Mediators Of Physical Activity Research Articles

Exploring the Mediating Role of Physical Activity in the Relationship between Green Space Exposure and Well-being: Results from the AUGS Survey

Although previous studies have shown that exposure to nature has a positive impact on physical and mental health, the factors that produce such benefits are still not well established, especially in high- and middle-income countries. In the present study, we implemented a mediation approach between green space exposure and psychological distress, body fat percentage and well-being index in Tirana (Albania), through the mediation of physical activity. The significant direct effects of green space on body fat percentage index (BFPI), psychological distress index (PDI) and well-being index, together with the relatively smaller mediating role of physical activity, offer insightful implications for the design and prioritization of urban green spaces. The differential impact on health outcomes suggests a complex association that is not only mediated by physical activity, but also offers clear benefits by reducing psychological distress (as indicated by PDI scores) and significantly improving overall well-being. This dichotomy highlights the multifaceted role of green spaces in public health, requiring a broad lens that goes beyond physical health metrics to include mental health and subjective well-being. Our findings also confirm the intrinsic value of green spaces in improving well-being and reducing psychological distress, independent of the physical activities they may promote.

Association of frailty with workplace social activity, physical activity, and well-being among older employees: a moderated mediation in two income-variant samples

BackgroundResearch suggests that frailty is associated with lower physical activity and well-being in old age, but social activities at work may facilitate physical activity and its positive effect on well-being among older employees with frailty. This study, therefore, ascertained whether there is a moderated mediation of the association of frailty, Workplace Social Activity (WSA), and well-being by Physical Activity (PA).MethodsThe study adopted a cross-sectional design with relevant sensitivity analyses for confounding. The participants were within two Ghanaian samples with different income levels (low-income, n = 897, and higher income, n = 530). The minimum samples were calculated, and the statistical models were tested with Haye’s Process Model through structural equation modelling.ResultsFrailty was negatively associated with PA, and this relationship was moderated by WSA in both samples. Higher frailty was directly and indirectly associated with lower well-being in the higher-income sample but only indirectly associated with lower well-being in the low-income sample. The mediation of PA in the frailty-well-being relationship is partial in the higher-income sample but complete in the low-income sample. There was evidence of moderated mediation in both samples.ConclusionWSA may reduce the strength of the negative association of frailty with PA and well-being among older employees in both samples. Workplace interventions aimed at enhancing WSA may encourage PA and enhance well-being among older employees with frailty.

Is physical activity associated with a higher degree of wisdom? Cross-sectional study with high school students

The aim of this study was to verify the association between the degree of wisdom and the level of leisure-time physical activity (PA) of students from a federal public school in southern Brazil. Observational cross-sectional study with 462 young people of both sexes between 15 and 18 years old. Data collection was performed using a self-administered questionnaire on the REDCap platform. The independent variable was the “level of leisure PA” (inactive, insufficiently active, and physically active) and the outcome was the “degree of wisdom” evaluated through a validated questionnaire (SD-WISE7). There was a linear trend towards an increase in the wisdom score according to the level of PA. This trend and significant association continued in the adjusted analysis, with active students averaging 1.84 points more in the wisdom score compared to inactive students. In conclusion, the wisest young people are also the most physically active young people. In view of the potential beneficial effects, current studies may consider wisdom as a possible mediator of PA with health outcomes.

Heart rate variability is reduced in COVID-19 survivors and associated with physical activity and fatigue.

Reduced heart rate variability (HRV) and fatigue are common after COVID-19 infection and both are potentially influenced by physical activity (PA). We compared resting HRV, PA from accelerometers and questionnaires, and self-reported fatigue in 41 COVID-19 survivors (~8 months postinfection, 38 ± 17 years) with 41 matched controls. Differences in HRV were observed on acceleration capacity (p = 0.041), deceleration capacity (p = 0.032), high-frequency peak frequency (p = 0.019), absolute low-frequency power (p = 0.042), relative very low-frequency power (p = 0.012), SD2 (from Poincare plot; p = 0.047), and DFA2 (slope of long-term detrended fluctuation analysis; p = 0.004). Fatigue was greater in COVID-19 survivors (p < 0.001) with no differences in PA. Moderate-vigorous physical activity (MVPA) (Standardized Beta = -0.427, p = 0.003) and steps per day (Standardized Beta = -0.402, p = 0.007) were associated with DFA2 in COVID-19 survivors after controlling for age, sex, and body fat percentage. Fatigue was correlated to less MVPA (Spearman's rho = 0.342, p = 0.031) and fewer steps per day (rho = 0.329, p = 0.038) in COVID-19 survivors, and was indirectly linked to HRV through these PA mediators (Estimate = -0.20; p = 0.040). We present a model showing the complex relations between HRV, PA, and fatigue that provides the foundation for strategies to improve outcomes and rehabilitation after COVID-19 infection.

Life satisfaction and parental support among secondary school students in Urumqi: the mediation of physical activity.

This study is aimed to analyze the relationship between parental support, physical activity and life satisfaction among secondary school students in Urumqi city, and also to explore the mediating role of physical activity in the relationship between life satisfaction and parental support among secondary school students. A questionnaire survey was conducted from December 2021 to January 2022, using a stratified whole-group random sampling method among 2,474 secondary school students aged 11-18 years in Urumqi city, including a general demographic questionnaire, a Chinese version of the Child and Adolescent Physical Activity Questionnaire, Chinese version of the Child and Adolescent Parental Support Scale, and the Multidimensional Student Life Satisfaction Scale. The Bootstrap mediating effect test was used to test the effect relationship between the variables, and Amos was adopted to analyze the mediating effect of physical activity between secondary school students' life satisfaction and parental support. Secondary school students scored (33.22 ± 5.68) on life satisfaction, (2.11 ± 0.64) on physical activity, (24.85 ± 4.31) on the mother's roll and (24.73 ± 4.40) on the father's roll. Maternal support was a significant direct predictor of life satisfaction (β=0.303, t=11.893, P<0.01). Maternal support was a positive predictor of physical activity (β=0.027, t = 9.332, P<0.01). And the physical activity was a positive predictor of life satisfaction (β=1.362, t = 7.665, P < 0.01). Paternal support was a significant direct predictor of life satisfaction (β=0.334, t = 13.448, P < 0.01). Paternal support was a positive predictor of physical activity (β=0.030, t = 10.665, P < 0.01). Physical activity was a positive predictor of life satisfaction (β=1.264, t = 7.119, P<0.01). Physical activity had a mediating effect between life satisfaction and parental support (effect values: 11.88% in maternal support and 11.38% in paternal support, respectively). The supportive parental environment of secondary school students in Urumqi can directly influence their life satisfaction and also indirectly influence their life satisfaction by enhancing their physical activity level, and parental support for physical activity of secondary school students should be enhanced to promote their life satisfaction level.

Do Physical Fitness and Executive Function Mediate the Relationship between Physical Activity and Academic Achievement? An Examination Using Structural Equation Modelling.

Background: Physical activity health benefits are widely known. However, the association between physical activity, physical fitness, executive function, and academic performance need further investigation. Additionally, one of the literature gaps reveals scarce and mixed findings on what mediators of physical activity may affect academic achievement. Purpose: This investigation aims to provide knowledge about the mediation role of physical fitness and executive function in the association of physical activity with academic achievement in a cohort of Spanish schoolchildren using a structural equation modelling approach. Methods: The data for this cross-sectional study were collected from a convenience sample of children from Spain (Balearic Islands) aged between 9 and 13 years. Physical activity levels were self-reported with the Physical Activity Questionnaire for Children; physical fitness was assessed using the International Fitness Scale; executive function was assessed with the Trail Making Test, and children’s achievements were collected from the school records. Structural equation modelling was used to explore the relationship between physical activity, physical fitness, executive function, and academic achievement. Findings: Statistically significant positive direct associations were observed between physical activity and physical fitness (β = 0.46, 95% CI [0.29, 0.64]), physical fitness and executive function (β = 0.28, 95% CI [0.04, 0.52]), and executive function and academic achievement (β = 0.46, 95% CI [0.28, 0.65]), while adjusting for the confounding effects of sex and body mass index. Furthermore, indirect associations were observed between physical activity and executive function mediated by physical fitness (β = 0.13, bias-corrected 95% CI [0.02, 0.31]) and between physical fitness and academic achievement through executive function (β = 0.13, bias-corrected 95% CI [0.03, 0.32]). Conclusions: This investigation adds to the literature with evidence supporting the idea that regular PA leads to improvements in physical fitness and may support cognitive skills and academic performance in children.

Children of Smoking and Non-Smoking Households' Perceptions of Physical Activity, Cardiorespiratory Fitness, and Exercise.

Previous research has shown secondhand tobacco smoke to be detrimental to children’s health. This qualitative study aimed to explore children from low socioeconomic status (SES) families and their reasons for being physically active, attitudes towards physical activity (PA), fitness and exercise, perceived barriers and facilitators to PA, self-perceptions of fitness and physical ability, and how these differ for children from smoking and non-smoking households. A total of 38 children (9–11 years; 50% female; 42% smoking households) from the deprived areas of North West England participated in focus groups (n = 8), which were analysed by utilizing thematic analysis. The findings support hypothesised mediators of PA in children including self-efficacy, enjoyment, perceived benefit, and social support. Fewer than a quarter of all children were aware of the PA guidelines with varying explanations, while the majority of children perceived their own fitness to be high. Variances also emerged between important barriers (e.g., sedentary behaviour and environmental factors) and facilitators (e.g., psychological factors and PA opportunity) for children from smoking and non-smoking households. This unique study provided a voice to children from low SES and smoking households and these child perspectives could be used to create relevant and effective strategies for interventions to improve PA, fitness, and health.

Mediators of physical activity between standard exercise and exercise video games.

Exercise video games (EVGs) may offer an attractive, sustainable alternative or supplement to traditional modes of exercise. Understanding the psychosocial factors that influence the appeal of EVGs is important for improving the efficacy of video games as a method of promoting the uptake and long-term maintenance of physical activity. This study examined changes in psychosocial constructs from self-determination theory and self-efficacy theory as mediators of intervention efficacy among 189 healthy, sedentary adults randomized to 12-week programs of either EVGs or standard exercise (e.g., treadmill walking, stationary cycling) followed by 6 months of follow-up. The EVG group engaged in significantly more weekly minutes of moderate to vigorous physical activity (MVPA) at the end of treatment compared with the standard exercise group. Univariate and multivariate mediational models were used to examine theoretically derived psychosocial constructs as potential mediators of differential intervention effects. Univariate mediational models suggest a significant indirect effect of treatment on MVPA outcomes through enjoyment, self-efficacy, stress management, depressive symptoms, and positive engagement (p < .05). Multiple mediational analyses confirm all the univariate results (p < .05), with the exception of enjoyment. Differences in the efficacy of EVG versus standard exercise interventions were mediated by several psychosocial constructs, suggesting that qualities specific to game play may enhance adherence to physical activity both in and outside of the laboratory environment. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Abstract 026: Early Life Exposure to Green Areas and Diabetes Risk, an Assessment From Infancy to Early Teens

Background: Increasing empirical evidence suggests that exposure to nature (natural vegetation, or “greenness”) influences health. Studies have shown that greenness is related to lower diabetes risk possibly through mediation of physical activity, harmful environmental exposures, or mental health. However, to our knowledge, no previous study has reported on associations between greenness and insulin resistance in children. We hypothesize that children are more sensitive to environmental exposures particularly during critical windows of susceptibility. Our research aims to evaluate the early life association between greenness and insulin resistance and assess vulnerable life-periods in which individuals are more susceptible to their surroundings. Methods: We use data from Project Viva, a longitudinal cohort study designed to study prenatal factors, pregnancy outcomes, and child health. From 1999 to 2002, we recruited pregnant women from a multispecialty group practice in Massachusetts. Of the 1,036 who attended the early teen research visit, we considered 460 participants who provided fasting blood and had complete data for all covariates and exposure at infancy (less than one year), early childhood (median age 3.3 years), mid-childhood (median age 7.7 years) and early teens (median age 13.2). We defined greenness exposure surrounding each participant’s address using 30m resolution Landsat satellite imagery [Normalized Difference Vegetation Index] at infancy (under one year of age), early childhood, mid-childhood, and early teens. Our main outcome measurement was the homeostatic model assessment to estimate insulin resistance (HOMA-IR) at the early teen visit. Results: In models adjusted for age, race, sex, mother’s education, father’s education, household income and median household income from the census tract at delivery, living in the highest quintile of greenness in the 90-m area at the early teen visit was associated with 0.65 lower HOMA-IR (95%CI: -1.52, -0.40) than those in the lowest quintile. The observed association between higher greenness exposure and lower HOMA-IR in early teens was consistent for the 270-m area, although slightly attenuated, and no longer significant for the 1230-m area (mean HOMA-IR was 3.06, SD=2.08). We found no associations of exposure to greenness in the 90-m, 270-m or 1230-m areas around participants’ home at infancy, early childhood, or mid-childhood with early teenage HOMA-IR. Conclusions: Higher levels of green vegetation, especially closer to the home, at the early teen visit were associated with lower insulin resistance at the same time period. Early exposure to green space during infancy, early childhood and mid-childhood was not associated with HOMA-IR as an early teenager. Early childhood longitudinal studies including geographic contextual factors across diverse populations are needed to confirm or refute these findings.

Anti-Inflammatory Properties of Irisin, Mediator of Physical Activity, Are Connected with TLR4/MyD88 Signaling Pathway Activation.

Irisin, an adipomiokine known as a mediator of physical activity, induces the browning of adipose tissue and it has potentially protective properties in the development of obesity-related states, such as insulin resistance, arteriosclerosis, and type 2 diabetes. Despite numerous studies conducted on this factor, still little is known about its impact on the functioning of immunocompetent cells, but its potential anti-inflammatory properties were previously suggested. In the current study we investigated the role of irisin (0–100 nM) in the downstream pathway activation of Toll-like receptor 4 (TLR4) in RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS; 100 ng/mL). The results have shown that irisin in high concentrations (50, 100 nM) significantly decreased the TLR4 and MyD88 protein levels, as well as the phosphorylation of nuclear factor-κB (NF-κB), consequently leading to the reduction in the release of crucial pro-inflammatory cytokines. The above was confirmed for interleukin 1β (IL-1β), tumor necrosis factor α (TNFα), interleukin 6 (IL-6), keratinocyte chemoattractant (KC), monocyte chemotactic protein 1 (MCP-1), as well as for high mobility group box 1 (HMGB1). Moreover, our results indicate that this effect is connected with irisin’s impact on the phosphorylation of mitogen-activated protein kinases (MAPKs), where a significant reduction in p-JNK and p-ERK but not p-p38 was observed. In conclusion, these data suggest that irisin has potentially anti-inflammatory properties connected with the downregulation of downstream pathways of TLR4/MyD88.

What explains the socioeconomic status gap in activity? Educational differences in determinants of physical activity and screentime

BackgroundDesigning evidence-based interventions to address socioeconomic disparities in health and health behaviours requires a better understanding of the specific explanatory mechanisms. We aimed to investigate a comprehensive range of potential theoretical mediators of physical activity (PA) and screen time in different socioeconomic status (SES) groups: a high SES group of high school students, and a low SES group of vocational school students. The COM-B system, including the Theoretical Domains Framework (TDF), was used as a heuristic framework to synthesise different theoretical determinants in this exploratory study.MethodsFinnish vocational and high school students (N = 659) aged 16–19, responded to a survey assessing psychological, social and environmental determinants of activity (PA and screen time). These determinants are mappable into the COM-B domains: capability, opportunity and motivation. The outcome measures were validated self-report measures for PA and screen time. The statistical analyses included a bootstrapping-based mediation procedure.ResultsRegarding PA, there were SES differences in all of the COM-B domains. For example, vocational school students reported using less self-monitoring of PA, weaker injunctive norms to engage in regular PA, and fewer intentions than high school students. Mediation analyses identified potential mediators of the SES-PA relationship in all of three domains: The most important candidates included self-monitoring (CI95 for b: 0.19–0.47), identity (0.04–0.25) and material resources available (0.01–0.16). However, SES was not related to most determinants of screentime, where there were mainly gender differences. Most determinants were similarly related with both behaviours in both SES groups, indicating no major moderation effect of SES on these relationships.ConclusionsThis study revealed that already in the first years of educational differentiation, levels of key PA determinants differ, contributing to socioeconomic differences in PA. The analyses identified the strongest mediators of the SES-PA association, but additional investigation utilising longitudinal and experimental designs are needed. This study demonstrates the usefulness of combining constructs from various theoretical approaches to better understand the role of distinct mechanisms that underpin socioeconomic health behaviour disparities.

Antecedents and mediators of physical activity in endometrial cancer survivors: Increasing physical activity through steps to health.

Research has shown that physical activity (PA) has a positive effect on cancer survivors, including improving quality of life, improving physical fitness, and decreasing risk for cancer recurrence in some cancer types. Theory-based intervention approaches have identified self-efficacy as a potential mediator of PA intervention. This study examines the temporal relationships at 4 time points (T1-T4) between several social-cognitive theory constructs and PA among a group of endometrial cancer survivors receiving PA intervention. A sample of 98 sedentary women who were at least 6 months posttreatment for endometrial cancer were given interventions to increase their PA. We tested whether modeling, physiological somatic sensations, and social support at previous time points predicted self-efficacy at later time points, which in turn would predict PA at later time points. Results indicated that, as physiological somatic sensations at T2 decreased, self-efficacy at T3 increased, which led to an increase in PA at T4. This suggests that self-efficacy is a significant mediator between physiological somatic sensations and PA. Exploratory follow-up models suggest that model fit can be improved with the addition of contemporaneous effects between self-efficacy and PA at T3 and T4, changing the timing of the mediational relationships. Physiological somatic sensations appear to be an important construct to target to increase PA in this population. Self-efficacy appeared to mediate the relationship between physiological somatic sensations and PA, but the timing of this relationship requires further study. (PsycINFO Database Record

Effectiveness of a school-community linked program on physical activity levels and health-related quality of life for adolescent girls

BackgroundThis study evaluated the effectiveness of a school-community program on Health-Related Quality of Life (HRQoL; the primary outcome), physical activity (PA), and potential mediators of PA among adolescent girls living in low-socioeconomic rural/regional settings.MethodThe study was a cluster-randomized controlled trial. Twelve communities with the requisite sports clubs and facilities were paired according to relevant criteria; one of each pair was randomly assigned to the intervention or control condition. Eight schools per condition were randomly selected from these communities and the intervention was conducted over one school year (2011). Female students in grades 7–9 in intervention schools participated in two 6-session PA units – a sport unit (football or tennis) and a recreational unit (leisure centre-based). These were incorporated into physical education (PE) curriculum and linked to PA opportunities for participation outside school. Students were surveyed at baseline and endpoint, self-reporting impact on primary and secondary outcome measures (HRQoL, PA) and PA mediators (e.g. self-efficacy). Linear mixed models for two-group (intervention, control) and three-group (completers, non-completers, control) analyses were conducted with baseline value, age and BMI as covariates, group as a fixed effect and school as random cluster effect.ResultsParticipants completing baseline and endpoint measures included: 358 intervention (baseline response rate 33.7%, retention rate 61.3%) and 256 control (14.1% and 84.0%). Adjustment for age and BMI made no substantive difference to outcomes, and there were no cluster effects. For HRQoL, after adjustment for baseline scores, the intervention group showed significantly higher scores on all three PedsQL scores (physical functioning: M ± SE = 83.9 ± 0.7, p = .005; psychosocial: 79.9 ± 0.8, p = .001; total score: 81.3 ± 0.7, p = .001) than the control group (80.9 ± 0.8; 76.1 ± 0.9 and 77.8 ± 0.8). The three-group analysis found intervention non-completers had significantly higher PedsQL scores (84.0 ± 0.8, p = .021; 80.4 ± 0.9, p = .003; 81.7 ± 0.8, p = .002;) than controls (80.9 ± 0.8, 76.1 ± 0.9 and 77.8 ± 0.8). There were no significant differences for any PA measure. Intervention completers had significantly higher scores than non-completers and controls for some mediator variables (e.g. self-efficacy, behavioural control).ConclusionPositive outcomes were achieved from a modest school-community linked intervention. The school component contributed to maintaining HRQoL; students who completed the community component derived a range of intra-personal and inter-personal benefits.Trial registrationACTRN12614000446662. April 30th 2014.

Healthy Active Living: A Residence Community–Based Intervention to Increase Physical Activity and Healthy Eating During the Transition to First-Year University

Objective: To examine the effects of a Healthy Active Living (HAL) community intervention on moderate-to-vigorous physical activity (MVPA), fruit and vegetable consumption (FVC), and psychosocial mediators of physical activity among students transitioning into university. Methods: Sixty undergraduate students were assigned to reside in either the HAL community or no-treatment control residence and completed questionnaire measures at the beginning and end of the academic year. Results: Students living in the HAL community reported significantly more MVPA (F[1, 58] = 19.93, p <.001, ηp2 =.26) and greater FVC (F[1, 56] = 3.12, p =.08, ηp2 =.05) compared with controls. Participants in the HAL condition also scored significantly higher in action planning (F[1, 58] = 4.79, p <.05, ηp2 =.08), partially mediating the effect of the intervention on MVPA. Conclusion: A peer-delivered healthy lifestyles intervention targeting first-year university students appears to be effective in preserving or enhancing health behaviors and cognitions during their transition into university life.

Predicting OptimaL cAncer RehabIlitation and Supportive care (POLARIS): rationale and design for meta-analyses of individual patient data of randomized controlled trials that evaluate the effect of physical activity and psychosocial interventions on health-related quality of life in cancer survivors

BackgroundEffective interventions to improve quality of life of cancer survivors are essential. Numerous randomized controlled trials have evaluated the effects of physical activity or psychosocial interventions on health-related quality of life of cancer survivors, with generally small sample sizes and modest effects. Better targeted interventions may result in larger effects. To realize such targeted interventions, we must determine which interventions that are presently available work for which patients, and what the underlying mechanisms are (that is, the moderators and mediators of physical activity and psychosocial interventions). Individual patient data meta-analysis has been described as the ‘gold standard’ of systematic review methodology. Instead of extracting aggregate data from study reports or from authors, the original research data are sought directly from the investigators. Individual patient data meta-analyses allow for adequate statistical analysis of intervention effects and moderators of such effects.Here, we report the rationale and design of the Predicting OptimaL cAncer RehabIlitation and Supportive care (POLARIS) Consortium. The primary aim of POLARIS is 1) to conduct meta-analyses based on individual patient data to evaluate the effect of physical activity and psychosocial interventions on the health-related quality of life of cancer survivors; 2) to identify important demographic, clinical, personal, or intervention-related moderators of the effect; and 3) to build and validate clinical prediction models identifying the most relevant predictors of intervention success.Methods/DesignWe will invite investigators of randomized controlled trials that evaluate the effects of physical activity and/or psychosocial interventions on health-related quality of life compared with a wait-list, usual care or attention control group among adult cancer survivors to join the POLARIS consortium and share their data for use in pooled analyses that will address the proposed aims. We are in the process of identifying eligible randomized controlled trials through literature searches in four databases. To date, we have identified 132 eligible and unique trials.DiscussionThe POLARIS consortium will conduct the first individual patient data meta-analyses in order to generate evidence essential to targeting physical activity and psychosocial programs to the individual survivor’s characteristics, capabilities, and preferences.RegistrationPROSPERO: International prospective register of systematic reviews, CRD42013003805

The Added Value of a Brief Self-Efficacy Coaching on the Effectiveness of a 12-Week Physical Activity Program

Self-efficacy has been found to be an important precondition for behavioral change in sedentary people. The current study examined the effectiveness and added value of including a 15-minute self-efficacy coaching at the start of a 12-week lifestyle physical activity (PA) program. Participants were randomly assigned to a standard-intervention group (without additional self-efficacy coaching, N = 116) or extra-intervention group (with additional self-efficacy coaching, N = 111). Body mass index (BMI), cardiovascular fitness, self-reported PA, and self-efficacy beliefs were assessed at baseline and immediately after the intervention period. Perceived adherence to the PA program was assessed postintervention. At posttest, a significant increase in cardiovascular fitness and decrease in BMI were found in both groups. Significant intervention effects emerged on PA behavior, self-efficacy, and program adherence, in favor of the extra-intervention group. Self-efficacy mediated the intervention effect on program adherence whereas no evidence was found for its role as mediator of PA change. Adding a 15-minute self-efficacy coaching at the start of a lifestyle PA program is a promising strategy to enhance the intervention effects on PA behavior, self-efficacy beliefs, and program adherence. However, the role of self-efficacy as mediator of the intervention effect on in PA was not fully supported.

Psychosocial mediators to physical activity during the perinatal period: A review of the literature

Background: Prenatal physical activity is associated with numerous maternal and child health coutomes. Unfortunately more than half of US women fail to engage in regular exercise during pregnancy. Thus there is a clear need for effective intervention strategies aimed at increasing physical activity among pregnant women. In order to meet this need, the present study provides a systematic review of prospective and intervention studies to identify potential mediators of physical activity during pregnancy. Methods: A systematic review was conducted searching PubMed, MEDLINE, CINAHL, and PsychINFO for prospective studies published from 1995 through 2012 that examined potential mediators to physical activity as well as any intervention studies that sought to increase physical activity levels during pregnancy. Eleven prospective studies that examined potential mediators to physical activity and 3 intervention studies that aimed to increase physical activity during pregnancy were selected that met the inclusion criteria of this review. Articles were reviewed and discussed according to the population, study design, mediators examined (e.g. beliefs pertaining to perceived benefits, barriers, severity and self-efficacy as well as social support, behavioral skills, subjective norms, and behavioral intention), measured outcomes, results, and conclusions of the studies. Results: The review identified several significant mediators of perinatal physical activity such as beliefs (e.g. perceived benefits, barriers, severity and self-efficacy toward physical activity), attitudes, social support, and perceived stress, among others. Conclusions: This review highlights psychosocial mediators that show promise in influencing physical activity behavior. Given that there are very few intervention studies that target these psychosocial mediators more research is warranted in this area.

CHANGES IN PHYSICAL ACTIVITY AND CARDIORESPIRATORY FITNESS ARE MEDIATED BY CHANGES IN MEANINGS OF EXERCISE

As adolescent girls traverse puberty, they become increasingly inactive. Cognitively based theoretical frameworks have failed to explain this dramatic decline. The Theory of Meanings of Behavior asserts that adolescents invest behaviors with affective meanings which are often in opposition to knowledge and beliefs. Meanings of behavior were shown to mediate adolescent eating behaviors but have not been studied as mediators of physical activity. PURPOSE To examine Meanings of Exercise as mediators of the effects of a 4-month intervention on cardiorespiratory fitness in sedentary adolescent girls. METHODS In a preliminary study, 80 girls (ages 11–15) participated in 14 focus groups. Qualitative data analyses yielded a 30-item Meanings of Exercise scale (MES). In this study, participants were 43 girls (14–17 yrs., mean 14.9 yrs; 22% Latina, 17% Asian, 44% White, 17% other). 22 girls participated in a 4 month intensive school-based physical activity program. 21 girls served as controls. Physical activity was measured using a modification of the PDPAR. Metabolic expenditure units (METS) expended in Moderate Physical Activity (MPA, 3 to 6 METS) were calculated using the physical activity compendium. Cardiovascular fitness (V02peak) was determined by a maximal graded cycle ergometer test. Meanings of Exercise were measured using the MES. RESULTS The intervention group showed less decrease in MPA (t = 2.50, df = 40, p < .02) and greater increase in V02 peak (t = 3.29, df = 38, p < .002) than the control group. ANCOVAs showed that the main effect of the intervention on MPA is attributed to changes in four meanings of physical activity (including ‘keeps my mind off bad stuff’ and ‘makes me less sad’) (F > 4.3, p < 0.05). Main effects of the intervention on V02peak is attributed to changes in two meanings (‘don't get bored’ and ‘helps make friends’) (F > 6.6, p < 0.015). CONCLUSION Meanings of Exercise mediated the effects of the intervention on physical activity and cardiorespiratory fitness targeting adolescent girls.

Self-motivation and physical activity among black and white adolescent girls.

The psychometric properties of the Self-Motivation Inventory for children (SMI-C) were established using tests of factorial validity, factorial invariance, latent mean structure, and predictive validity. Adolescent girls from two cohorts (N = 955 and 1797) completed the SMI-C and measures of physical activity, team sport involvement, cardiorespiratory endurance, and body fatness in the 8th grade; participants in cohort 2 ( N= 1658) also completed the measures 1 yr later in the 9th grade. The data were analyzed with exploratory and confirmatory (CFA) factor analysis and structural equation modeling (SEM). The 20-item SMI-C was best represented by a single substantive factor, but there were method effects among the negatively worded items. CFA indicated that a single-factor model fit the nine positively worded items and exhibited strong evidence of cross-validity and factorial invariance between races and across 1 yr; there were no differences in latent means between black and white girls. SEM indicated that the nine-item SMI-C had direct effects on moderate (gamma(11) = 0.16) and vigorous (gamma(21) = 0.22) physical activity and team sport involvement (gamma(31) = 0.29); the effects were invariant between black and white girls, independent of cardiorespiratory endurance and body fatness, and consistent across a 1-yr period. The positively worded nine-item version of the SMI-C can be used in cross-sectional, prospective cohort, and intervention studies that examine self-motivation as a putative moderator or mediator of physical activity among black and white adolescent girls.

Relative Contribution of Psychosocial Variables to the Explanation of Physical Activity in Three Population-Based Adult Samples

Background. Despite large differences in physical activity by demographic subgroup, few studies have identified correlates for specific age and sex groups. The present study quantified the unique variance accounted for in each subgroup by the main psychosocial variables.Methods. Three random samples, ages 16–25, 35–45, and 50–65, with a total of 2,390 Belgian subjects, completed psychosocial questionnaires and were interviewed at home.Results. Social influences, self-efficacy, perceived benefits, and perceived barriers varied in importance by age and sex groups. Social variables provided the most unique information about physical activity for all age and sex groups, except older females. Competition was a significant perceived benefit only for young men, whereas health was the most significant perceived benefit for young women. Among older women and men, health concerns were significant perceived barriers to participation in physical activity.Conclusions. The present results provide hypotheses about mediators of physical activity that can be applied in interventions tailored to the needs of various subgroups.