Amidst strong efforts to promote the therapeutic benefits of physical activity for reducing depression and anxiety in clinical populations, little focus has been directed towards the mental health benefits of activity for non-clinical populations. The objective of this meta-meta-analysis was to systematically aggregate and quantify high-quality meta-analytic findings of the effects of physical activity on depression and anxiety for non-clinical populations. A systematic search identified eight meta-analytic outcomes of randomised trials that investigated the effects of physical activity on depression or anxiety. The subsequent meta-meta-analyses were based on a total of 92 studies with 4310 participants for the effect of physical activity on depression and 306 study effects with 10,755 participants for the effect of physical activity on anxiety. Physical activity reduced depression by a medium effect [standardised mean difference (SMD) = −0.50; 95% CI: −0.93 to −0.06] and anxiety by a small effect (SMD = −0.38; 95% CI: −0.66 to −0.11). Neither effect showed significant heterogeneity across meta-analyses. These findings represent a comprehensive body of high-quality evidence that physical activity reduces depression and anxiety in non-clinical populations.

The number of commercial apps to improve health behaviours in children is growing rapidly. While this provides opportunities for promoting health, the content and quality of apps targeting children and adolescents is largely unexplored. This review systematically evaluated the content and quality of apps to improve diet, physical activity and sedentary behaviour in children and adolescents, and examined relationships of app quality ratings with number of app features and behaviour change techniques (BCTs) used. Systematic literature searches were conducted in iTunes and Google Play stores between May–November 2016. Apps were included if they targeted children or adolescents, focused on improving diet, physical activity and/or sedentary behaviour, had a user rating of at least 4+ based on at least 20 ratings, and were available in English. App inclusion, downloading and user-testing for quality assessment and content analysis were conducted independently by two reviewers. Spearman correlations were used to examine relationships between app quality, and number of technical app features and BCTs included. Twenty-five apps were included targeting diet (n = 12), physical activity (n = 18) and sedentary behaviour (n = 7). On a 5-point Mobile App Rating Scale (MARS), overall app quality was moderate (total MARS score: 3.6). Functionality was the highest scoring domain (mean: 4.1, SD: 0.6), followed by aesthetics (mean: 3.8, SD: 0.8), and lower scoring for engagement (mean: 3.6, SD: 0.7) and information quality (mean: 2.8, SD: 0.8). On average, 6 BCTs were identified per app (range: 1–14); the most frequently used BCTs were providing ‘instructions’ (n = 19), ‘general encouragement’ (n = 18), ‘contingent rewards’ (n = 17), and ‘feedback on performance’ (n = 13). App quality ratings correlated positively with numbers of technical app features (rho = 0.42, p < 0.05) and BCTs included (rho = 0.54, p < 0.01). Popular commercial apps to improve diet, physical activity and sedentary behaviour in children and adolescents had moderate quality overall, scored higher in terms of functionality. Most apps incorporated some BCTs and higher quality apps included more app features and BCTs. Future app development should identify factors that promote users’ app engagement, be tailored to specific population groups, and be informed by health behaviour theories.

Physical activity theories have almost exclusively focused on conscious regulatory processes such as plans, beliefs, and expected value. The aim of this review was to aggregate the burgeoning evidence showing that physical activity is also partially determined by non-conscious processes (e.g., habits, automatic associations, priming effects). A systematic search was conducted and study characteristics, design, measures, effect size of the principle summary measures, and main conclusions of 52 studies were extracted by two independent coders. The findings support that habitual regulatory processes measured via self-report are directly associated with physical activity beyond conscious processes, and that there is likely interdependency between habit strength and intentions. Response latency measures of automatic associations with physical activity were widely disparate, precluding conclusions about specific effects. A small body of evidence demonstrated a variety of priming effects on physical activity. Overall, it is evident that physical activity is partially regulated by non-conscious processes, but there remain many unanswered questions for this area of research. Future research should refine the conceptualisation and measurement of non-conscious regulatory processes and determine how to harness them to promote physical activity.

As a result of recent calls to attend to the implicit processes that regulate health behaviors, the study of implicit attitudes and physical activity behavior has grown rapidly in the past decade. The aim of this study was to summarize existing evidence on the extent to which implicit attitudes toward physical activity are associated with physical activity behavior. A systematic literature review was performed to retrieve studies reporting both a measure of implicit attitudes and physical activity. For the meta-analysis, effect size (Pearson’s r) were extracted from eligible studies or retrieved from authors. A total of 26 independent studies, and 55 effect sizes, were eligible. There was a small, significant, and positive correlation between implicit attitudes and physical activity, a finding replicated across multiple meta-analytical strategies with sensitivity analyses applied. This association was not significantly moderated by study design or objective, participants’ age or other characteristics, or measures of implicit attitudes or physical activity. This meta-analysis provides evidence that implicit attitudes toward physical activity are positively associated with physical activity in adults to a small degree.

Advances in understanding how habit forms can help people change their behaviour in ways that make them happier and healthier. Making behaviour habitual, such that people automatically act in associated contexts due to learned context-response associations, offers a mechanism for maintaining new, desirable behaviours even when conscious motivation wanes. This has prompted interest in understanding how habit forms in the real world. To reliably inform intervention design, habit formation studies must be conceptually and methodologically sound. This paper proposes methodological criteria for studies tracking real-world habit formation, or potential moderators of the effect of repetition on formation. A narrative review of habit theory was undertaken to extract essential and desirable criteria for modelling how habit forms in naturalistic settings, and factors that influence the relationship between repetition and formation. Next, a methodological review identified exemplary real-world habit formation studies according to these criteria. Fourteen methodological criteria, capturing study design (four criteria), measurement (six criteria), and analysis and interpretation (four criteria), were derived from the narrative review. Five extant studies were found to meet our criteria. Adherence to these criteria should increase the likelihood that studies will offer revealing conclusions about how habits develop in real-world settings.

Habit change is often seen as key to successful long‐term behaviour change. Making ‘good’ behaviours habitual—that is, ensuring a behaviour is prompted automatically on exposure to situational cues, based on cue‐response associations learnt through context‐consistent repetition—is portrayed as a mechanism for sustaining such behaviours over time. Conversely, disrupting ‘bad’ habits is expected to terminate longstanding unwanted actions. Yet, some commentators have suggested that the role of habit in real‐world behaviour and behaviour change has been overstated. Such critiques highlight a gap between habit theory and the reality of human behaviour ‘in the wild’. This state‐of‐the‐field review aims to narrow this gap. Building on a core distinction between habit and habitual behaviour , our review seeks to offer interpretations of habit theory and evidence that will better manage intervention designers' expectations regarding how modifying habit can realistically be expected to promote behaviour change. We emphasise that habit is just one potential influence on behaviour at any given moment, and highlight instances in which habit may dominate over intention, and in which intention may dominate over habit, in determining behaviour frequency. We suggest that, while it may assist behaviour maintenance, habit formation may be neither necessary nor sufficient to sustain real‐world behaviour change. We draw attention to the various ways in which habit may be ‘broken’ (i.e., disrupted), and discern the implications of each habit disruption mechanism for long‐term cessation of unwanted behaviours.