Background The social cognitive framework is a long-standing framework within physical activity promotion literature to explain and predict movement-related behaviors. However, applications of the social cognitive framework to explain and predict movement-related behaviors have typically examined the relationships between determinants and behavior across macrotimescales (eg, weeks and months). There is more recent evidence suggesting that movement-related behaviors and their social cognitive determinants (eg, self-efficacy and intentions) change across microtimescales (eg, hours and days). Therefore, efforts have been devoted to examining the relationship between social cognitive determinants and movement-related behaviors across microtimescales. Ecological momentary assessment (EMA) is a growing methodology that can capture movement-related behaviors and social cognitive determinants as they change across microtimescales. Objective The objective of this systematic review was to summarize evidence from EMA studies examining associations between social cognitive determinants and movement-related behaviors (ie, physical activity and sedentary behavior). Methods Studies were included if they quantitatively tested such an association at the momentary or day level and excluded if they were an active intervention. Using keyword searches, articles were identified across the PubMed, SPORTDiscus, and PsycINFO databases. Articles were first assessed through abstract and title screening followed by full-text review. Each article was screened independently by 2 reviewers. For eligible articles, data regarding study design, associations between social cognitive determinants and movement-related behaviors, and study quality (ie, Methodological Quality Questionnaire and Checklist for Reporting Ecological Momentary Assessment Studies) were extracted. At least 4 articles were required to draw a conclusion regarding the overall associations between a social cognitive determinant and movement-related behavior. For the social cognitive determinants in which a conclusion regarding an overall association could be drawn, 60% of the articles needed to document a similar association (ie, positive, negative, or null) to conclude that the association existed in a particular direction. Results A total of 24 articles including 1891 participants were eligible for the review. At the day level, intentions and self-efficacy were positively associated with physical activity. No other associations could be determined because of conflicting findings or the small number of studies investigating associations. Conclusions Future research would benefit from validating EMA assessments of social cognitive determinants and systematically investigating associations across different operationalizations of key constructs. Despite the only recent emergence of EMA to understand social cognitive determinants of movement-related behaviors, the findings indicate that daily intentions and self-efficacy play an important role in regulating physical activity in everyday life. Trial Registration PROSPERO CRD42022328500; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=328500

BACKGROUND Social cognitive frameworks have been a longstanding framework within literature to explain and predict movement-related behaviors. These behaviors have been researched greatly in macro-timescales, but daily levels of movement-related behaviors can differ and be influenced by within-day social cognitive determinants (e.g., self-efficacy, intentions). Ecological Momentary Assess-ment (EMA) is a growing methodology that can capture movement-related behaviors and social cognitive determinants as they change in micro-timescales. OBJECTIVE The objective of this systematic review was to summarize evidence from Ecological Momentary Assessment (EMA) studies examining associations between social cognitive determinants and movement-related behaviors (i.e., physical activity (PA), sedentary behavior (SB)). METHODS Articles were included if they quantitatively tested such an association at the momentary- or day-level and excluded if they were an active intervention. Articles were identified across PubMed, SPORTDiscus, and PsychINFO databases. Each article was screened independently by two re-viewers. Twenty-four articles (N = 1,891 participants) were eligible from which data regarding participants, study design, associations between social cognitive determinants and movement-related behaviors and article quality (i.e., Methodological Quality Questionnaire, Checklist for Reporting EMA Studies) were extracted. At least 60% of articles needed to document similar asso-ciations to conclude an overall association existed. RESULTS At the day-level, intentions and self-efficacy were positively associated with PA. No other associa-tions could be determined due to conflicting findings or too few articles investigating associations. CONCLUSIONS Future research would benefit from validating EMA assessments of social cognitive determinants and systematically investigating associations across different operationalizations of key constructs. Despite the recent emergence of EMA to understand social cognitive determinants of movement-related behaviors, findings indicate that daily intentions and self-efficacy play an important role in regulating PA in everyday life. CLINICALTRIAL This review was registered through Prospero #CRD42022328500.