Both physical activity (PA) and nature exposure are associated with several youth health benefits. However, the health outcomes when being physically active in nature, called Green Exercise (GE), are less clear. Thus, the purpose of this systematic review was to provide an overview of the psychosocial and physiological outcomes of GE in children and adolescents and to outline future GE research directions. The PRISMA statement guided the review. Web of Science, PubMed, ERIC, and APA PsychNET were systematically searched in February 2019, including studies between 2000 and 2019. Fourteen of 1175 identified publications were included, which reported 15 different psychosocial and six different physiological outcomes, with some studies reporting more than one outcome. For 16 outcomes, studies reported either similar or no effects for both GE and comparison groups. For six outcomes, studies reported stronger effects for GE, for three outcomes, studies reported stronger effects in the comparison group. Evidence was rated as weak, using the EPHPP tool. Thus, GE does not have deleterious effects for children and adolescents compared to PA in other settings. GE might be beneficial; however, due to the study’s heterogeneity and quality, it is premature to make definite conclusions. Future research should build the quality of evidence for GE, use more rigorous research designs, and investigate the underlying effects and mechanisms of GE.

Objective: The purposes of this paper were to (a) develop a new short, theory-driven, version of the physical activity enjoyment scale (PACES-S) using content analysis; and (b) subsequently to measure the psychometric properties (construct validity, internal consistency, test–retest reliability, and concurrent validity) of the PACES-S for adolescents. Methods: Six experts used a four-point Likert scale to assess the content validity of each of the 16 items of the physical activity enjoyment scale according to a provided definition of physical activity enjoyment. Based on the results, exploratory factor analysis was used to analyze survey data from a longitudinal study of 182 individuals (Measure 1 of Study 1: 15.75 ± 3.39 yrs; 56.6% boys, 43.4% girls), and confirmatory factor analysis (Measure 2 of Study 1: 15.69 ± 3.44 yrs; 56.3% boys, 43.7% girls) was used to analyze the survey data from a cross-sectional study of 3219 individuals (Study 2; 15.99 ± 3.10 yrs; 47.8% boys, 52.2% girls) to assess the construct validity of the new measure. To assess the reliability, test–retest reliability was assessed in Study 1 and internal consistency in Study 1 and 2. For the concurrent validity, correlations with self-reported and device-based physical activity behavior were assessed in both studies. Results: Four out of sixteen items were selected for PACES-S. Exploratory factor analysis and confirmatory factor analyses identified and supported its factorial validity (χ2 = 53.62, df = 2, p < 0.001; RMSEA = 0.073; CFI = 0.99; RFI = 0.96; NFI = 0.99; TLI = 0.96; IFI = 0.99). Results showed good test–retest reliability (r = 0.76) and internal consistency (a = 0.82 to 0.88). Regarding concurrent validity, the results showed positive correlations with a physical activity questionnaire (Study 1: r = 0.36), with a physical activity diary (Study 1: r = 0.44), and with accelerometer-recorded data (Study 1: r = 0.32; Study 2: r = 0.21). Conclusions: The results indicate that PACES-S is a reliable and valid instrument that may be particularly useful to measure physical activity enjoyment in large-scale studies. It shows comparable measurement properties as the long version of PACES.

Purpose: To explain physical activity behavior, social-cognitive theories were most commonly used in the past. Besides conscious processes, the approach of dual processes additionally incorporates non-conscious regulatory processes into physical activity behavior theories. Habits are one of various non-conscious variables that can influence behavior and thus play an important role in terms of behavior change. The aim of this review was to examine the relationship between habit strength and physical activity behavior in longitudinal studies.Methods: According to the PRISMA guidelines, a systematic search was conducted in three databases. Only peer-reviewed articles using a longitudinal study design were included. Both, habit and physical activity were measured at least once, and habit was related to physical activity behavior. Study quality was evaluated by assessment tools of the NHLBI.Results: Of 3.382 identified publications between 2016 and 2019, fifteen studies with different study designs were included. Most studies supported that positive correlations between habit and physical activity exist. Some positive direct and indirect effects of habit on physical activity were detected and only a minority of studies showed the influence of physical activity on habit strength. Studies differentiating between instigation and execution habit found positive correlations and revealed instigation habit as a stronger predictor of physical activity. The quality of studies was rated as reasonable using assessment tools of the NHLBI.Conclusion: This review revealed a bidirectional relationship between habit and physical activity. Whether habit predicts physical activity or vice versa is still unclear. The observation of habit influencing physical activity may be most appropriate in studies fostering physical activity maintenance while the influence of physical activity on habit may be reasonable in experimental studies with physical activity as intervention content to form a habit. Future investigations should differentiate between habit formation and physical activity maintenance studies depending on the research objective. Long-term study designs addressing the complexity of habitual behavior would be beneficial for establishing cue-behavior associations for the formation of habits. Furthermore, studies should differentiate between instigation and execution habit in order to investigate the influence of both variables on physical activity behavior independently.

Future-oriented emotions could influence our decisions in everyday life and help understand why some individuals are physically active whilst others are not. Current literature distinguishes between two future-oriented emotion constructs: anticipatory and anticipated emotions. While anticipatory emotions are currently experienced emotions about a future event, anticipated emotions refer to the emotions that a person is expected to experience when confronted with a future event. The main aims of the present study were (1) to identify and describe (a) categories of anticipatory emotions experienced before exercise, and (b) categories of anticipated emotions expected to be experienced during and after exercise, and (2) to develop a theoretical model of anticipated emotion categories. Sixteen participants (Mage = 26.03, SD = 6.66) were recruited for semi-structured interviews, and their statements were analyzed using principles of the Grounded Theory. In total, 13 different anticipatory and anticipated emotion categories were identified, such as enjoyment, anxiety, pride, self-anger, and relief. Anticipatory emotions seem to reflect the current affective valence of exercising and may be influenced by daily factors. With regards to anticipated emotions, the results show that regular exercisers anticipated also negative emotions such as anxiety, disappointment, and self-anger, and non-regular exercisers also anticipated positive emotions such as enjoyment, pride, and satisfaction. Therefore, future research should not only focus on the valence of future-oriented emotions, but should investigate the possible impact of specific anticipated emotions on exercise behavior. In addition, a theoretical model of anticipated emotion categories in exercise behavior derived from the interviews. The model outlines different categories of anticipated emotions based on appraisal processes. In conclusion, we assume that this developmental process of anticipated emotions may be embedded in a broader, cyclical process within the context of exercising.

Objectives: Habitually instigated exercise is thought to increase health behavior maintenance. Previous research has explored several aspects of habit formation. However, there is a lack of longitudinal research investigating affective determinants, especially post-exercise affective states. Therefore, the present study aimed to investigate (a) if behavior frequency will enhance automaticity, (b) if positive affect will enhance automaticity, and (c) if positive affect will moderate the relationship between behavior frequency and automaticity. Methods: 226 participants (64% females, mean age 24 years) who attended weekly sports and gym classes at two universities were followed for 13 weeks. Class attendance was documented on a weekly basis (behavior frequency) during the semester. Before, during and immediately after each class, participants filled in the Feeling Scale (affective valence). Furthermore, at the beginning of each class, they answered a question about their automaticity in arriving at the decision to attend the class (instigation habit). We used a two-level modeling approach to predict subsequent automaticity by the different constructs at the previous attendance. Results: The cumulative frequency of prior class attendance did not significantly enhance the automaticity of the decision to re-attend the class. There were significant effects of valence on automaticity on the between-subject level, i.e., a one-point higher mean valence score was associated with a 0.62 point increase in automaticity (p = 0.001). No moderation effects of affect on the association between behavior frequency and automaticity were observed. Conclusion: Behavior repetition, albeit not significant, and positive affective states at the end of an exercise class may be beneficial in building exercise instigation habits. Practitioners and researchers alike may thus want to emphasize the importance of behavior repetition and affective response for health behavior maintenance.