive feelings like vigor, comfort, naturalness, and relaxation. Notably, exercise in wild environments was more effective than in urban greenspaces for improving vigor and comfort.
* Wicks et al. (2022): This systematic review and meta-analysis examined 33 studies about the psychological benefits of outdoor physical activity in natural versus urban environments. The study found that exercising in natural settings led to greater improvements in a variety of outcomes (including anxiety, fatigue, positive affect, and vigour) compared to urban environments.
These reviews highlight the need for more rigorous and long-term studies to conclusively determine the benefits of green exercise.

### Universities
#### University of Essex

A key researcher in the area of green exercise has been Professor Jules Pretty et al. at the University of Essex. Some studies are:
* Pretty et al. (2005)
* Pretty et al. (2007)
* Barton & Pretty (2010).
* Flowers et al., (2017); Flowers (2018)
* Wicks et al. (2022)
* See http://greenexercise.org for a summary of their research work.
Examples of UoE research:
(p. 16, http://www.healthyparkshealthypeoplecongress.org/images/stories/documents/hphp.pdf.pdf)
(Source: https://www.ideafit.com/body-mind-benefits-green-exercise-0/)

#### University of Canberra

* Mackay (2008) and Mackay and Neill (2010)
* Holgate (2010)
* Rugendyke (2012)

### Deakin University

* See Townsend et al.
* Townsend, M. & Ebden, M. (2006). 'Feel Blue, Touch Green': Final report of a project undertaken by Deakin University, Barwon Helath, Parks Victoria, Alcoa Angelsea, ANGAIR and Surf Coast Shire. Retrieved from http://www.interenvironment.org/cipa/Feel%20Blue,%20Touch%20Green.pdf

#### QUT

* See Brymer et al.
* Brymer, E., Cuddihy, T. F., & Sharma-Brymer, V. (2010). The role of nature-based experiences in the development and maintenance of wellness. Asia-Pacific Journal of Health, Sport and Physical Education, 1, 21-28.

## Research and discussion questions

Some possible research and/or discussion questions:
* What kind of green exercise do people in?
** Type of activity?
** Length of time?
** Location?
** Intensity?
** Alone or with others?
** How "green" (natural) is the exercise?
** Is it informally or formally organised?
* What happens to people when they participate in green exercise?
* How does a green exercise experience differ (if at all) from physical exercise in non-natural environments?
* What do people like about green exercise?
* What do people not like about green exercise?
* How much green exercise people ideally like to do?
* What do 'ideal' green exercise experiences look like?
** One-off?
** Regularly?
* What motivates green exercise?
** What enables/facilitates green exercise?
** What are the barriers to green exercise?
* What is the role of cognition during green exercise? e.g., what is the impact of using associative, dissociative, and environmental thinking during GE?