Active commuting to school and association with physical activity and adiposity among US youth

Background: Walking or bicycling to school (ie, active commuting) has shown promise for improving physical activity and preventing obesity in youth. Our objectives were to examine, among US youth, whether active commuting was inversely associated with adiposity and positively associated with moderate-to-vigorous physical activity (MVPA). We also examined whether MVPA mediated the relationships between active commuting and adiposity.

Methods: Using data of participants aged 12 to 19 years from the US National Health and Nutrition Examination Survey 2003 to 2004 (n = 789 unweighted), we constructed multiple linear regression models that controlled for dietary energy intake and sociodemographics. The main exposure variable was active commuting. The outcomes were BMI z-score, waist circumference, skinfolds and objectively measured MVPA. The product-of-coefficients method was used to test for mediation.

Results: Active commuting was inversely associated with BMI z-score (β = –0.07, P = .046) and skinfolds (β = –0.06, P = .029), and positively associated with overall daily (β = 0.12, P = .024) and before- and after-school (β = 0.20, P < .001) MVPA. Greater before- and after-school MVPA explained part of the relationship between active commuting and waist circumference (Sobel z = –1.98, P = .048).

Conclusions: Active commuting was associated with greater MVPA and lower measures of adiposity among US youth. Before- and after-school MVPA mediated the relationships between active commuting and waist circumference.

Adolescents’ physical activity : competition between perceived neighborhood sport facilities and home media resources

Objective. To examine the independent, competing, and interactive effects of perceived availability of specific types of media in the home and neighborhood sport facilities on adolescents’ leisure-time physical activity (PA).

Methods. Survey data from 34 369 students in 42 Hong Kong secondary schools were collected (2006–07). Respondents reported moderate-to-vigorous leisure-time PA, presence of sport facilities in the neighborhood and of media equipment in the home. Being sufficiently physically active was defined as engaging in at least 30 minutes of non-school leisure-time PA on a daily basis. Logistic regression and post-estimation linear combinations of regression coefficients were used to examine the independent and competing effects of sport facilities and media equipment on leisure-time PA.

Results. Perceived availability of sport facilities was positively (ORboys = 1.17; ORgirls = 1.26), and that of computer/Internet negatively (ORboys = 0.48; ORgirls = 0.41), associated with being sufficiently active. A significant positive association between video game console and being sufficiently active was found in girls (ORgirls = 1.19) but not in boys. Compared with adolescents without sport facilities and media equipment, those who reported sport facilities only were more likely to be physically active (ORboys = 1.26; ORgirls = 1.34), while those who additionally reported computer/Internet were less likely to be physically active (ORboys = 0.60; ORgirls = 0.54).

Conclusions. Perceived availability of sport facilities in the neighborhood may positively impact on adolescents’ level of physical activity. However, having computer/Internet may cancel out the effects of active opportunities in the neighborhood. This suggests that physical activity programs for adolescents need to consider limiting the access to computer-mediated communication as an important intervention component.

A commentary on current practice in mediating variable analyses in behavioural nutrition and physical activity

Objective : To critique current practice in, and provide recommendations for, mediating variable analyses (MVA) of nutrition and physical activity behaviour change.

Strategy : Theory-based behavioural nutrition and physical activity interventions aim at changing mediating variables that are hypothesized to be responsible for changes in the outcome of interest. MVA are useful because they help to identify the most promising theoretical approaches, mediators and intervention components for behaviour change. However, the current literature suggests that MVA are often inappropriately conducted, poorly understood and inadequately presented. Main problems encountered in the published literature are explained and suggestions for overcoming weaknesses of current practice are proposed.

Conclusion : The use of the most appropriate, currently available methods of MVA, and a correct, comprehensive presentation and interpretation of their findings, is of paramount importance for understanding how obesity can be treated and prevented.

Explaining the effects of a 1-year intervention promoting physical activity in middle schools: a mediation analysis

Objective : The aim of the present study was to examine the mediation effects of changes in psychosocial determinants of physical activity (attitude, social support, self-efficacy, perceived benefits and barriers) on changes in physical activity.

Design : One-year intervention study with baseline and 1-year post measures of physical activity habits and psychosocial correlates.

Setting : Fifteen middle schools. Subjects : Boys and girls (n = 2840) aged 11–15 years completed the validated questionnaires during class hours.

Results : The product-of-coefficients test was used to asses the mediating effects. Self-efficacy for physical activity at school was found to be the only significant mediator of physical activity change. Specifically, self-efficacy for physical activity at school partly mediated the effect of the intervention on total and school-related physical activity change in the intervention group with parental support (P < 0.05). None of the other potential mediators, attitudes, social support, perceived benefits and perceived barriers, seemed to have had a positive effect. Even a suppressor effect was found for attitudes. Given that the effects of self-efficacy and attitudes were of opposite direction, the total mediated/suppressed effects of the intervention were not statistically significant.

Conclusions : Positive changes in total and school-related physical activity in adolescents could be partly explained by increases in self-efficacy for physical activity at school through a physical activity intervention in middle schools with parental support. However, the suppressor effect of attitudes decreased this effect. As this is one of the first true mediation analyses in this age group, further research is needed to replicate the importance of these mediators.

Physical activity, activity change, and their correlates in a population-based sample of colorectal cancer survivors

Background: Physical activity can provide benefits to cancer survivors, including reduced symptoms and treatment side effects, improved overall quality of life, and decreased risk of other chronic diseases.

Purpose: The aim of the study was to describe physical activity before and after diagnosis of colorectal cancer and to examine the associations with sociodemographic and disease-related variables.

Methods: Telephone interviews were conducted with 1,996 colorectal cancer survivors recruited through a cancer registry.

Results: In comparison to prediagnosis activity levels, there were 21% fewer participants meeting the physical activity and health guideline (150 min of moderate-intensity physical activity per week) postdiagnosis. Meeting the guideline postdiagnosis was associated with being male, living outside of the state capital city, having a higher education, having a healthy body mass index, not smoking, having had surgery only, and no reported fatigue. Attributes associated with a decrease in physical activity following diagnosis were being female, living within the state capital city, having a lower level of education, having a stoma, having adjuvant therapy, and experiencing fatigue.

Conclusions: There is considerable scope for targeted interventions to increase the physical activity of colorectal cancer survivors, particularly for those groups that we have identified as being less active and/or have reduced their activity.

Associations of leisure-time physical activity with quality of life in a large, population-based sample of colorectal cancer survivors

Objective : To examine the associations between physical activity and quality of life for colorectal cancer survivors; and to describe the associations of medical and sociodemographic attributes with overall quality of life, and their moderating effects on the relationships between physical activity and quality of life.

Methods : Telephone interviews were conducted with 1,996 colorectal cancer survivors recruited through the Queensland Cancer Registry. Data were collected on current quality of life; leisure-time physical activity pre- and post-diagnosis; cancer treatment and side-effects; and general sociodemographic attributes. Hierarchical generalized linear models identified variables significantly associated with quality of life.

Results : After controlling for sociodemographic variables, disease-specific variables, treatment side-effects, and pre-diagnosis leisure-time physical activity, there were significant differences in quality of life scores by post-diagnosis physical activity category. Compared to participants who were inactive after their diagnosis, those who were sufficiently active had a 17.0% higher total quality of life score. Physical activity also had a significant independent positive association with the physical well-being, functional well-being, and additional concerns subscales of the FACT-C.

Conclusions : Our findings demonstrate that quite modest changes in leisure-time physical activity are associated with quality of life. Colorectal cancer survivors may benefit from a more active lifestyle.

Neighborhood and individual socio-economic variations in the contribution of occupational physical activity to total physical activity

Background: There is an inverse relationship between individual socio-economic status (SES) and amount of occupational physical activity. The role of the socio-economic environment is, however, less clear. This study examined the independent influences of neighborhood and individual SES on absolute and relative amount of occupational physical activity. It also examined the moderating effects of neighborhood SES on the relationship between individual SES and occupational physical activity.

Methods: Employees (n = 1236) resident in high or low SES neighborhoods were assessed on socio-demographic factors, including educational attainment and household income, and physical activity.

Results: Neighborhood SES and individual SES were independently inversely related to absolute and relative amount of occupational physical activity. Significant interactions between neighborhood SES and level of educational attainment in the contribution of total and vigorous occupational physical activity to total physical activity were found.

Conclusions: Neighborhood SES can function as a moderator in the relationship between individual SES and occupational physical activity.

Physical activity of young children

Occupational therapists concerned with the long-term health and welfare of children need be aware of the decline in physical activity of children in most Western societies. The current study examined the extent of physical activity in the lives of 50 Australian children with mean age of 7.74 years through questionnaires completed by the children’s parents and pedometer (step) data collected from the children during 4 days. The current data show that higher self-perception of physical competence, child’s levels of physical skill, and low parental perception of peer teasing were the best predictors of physical activity. Higher family socioeconomic status was found to be a significant predictor of more steps being taken on weekends, and partner’s (usually a father’s) level of exercise was an important predictor of the number of weekend steps. Children who were perceived to experience more peer teasing completed fewer steps the weekend. The findings from this study indicate that children’s physical activity levels depend on the availability of family resources, and that children in their early school years already experience negative effects from teasing that, combined with reduced self-confidence, may lay the foundation for their withdrawing from physical activity as they get older.

Physical activity, sedentary behavior, and postnatal depressive symptoms: a review

Context:
Postnatal depression is highly prevalent in mothers. Although physical activity has been found to reduce the risk of depression in the general population, little is known regarding its link with postnatal depression. This review examined original research investigating the relationship between physical activity and sedentary behavior dose (frequency, intensity, and duration) and domain, and postnatal depressive symptoms. 

Evidence acquisition:
A systematic search for original research investigating the relationship between physical activity and sedentary behavior dose and domain, and postnatal depressive symptoms, was performed using several electronic databases in early 2012. A total of ten observational and seven intervention studies were included. 

Evidence synthesis:
Most studies (one cross-sectional, two longitudinal, and six intervention studies) found an inverse association between postpartum leisure-time physical activity (LTPA) and postnatal depressive symptoms. One longitudinal study found that occupational physical activity was positively associated with postnatal depressive symptoms. There was inconclusive evidence to suggest an optimal dose of postpartum physical activity for reducing postnatal depressive symptoms. Two longitudinal studies found an inverse association between antenatal LTPA and presence of postnatal depressive symptoms. One of two studies that investigated sedentary behavior found a positive cross-sectional association between sedentary behavior and presence of postnatal depressive symptoms.

Conclusions:
Although studies are limited, on balance, LTPA prior to, during, and after pregnancy may be important for reducing the risk of postnatal depression. Further research is required to determine the optimal dose and domain of physical activity for reducing postnatal depressive symptoms as well as to examine the link between  sedentary behavior and postnatal depressive symptoms.

Researching the relationship between physical activity and motherhood in older Somali women

This thesis explores participation in physical activity by a group of older Somali women living in Melbourne, Australia. First, it describes the methodological challenges faced by a white researcher conducting cross-cultural research; second, it explores how participants' experiences of motherhood and physical activity in Somalia and Australia influence their participation in physical activity. This research contributes data to address the scarcity of knowledge and research on physical activity amongst older African and Muslim women.

Associations between psychological stress, eating, physical activity, sedentary behaviours and body weight among women: a longitudinal study

Background: