Does participating in physical activity in outdoor natural environments have a greater effect on physical and mental wellbeing than physical activity indoors? A systematic review.
Level 1 - systematic review of randomized trials
Systematic review of controlled trials (randomized and non-randomized)
PubMed 21291246 · doi:10.1021/es102947t
What was done
A systematic review was conducted across multiple databases (including Medline, Embase, PsycINFO, and Cochrane) through June 2010. Eligible studies were controlled trials (randomized and non-randomized) comparing outdoor exercise initiatives to indoor exercise in adults or children that reported at least one physical or mental wellbeing outcome. Study quality was appraised, and findings were synthesized narratively due to study heterogeneity.
What was found
Eleven trials comprising 833 adult participants were identified; 6 trials (523 adults) were in young student populations. All interventions consisted of a single bout of walking or running indoors compared to the same activity outdoors. Most trials (n = 9) reported improvements on at least one mental wellbeing measure for outdoor exercise, showing increases in revitalization, positive engagement, and energy, along with reductions in tension, confusion, anger, and depression. However, outdoor exercise was associated with decreased feelings of calmness. Participants reported higher enjoyment, satisfaction, and intent to repeat outdoor activity. No trials evaluated physical wellbeing outcomes or long-term adherence. The abstract reports no numerical effect sizes or p-values.
Why it matters
This review provides evidence that acute bouts of exercise in natural environments may yield immediate psychological advantages over indoor workouts. It also establishes that empirical evidence regarding physical health benefits and long-term exercise adherence from green exercise remains largely unstudied.
Limits
All included studies examined only single-episode exercise bouts, precluding conclusions about sustained effects or behavioral adherence. Study quality was poor with sparsely reported methods and entry criteria. Outcome assessment was highly heterogeneous (13 distinct mental wellbeing instruments across 11 studies), no physical health outcomes were measured, and the study population was predominantly young students.
Cited by
- supports Studies comparing indoor versus outdoor exercise indicate that performing the same exercise outdoors produces greater health benefits.