Applying Mixed-Effects Location Scale Modeling to Examine Within-Person Variability in Physical Activity Self-Efficacy

Abstract: Background: Physical activity self-efficacy is conceptualized as a construct that is changeable and responsive to contextual factors. The current study applied mixed-effects location scale modeling to examine within-person variability in physical activity self-efficacy among middle-aged and older adults (N = 14 adults, mean age = 59.4 years) who were attempting behavior change. Methods: An electronic diary was used to record self-reported self-efficacy and physical activity via Ecological Momentary Assessment (EMA) twice a day (2:00 pm and 9:00 pm). Data from weeks 1-6 were analyzed using a Mixed-Effects Location Scale Model in SAS PROC NLMIXED. Results: Participants differed from each other in the degree to which physical activity self-efficacy varied from day to day (p = .03). Within-person variation in self-efficacy was negatively related to levels of brisk walking each week (p = .002), and decreased over time (p = .03). Conclusions: Preliminary results suggest that fluctuations in self-efficacy may be as important for predicting short-term behavior as the overall or mean level of self-efficacy

Media use and obesity in adolescent females.

ObjectiveIn the context of growing public health concern with the obesity rates among children and adolescents, much attention has focused on the role of television as a contributor to the problem. Less attention has been devoted to interactive media (internet surfing and video games), despite the fact that these forms of entertainment are fast gaining in popularity among youth. This study investigated the relative associations of TV viewing and interactive media use with body fat and BMI, controlling for both physical activity participation and cardiovascular fitness.Research methods and proceduresFemale high-school adolescents (N = 194) were assessed for cardiovascular fitness (cycle ergometer), percent body fat (DXA), and BMI. Time spent in moderate, vigorous, and sedentary activities was assessed with a 3-day recall.ResultsMultivariate regression analysis showed that only interactive media use was associated with percentage body fat and BMI, and the relationship remained strong even after controlling for physical activity participation and cardiovascular fitness.DiscussionIt appears that, among this group of adolescent females, the association between interactive media use and obesity is not explained by a reduction in moderate or vigorous activity commensurate with media use

The acute relationships between affect, physical feeling states, and physical activity in daily life: A review of current evidence

Until recently, most studies investigating the acute relationships between affective and physical feeling states and physical activity were conducted in controlled laboratory settings, whose results might not translate well to everyday life. This review was among the first attempts to synthesize current evidence on the acute (e.g., within a few hours) relationships between affective and physical feeling states and physical activity from studies conducted in free-living, naturalistic settings in non-clinical populations. A systematic literature search yielded 14 eligible studies for review. Six studies tested the relationship between affective states and subsequent physical activity; findings from these studies suggest that positive affective states were positively associated with physical activity over the next few hours while negative affective states had no significant association. Twelve studies tested affective states after physical activity and yielded consistent evidence for physical activity predicting higher positive affect over the next few hours. Further, there was some evidence that physical activity was followed by a higher level of energetic feelings in the next few hours. The evidence for physical activity reducing negative affect in the next few hours was inconsistent and inconclusive. Future research in this area should consider recruiting more representative study participants, utilizing higher methodological standards for assessment (i.e., electronic devices combined with accelerometry), reporting patterns of missing data, and investigating pertinent moderators and mediators (e.g., social and physical context, intensity, psychological variables). Knowledge gained from this topic could offer valuable insights for promoting daily physical activity adoption and maintenance in non-clinical populations

Physical Activity and Physical Self-Concept among Sedentary Adolescent Females; An Intervention Study.

PROBLEM: Physical activity has been promoted as a means of enhancing self-concept, yet the evidence for this connection is far from compelling. In particular, experimental research investigating this association during adolescence, a period during which many youth struggle to maintain a positive self-image, is noticeably lacking. This study investigates the impact on self-concept of a 9-month physical activity intervention among sedentary adolescent females. METHOD: Female adolescents who were sedentary at baseline were assigned either to an exercise intervention or a comparison group as part of the controlled trial. The intervention was school-based, and assignment to groups was based on school attended. Intervention participants engaged in supervised activity 4 times per week and received didactic instruction promoting activity outside of school 1 day per week. Self-concept, physical activity participation, and cardiovascular fitness were assessed before, mid-way through, and after the 9-month intervention. RESULTS: The intervention had a significant positive impact on participation in vigorous activity and cardiovascular fitness. The intervention did not significantly influence any of the self-concept dimensions overall. There was, however, a three-way interaction such that there was an increase in global physical self-concept among those intervention participants who increased cardiovascular fitness. CONCLUSIONS: These findings indicate that a physical activity intervention among sedentary adolescent females enhanced global physical self-concept for a subset of intervention participants who manifested positive changes in fitness

Physical Activity and Physical Self-Concept among Sedentary Adolescent Females; An Intervention Study.

PROBLEM: Physical activity has been promoted as a means of enhancing self-concept, yet the evidence for this connection is far from compelling. In particular, experimental research investigating this association during adolescence, a period during which many youth struggle to maintain a positive self-image, is noticeably lacking. This study investigates the impact on self-concept of a 9-month physical activity intervention among sedentary adolescent females. METHOD: Female adolescents who were sedentary at baseline were assigned either to an exercise intervention or a comparison group as part of the controlled trial. The intervention was school-based, and assignment to groups was based on school attended. Intervention participants engaged in supervised activity 4 times per week and received didactic instruction promoting activity outside of school 1 day per week. Self-concept, physical activity participation, and cardiovascular fitness were assessed before, mid-way through, and after the 9-month intervention. RESULTS: The intervention had a significant positive impact on participation in vigorous activity and cardiovascular fitness. The intervention did not significantly influence any of the self-concept dimensions overall. There was, however, a three-way interaction such that there was an increase in global physical self-concept among those intervention participants who increased cardiovascular fitness. CONCLUSIONS: These findings indicate that a physical activity intervention among sedentary adolescent females enhanced global physical self-concept for a subset of intervention participants who manifested positive changes in fitness