A growing body of research is exploring the potential added health benefits of exercise when performed outdoors in nature versus indoors. This systematic review aimed to compare the effects of exercise in outdoor environments versus indoor environments on psychological health, physical health, and physical activity behaviour. We searched nine databases from inception to March 2021 for English language, peer-reviewed articles: MEDLINE, Embase, PubMed, Scopus, Web of Science, CINAHL, SportsDiscus, GreenFile, and CENTRAL. We included randomized and non-randomized trials that compared multiple bouts of exercise in outdoor versus indoor environments, and that assessed at least one outcome related to physical health, psychological health, or physical activity behaviour. Due to minimal outcome overlap and a paucity of studies, we performed a narrative synthesis. We identified 10 eligible trials, including 7 randomized controlled trials, and a total of 343 participants. Participant demographics, exercise protocols, and outcomes varied widely. In the 10 eligible studies, a total of 99 comparisons were made between outdoor and indoor exercise; all 25 statistically significant comparisons favoured outdoor exercise. Interpretation of findings was hindered by an overall high risk of bias, unclear reporting, and high outcome heterogeneity. There is limited evidence for added health or behaviour benefits of outdoor exercise versus indoor exercise. Rigorous randomized controlled trials are needed with larger samples and clear reporting.

Background: Physical activity, sedentary behaviour, and sleep are three behaviours which occupy the 24-h cycle and interact to influence a multitude of health outcomes. Different terms are currently used to describe these behaviours collectively (e.g., movement behaviours or physical behaviours ). The lack of clear and consistent terminology makes it hard to compare, interpret, and build on research findings. As a first step towards developing consensus on what terminology to use for discussing the 24-h cycle of physical activity, sedentary behaviour, and sleep, we conducted a scoping review to identify the breadth of terminology used to describe this phenomenon. Methods: All searches occurred between September 18th – 20th 2024. We searched nine databases: Medline, EMBASE, CINAHL, PsycInfo, Web of Science, Scopus, ERIC, Education Source, and Compendex from inception to September 18th 2024. The Journal of Activity, Sedentary and Sleep Behaviors and the International Network of Time-Use Epidemiologists (INTUE) publication lists were manually searched on September 19th – 20th 2024. Peer-reviewed articles were included if they 1) were published in English, Spanish, Portuguese, French, Chinese, Korean, or Japanese; 2) focused on humans; and 3) describe physical activity, sedentary behaviour, and sleep in an integrated manner. We identified different terminologies used for collectively discussing physical activity, sedentary behaviour, and sleep across the 24-h cycle. Results: Our search identified 10,749 articles of which 979 articles met our inclusion criteria. Across all articles, 199 different terms were used to describe physical activity, sedentary behaviour, and sleep collectively. The term movement behaviours was used in 673 articles, 24-h movement behaviours was used in 457 articles, physical behaviours was used in 58 articles, 24-h activity cycle was used in 36 articles, and time-use behaviours was used in 31 articles. Conclusions: The two most popular terms for describing the collective interaction of physical activity, sedentary behaviour, and sleep are movement behaviours and 24-h movement behaviours . However, there is not yet an internationally recognized and agreed-upon term for holistically describing the 24-h cycle of physical activity, sedentary behaviour, and sleep. Developing a homogeneous and widely accepted set of terminology and definitions is thus critical if we hope to ensure clarity, enhance reproducibility, and enable the translation of future research into coherent guidelines, policies, and practices for these behaviours.

Background: Evidence from randomized controlled trials (RCTs) shows that aerobic exercise (AE) can benefit cognitive function among older adults with mild cognitive impairment (MCI). Growing research suggests that outdoor, natural (i.e., “green”) environments, compared with indoor or built environments, may augment the health benefits of exercise. However, the potential cognitive benefits of green exercise are unclear. We compared the effects of AE performed in an outdoor, green environment (O‐Ex) versus indoor AE (I‐Ex) on executive functions among older adults with MCI.Methods: A two‐arm parallel, single‐blinded, 12‐week proof‐of‐concept RCT. 72 community‐dwelling adults aged 65‐80 years with MCI were randomized (1:1) to either O‐Ex (n = 36) or I‐Ex (n = 36). Each arm involved two group‐based training sessions per week. Each session involved 10 min warm‐up, 40 min moderate‐intensity AE (progressing from 45%–75% of heart rate reserve), and 10 min cool‐down. We monitored exercise intensity using heart rate monitors and Borg’s 20‐point Rating of Perceived Exertion. AE consisted of outdoor walking in an urban forest (O‐Ex) or indoor treadmill walking or stationary cycling (I‐Ex). We measured working memory using the National Institutes of Health Toolbox (NIHTB) List Sorting Test and the Verbal Digits Forward and Backward Test. We measured set shifting and response inhibition using the NIHTB Dimensional Change Card Sort Test and Flanker Test, respectively. We performed a complete case analysis using a one‐way analysis of covariance to compare groupwise changes in executive functions (NIHTB corrected T‐score), with baseline outcome score and baseline Montreal Cognitive Assessment (MoCA) score as covariates. Overall alpha was ≤0.05.Results: Mean baseline MoCA score was 22.36 (SD = 2.55). Mean age was 74.08 years (SD = 3.92). There were 26 males and 46 females. The attrition rate was 12.5% (O‐Ex = 5; I‐Ex = 4). At 12 weeks, after adjusting for baseline outcome and baseline MoCA scores, O‐Ex had significantly better scores than I‐Ex for set shifting (estimated mean difference: 7.46; 95% CI: [2.69, 12.23]; p = 0.003) and response inhibition (estimated mean difference: 3.81; 95% CI: [0.61, 7.01]; p = 0.021), but not for working memory.Conclusions: Aerobic exercise performed outdoors in nature, compared with indoor aerobic exercise, may provide greater cognitive benefits among older adults with MCI.