Christina D. Economos

A Community Intervention Reduces BMI z-score in Children: Shape Up Somerville First Year Results

Objective: The objective was to test the hypothesis that a community‐based environmental change intervention could prevent weight gain in young children (7.6 ± 1.0 years).

Plasma 25-Hydroxyvitamin D Is Associated with Markers of the Insulin Resistant Phenotype in Nondiabetic Adults

We examined the cross-sectional association between plasma 25-hydroxyvitamin D [25(OH)D] and markers of the insulin resistant phenotype. Plasma 25(OH)D concentrations were measured in 808 nondiabetic participants of the Framingham Offspring Study. Outcome measures included fasting and 2-h post 75-g oral glucose tolerance test (OGTT) glucose and insulin; these were used to calculate the homeostatic model assessment-insulin resistance (HOMA-IR) and insulin sensitivity index (ISI(0,120)). We also measured plasma adiponectin, triacylglycerol, and HDL cholesterol concentrations as markers of the insulin-resistant phenotype. After adjusting for age, sex, BMI, waist circumference, and current smoking status, plasma 25(OH)D concentration was inversely associated with fasting plasma glucose and insulin concentrations, and HOMA-IR. Compared with the participants in the lowest tertile category of plasma 25(OH)D, those in the highest tertile category had a 1.6% lower concentration of fasting plasma glucose (P-trend = 0.007), 9.8% lower concentration of fasting plasma insulin (P-trend = 0.001), and 12.7% lower HOMA-IR score (P-trend < 0.001). After adjusting for age and sex, plasma 25(OH)D was positively associated with ISI(0,120), plasma adiponectin, and HDL cholesterol and inversely associated with plasma triacylglycerol, but these associations were no longer significant after further adjustment for BMI, waist circumference, and current smoking status. 25(OH)D and 2-h post-OGTT glucose were not associated. Among adults without diabetes, vitamin D status was inversely associated with surrogate fasting measures of insulin resistance. These results suggest that vitamin D status may be an important determinant for type 2 diabetes mellitus.

Active play and screen time in US children aged 4 to 11 years in relation to sociodemographic and weight status characteristics: a nationally representative cross-sectional analysis

BackgroundThe high prevalence of childhood obesity underscores the importance of monitoring population trends in childrens activity and screen time, and describing associations with child age, gender, race/ethnicity, and weight status. Our objective was to estimate the proportion of young children in the US who have low levels of active play or high levels of screen time, or who have both these behaviors, and to describe associations with age, gender, race/ethnicity, and weight status.MethodsWe analyzed data collected during the National Health and Nutrition Examination Surveys 2001–2004, a US nationally representative cross-sectional study. We studied 2964 children aged 4.00 to 11.99 years. Our main outcomes were reported weekly times that the child played or exercised hard enough to sweat or breathe hard (active play), daily hours the child watched television/videos, used computers, or played computer games (screen time), and the combination of low active play and high screen time. Low active play was defined as active play 6 times or less per week. High screen time was defined as more than 2 hours per day. We accounted for the complex survey design in analyses and report proportions and 95% confidence intervals. We used Wald Chi-square to test for differences between proportions. To identify factors associated with low active play and high screen time, we used multivariate logistic regression.ResultsOf US children aged 4 to 11 years, 37.3% (95% confidence interval, 34.1% to 40.4%) had low levels of active play, 65.0% (95% CI, 61.4% to 68.5%) had high screen time, and 26.3% (95% CI, 23.8% to 28.9%) had both these behaviors. Characteristics associated with a higher probability of simultaneously having low active play and high screen time were older age, female gender, non-Hispanic black race/ethnicity, and having a BMI-for-age ≥95th percentile of the CDC growth reference.ConclusionMany young children in the US are reported to have physical activity and screen time behaviors that are inconsistent with recommendations for healthy pediatric development. Children who are overweight, approaching adolescence, girls, and non-Hispanic blacks may benefit most from public health policies and programs aimed at these behaviors.

Predicted 25-hydroxyvitamin D score and incident type 2 diabetes in the Framingham Offspring Study

BACKGROUND Accumulating evidence suggests that vitamin D is involved in the development of type 2 diabetes (T2D). OBJECTIVE Our objective was to examine the relation between vitamin D status and incidence of T2D. DESIGN We used a subsample of 1972 Framingham Offspring Study participants to develop a regression model to predict plasma 25-hydroxyvitamin D [25(OH)D] concentrations from age, sex, body mass index, month of blood sampling, total vitamin D intake, smoking status, and total energy intake. Using this model, we calculated the predicted 25(OH)D score for each nondiabetic participant at the cohorts fifth examination to assess the association between the predicted 25(OH)D score and incidence of T2D by using Cox proportional hazards models. RESULTS A total of 133 T2D cases were identified over a 7-y average follow-up. In comparison with individuals in the lowest tertile of the predicted 25(OH)D score at baseline, those in the highest tertile had a 40% lower incidence of T2D after adjustment for age, sex, waist circumference, parental history of T2D, hypertension, low HDL cholesterol, elevated triglycerides, impaired fasting glucose, and Dietary Guidelines for Americans Adherence Index score (hazard ratio: 0.60; 95% CI: 0.37, 0.97; P for trend = 0.03). CONCLUSIONS Our findings suggest that higher vitamin D status is associated with decreased risk of T2D. Maintaining optimal 25(OH)D status may be a strategy to prevent the development of T2D.

Parent behavior and child weight status among a diverse group of underserved rural families.

The purpose of this study was threefold: to investigate the association between three parenting behaviors (parenting style, feeding style, and feeding practices), to evaluate whether these behaviors were associated with child weight, and to determine whether style (parenting and feeding) moderated the relationship between feeding practice and child weight. Ninety-nine parent-child dyads were recruited for a cross-sectional study where parents self-reported their parenting style, feeding style, and feeding practices along with demographic characteristics. Height and weight were measured for each dyad. The relationship between parenting style and feeding style showed modest agreement. Feeding style, but not parenting style, was associated with child BMI z-score while controlling for known covariates. An indulgent feeding style was associated with a higher child weight status. Multiple regression analysis demonstrated that feeding style moderated the association between restrictive feeding practices and child BMI z-score. No moderating relationship was found between feeding style and the practices of pressure to eat or monitoring and child weight. This research suggests that an indulgent feeding style may be predictive of higher child weight and that future studies should examine the possible moderating role of feeding style in the parent feeding practice-child weight relationship.

Nutritional practices of elite athletes. Practical recommendations.

SummaryThe nutritional intake of elite athletes is a critical determinant of their athletic performance and ability to compete both physically and mentally. However, their demanding training and travel schedules in addition to a possible lack of nutritional knowledge may prohibit them from maintaining an optimal dietary intake. Sound scientific data about the nutritional habits of elite athletes are limited and, therefore, it is not clear as to whether elite athletes are following nutritional recommendations and maintaining nutritionally sound diets. This review takes a comprehensive look at 22 recent dietary intake studies, including 50 groups of elite athletes. The time period for food record collection ranged from 3 to 7 days except for 2 studies which collected records for 21 and 22 days.Energy intakes of < 50 kcal/kg/day for male athletes who train for < 90 min/day and 45 to 50 kcal/kg/day for female athletes training for < 90 min/day are recommended. Bodyweight should be monitored frequently as a check on calorie intake. With a sufficient calorie intake (1.2 to 2.0 kg/kg/day) protein supplementation is not necessary.Ingested carbohydrate stored as glycogen serves as the primary fuel for muscle performance. Athletes in training should consume 70% of total calories as carbohydrate. Athletes on low energy diets (> 2200 kcal/day) should have a diet of > 25% fat, and athletes with large energy needs should consume 30% fat in their diet. In general, fat intakes should be reduced and carbohydrate intakes increased. Athletes should also restrict alcohol intake during training and competition periods.Athletes with low calorie intakes should consume foods with high contents of iron, calcium, magnesium, zinc and vitamin B12. Athletes with high calorie intakes should consume foods that are naturally high in or fortified with B-group vitamins. Fluid, electrolyte and energy supplementation is desirable to support circulatory, metabolic and thermoregulatory functions. There is no special food that will help elite athletes perform better; the most important aspect of the diet of elite athletes is that it follows the basic guidelines for healthy eating.

Strength improvements with 1 yr of progressive resistance training in older women

Thirty-nine healthy women (59.5 +/- 0.9 yr) were randomized to either a control group (CON) or a progressive resistance training group (PRT) that trained twice weekly for 12 months. PRT trained at 80% or more (average of 84%) of their most recent one repetition maximum (1RM) on the lateral pull-down (LPD), knee extensor (KE), and double leg press (DLP) apparatus. One RM was measured for each exercise once monthly in PRT and at baseline, midstudy, and end of study in CON. One RM significantly increased in PRT for all muscle groups trained compared to CON (P < 0.0001). Increases of 73.7 +/- 12%, 35.1 +/- 3%, and 77.0 +/- 5%, respectively, for KE, DLP, and LPD in PRT and 12.7% +/- 8%, 3.7% +/- 3%, and 18.4% +/- 4%, respectively, in CON were observed. Approximately 50% of the gains in KE and LPD and 40% in the DLP were seen in the first 3 months of the study. In all three exercises, strength gains in PRT continued over the entire 12-month period. These data indicate that high-intensity strength training results in substantial, continual increases in strength in postmenopausal women for at least 12 months, with the greatest gains seen in the first 3 months of training.

Community Interventions: A Brief Overview and Their Application to the Obesity Epidemic

Community-based interventions built on theory and informed by community members produce potent, sustainable change. This intervention model mobilizes inherent community assets and pinpoints specific needs. Advancing community-based research to address obesity will require training of future leaders in this methodology, funding to conduct rigorous trials, and scientific acceptance of this model.

Parent-child interactions and objectively measured child physical activity: a cross-sectional study.

BackgroundParents influence their childrens behaviors directly through specific parenting practices and indirectly through their parenting style. Some practices such as logistical and emotional support have been shown to be positively associated with child physical activity (PA) levels, while for others (e.g. monitoring) the relationship is not clear. The objectives of this study were to determine the relationship between parents PA-related practices, general parenting style, and childrens PA level.MethodsDuring the spring of 2007 a diverse group of 99 parent-child dyads (29% White, 49% Black, 22% Hispanic; 89% mothers) living in low-income rural areas of the US participated in a cross-sectional study. Using validated questionnaires, parents self-reported their parenting style (authoritative, authoritarian, permissive, and uninvolved) and activity-related parenting practices. Height and weight were measured for each dyad and parents reported demographic information. Child PA was measured objectively through accelerometers and expressed as absolute counts and minutes engaged in intensity-specific activity.ResultsSeventy-six children had valid accelerometer data. Children engaged in 113.4 ± 37.0 min. of moderate-vigorous physical activity (MVPA) per day. Children of permissive parents accumulated more minutes of MVPA than those of uninvolved parents (127.5 vs. 97.1, p < 0.05), while parents who provided above average levels of support had children who participated in more minutes of MVPA (114.2 vs. 98.3, p = 0.03). While controlling for known covariates, an uninvolved parenting style was the only parenting behavior associated with child physical activity. Parenting style moderated the association between two parenting practices - reinforcement and monitoring - and child physical activity. Specifically, post-hoc analyses revealed that for the permissive parenting style group, higher levels of parental reinforcement or monitoring were associated with higher levels of child physical activity.ConclusionsThis work extends the current literature by demonstrating the potential moderating role of parenting style on the relationship between activity-related parenting practices and childrens objectively measured physical activity, while controlling for known covariates. Future studies in this area are warranted and, if confirmed, may help to identify the mechanism by which parents influence their childs physical activity behavior.

Shape Up Somerville two-year results: a community-based environmental change intervention sustains weight reduction in children.

OBJECTIVE The objective of this study was to test the hypothesis that community-based environmental change intervention prevents undesirable weight gain in children. METHOD The method used in this study was a two-year, non-randomized, controlled trial (2003-2005) using community-based participatory methodology in three diverse cities in Massachusetts: one intervention and two socio-demographically-matched control communities (pooled for analysis). Children (n=1028), with a mean age=7.61+1.04years participated. Interventions were made to improve energy balance by increasing physical activity options and availability of healthful foods (Year 1). To firmly secure sustainability, the study team supported policies and shifted intervention work to community members (Year 2). RESULTS Change in body mass index z-score (BMIz) was assessed by multiple regression, accounting for clustering within communities and adjusting for baseline covariates. Sex-specific overweight/obesity prevalence, incidence and remission were assessed. Over the two-year period, BMIz of children in the intervention community decreased by -0.06 [p=0.005, 95% confidence interval: -0.08 to -0.04] compared to controls. Prevalence of overweight/obesity decreased in males (OR=0.61, p=0.01) and females (OR=0.78, p=0.01) and remission increased in males (OR 3.18, p=0.03) and females (OR 1.93, p=0.03) in intervention compared to controls. CONCLUSION Results demonstrate promise for preventing childhood obesity using a sustainable multi-level community-based model and reinforce the need for wide-reaching environmental and policy interventions.