Soyang Kwon

Sustained Effect of Early Physical Activity on Body Fat Mass in Older Children

BACKGROUND Physical activity is assumed to reduce excessive fatness in children. This study examined whether the benefits of early childhood moderate-to-vigorous physical activity (MVPA) on fatness are sustained throughout childhood. METHODS MVPA minutes per day (min/d) and fat mass (kilograms; kg) were measured using accelerometry and dual-energy x-ray absorptiometry in 333 children aged 5, 8, and 11 years who were participating in the Iowa Bone Development Study. Mixed regression models were used to test whether MVPA at age 5 years had an effect on fat mass at age 8 years and age 11 years, after adjustment for concurrent height, weight, age, maturity, and MVPA. The analysis was repeated to control for fat mass at age 5 years. Using mixed-model least-squares means, adjusted means of fat mass at age 8 years and age 11 years were compared between the highest and lowest quartiles of MVPA at age 5 years. Data were collected between 1998 and 2006 and analyzed in 2008. RESULTS For boys and girls, MVPA at age 5 years was a predictor of adjusted fat mass at age 8 years and age 11 years (p<0.05). In girls, the effect of MVPA at age 5 years was not significant when fat mass at age 5 years was included. Boys and girls in the highest quartile of MVPA at age 5 years had a lower fat mass at age 8 years and age 11 years than children in the lowest MVPA quartile at age 5 years (p<0.05; mean difference 0.85 kg at age 8 years and 1.55 kg at age 11 years). CONCLUSIONS Some effects of early-childhood MVPA on fatness appear to persist throughout childhood. Results indicate the potential importance of increasing MVPA in young children as a strategy to reduce later fat gains.

Developmental Trajectories of Physical Activity, Sports, and Television Viewing During Childhood to Young Adulthood: Iowa Bone Development Study

IMPORTANCE The diverse developmental patterns of obesogenic behaviors during childhood and adolescence can be better understood by using new analytic approaches to assess the heterogeneity in variation during growth and development and to map the clustering of behavior patterns. OBJECTIVES To identify distinct trajectories of daily time spent in moderate- to vigorous-intensity physical activity (MVPA) from ages 5 to 19 years and to examine the associations of MVPA trajectories with sports participation and television viewing trajectories. DESIGN, SETTING, AND PARTICIPANTS Cohort members in the prospective population-based Iowa Bone Development Study participated in MVPA assessments via accelerometry from September 16, 1998, to December 9, 2013, at ages 5, 8, 11, 13, 15, 17, and 19 years and completed a questionnaire every 6 months on sports participation and daily time spent in television viewing. MAIN OUTCOMES AND MEASURES Trajectories of MVPA (minutes per day), participation in organized sports (yes or no), and television viewing time (hours per day). RESULTS Based on the data from 537 participants (50.1% females; 94.6% white), we identified 4 MVPA trajectories: consistently inactive (14.9%), consistently active (18.1%), decreasing moderate physical activity (52.9%), and substantially decreasing high physical activity (14.1%). All participants in the consistently inactive trajectory also followed a trajectory of no participation in sports. The consistently active trajectory was associated with decreasing an already low television viewing trajectory (P < .001). CONCLUSIONS AND RELEVANCE This study provided a nuanced look at the known decrease in MVPA during childhood and adolescence. Sports participation could be a critical way to avoid the consistently inactive pattern. Most important, we identified a subset of participants who maintained a seemingly healthy level of MVPA from childhood to young adulthood. The developmental pathways of physical activity and television viewing behaviors could be related. Additional studies should examine the determinants and health consequences of these specific MVPA trajectories.

Tracking of accelerometry-measured physical activity during childhood: ICAD pooled analysis

BackgroundUnderstanding of physical activity (PA) tracking during childhood is important to predict PA behaviors and design appropriate interventions. We compared tracking of PA according to PA level and type of day (weekday/weekend) in a pool of five children’s cohort studies.MethodsData from ALSPAC, CLAN, Iowa Bone Development Study, HEAPS, PEACH were extracted from the International Children’s Accelerometry Database (ICAD), resulting in 5,016 participants with age, gender, and accelerometry data at both baseline and follow-up (mean age: 10.3 years at baseline, 12.5 years at follow-up). Daily minutes spent in moderate- and vigorous-intensity PA (MVPA) and vigorous-intensity PA (VPA) was categorized into quintiles. Multinomial logistic regression models were fit to predict follow-up (M)VPA from baseline (M)VPA (reference: 20- < 80%tile), age at follow-up, and follow-up duration.ResultsFor the weekday, VPA tracking for boys with high baseline VPA was higher than boys with low baseline VPA (ORs: 3.9 [95% CI: 3.1, 5.0] vs. 2.1 [95% CI: 1.6, 2.6]). Among girls, high VPA was less stable when compared low VPA (ORs: 1.8 [95% CI: 1.4, 2.2] vs. 2.6 [95% CI: 2.1, 3.2]). The pattern was similar for MVPA among girls (ORs: 1.6 [95% CI: 1.2, 2.0] vs. 2.8 [95% CI: 2.3, 3.6]). Overall, tracking was lower for the weekend.ConclusionsPA tracking was higher on the weekday than the weekend, and among inactive girls than active girls. The PA “routine” of weekdays should be used to help children establish healthy PA patterns. Supports for PA increase and maintenance of girls are needed.

Breaks in Sedentary Time during Childhood and Adolescence: Iowa Bone Development Study

PURPOSE The frequency of interruptions in sedentary time (sedentary breaks) is an aspect of sedentary behaviors that may be associated with metabolic health outcomes. The aim of this study was to describe the change in the frequency of sedentary breaks during a 10-yr period from ages 5 to 15 yr. METHODS The longitudinal Iowa Bone Development Study has collected accelerometry data at approximately 5, 8, 11, 13, and 15 yr. Data from participants who wore an accelerometer at least 10 h·d(-1) and 3 d per data collection episode were used (423 children at age 5 yr, 550 children at age 8 yr, 520 children at age 11 yr, 454 children at age 13 yr, and 344 children at age 15 yr). The frequency of sedentary breaks was determined based on accelerometry data and compared by weekday/weekend, period during the day, gender, and data collection episode. RESULTS The frequency of sedentary breaks decreased by >200 times per day during a 10-yr period from ages 5 to 15 yr. Linear regression models estimated a 1.84-times-per-hour decrease per year for boys and a 2.04-times-per-hour decrease per year for girls (P values < 0.0001). Both boys and girls showed significantly fewer breaks on weekdays from morning to 3:00 p.m. than on weekends from morning to 3:00 p.m. (P values < 0.0001). The frequency of sedentary breaks was slightly higher among boys than among girls (gender difference ≤ 2 times per hour; P values < 0.01 at ages 11, 13, and 15 yr). CONCLUSIONS Breaks in sedentary time notably decrease during childhood and adolescence. During school hours, boys and girls have fewer breaks in sedentary time than during any other period of weekday or weekend day.

Nutrient content of school meals before and after implementation of nutrition recommendations in five school districts across two U.S. counties

OBJECTIVE To compare changes in nutrient levels of school meals before and after implementation of nutrition interventions at five school districts in two, large U.S. counties. School menu changes were compared against national school meal recommendations. METHODS A large urban school district in Los Angeles County (LAC), California and four school districts in suburban Cook County (SCC), Illinois implemented school meal nutrition interventions. Nutrition analyses were conducted for school breakfast and lunch before and after changes were made to the meal programs. Means, % change, and net calories (kilocalories or kcal) offered as a result of the nutrition interventions were calculated. RESULTS School districts in both counties made district-wide changes in their school breakfast and lunch menus. Menu changes resulted in a net reduction of calories, sugar, and sodium content offered in the meals. Net fewer calories offered as a result of the nutrition interventions were estimated to be about 64,075kcal per student per year for LAC and 22,887kcal per student per year for SCC. CONCLUSIONS Nutrition interventions can have broad reach through changes in menu offerings to school-aged children and adolescents. However, further research is needed to examine how these changes affect student food selection and consumption.

Active lifestyle in childhood and adolescence prevents obesity development in young adulthood

To test the hypothesis that individuals who are active but who decrease physical activity (PA) over time have a higher risk of becoming obese in young adulthood, when compared to individuals who are consistently active throughout childhood and adolescence.

Recognition of elevated blood pressure in an outpatient pediatric tertiary care setting.

OBJECTIVE To assess the prevalence of elevated blood pressure (BP) and its identification among outpatients at a pediatric tertiary care hospital and to assess clinician attitudes towards BP management. STUDY DESIGN A retrospective review was undertaken of electronic medical record data of visits over the course of 1 year to 10 subspecialty divisions and 3 primary care services at an urban tertiary care hospital. Interviews of division/service representatives and a clinician survey on perceived role on BP care, practices, and protocols related to BP management were conducted. Elevated BP was defined as ≥90th percentile (using US references); identification of elevated BP was defined as the presence of appropriate codes in the problem list or visit diagnoses. RESULTS Among 29,000 patients (ages 2-17 years), 70% (those with ≥1 BP measurement) were analyzed. Patients were as follows: 50% male; 42% white, 31% Hispanic, 16% black, 5% Asian, and 5% other/missing; 52% had Medicaid insurance. A total of 64% had normal BPs, 33% had 1-2 elevated BP measurements, and 3% had ≥3 elevated BP measurements. Among those with ≥3 elevated BP measurements, the median frequency of identification by division/service was 17%; the greatest identification was for Kidney Diseases (67%), Wellness & Weight Management (60%), and Cardiology (33%). Among patients with ≥3 elevated BP measurements, 21% were identified vs 7% identified among those with 1-2 increased measurements (P<.001). All clinician survey respondents perceived self-responsibility for identification of elevated BP, but opinions varied for their role in the management of elevated BP. CONCLUSIONS The identification of patients with elevated BP measurements was low. Strategies to increase the identification of elevated BPs in outpatient tertiary care settings are needed.

Urban crash-related child pedestrian injury incidence and characteristics associated with injury severity

OBJECTIVE Describe age-based urban pedestrian versus auto crash characteristics and identify crash characteristics associated with injury severity. MATERIALS AND METHODS Secondary analysis of the 2004-2010 National Highway and Traffic Safety Administration database for Illinois. All persons in Chicago crashes with age data who were listed as pedestrians (n=7175 child age ≤19 yo, n=16,398 adult age ≥20 yo) were included. Incidence and crash characteristics were analyzed by age groups and year. Main outcome measures were incidence, crash setting, and injury severity. Multivariate logistic regression analysis was performed to estimate injury severity by crash characteristics. RESULTS Overall incidence was higher for child (146.6 per 100,000) versus adult (117.3 per 100,000) pedestrians but case fatality rate was lower (0.7% for children, 1.7% for adults). Child but not adult pedestrian injury incidence declined over time (trend test p<0.0001 for <5 yo, 5-9 yo, and 10-14 yo; p<0.05 for 15-19 yo, p=0.96 for ≥20 yo). Most crashes for both children and adults took place during optimal driving conditions. Injuries were more frequent during warmer months for younger age groups compared to older (χ(2)p<0.001). Midblock crashes increased as age decreased (p<0.0001 for trend). Most crashes occurred at sites with sub-optimal traffic controls but varied by age (p<0.0001 for trend). Crashes were more likely to be during daylight on dry roads in clear weather conditions for younger age groups compared to older (χ(2)p<0.001). Daylight was associated with less severe injury (child OR 0.93, 95% CI 0.87-0.98; adult OR 0.90, 95% CI 0.87-0.93). CONCLUSION The incidence of urban pedestrian crashes declined over time for child subgroups but not for adults. The setting of pedestrian crashes in Chicago today varies by age but is similar to that seen in other urban locales previously. Injuries for all age groups tend to be less severe during daylight conditions. Age-based prevention efforts may prove beneficial.

Validation of a Novel Physical Activity Assessment Device in Morbidly Obese Females

Assessment of physical activity in morbidly obese subjects is important especially in bariatric surgery. We examined the validity of Intelligent Device for Energy Expenditure and Activity (IDEEA) for measuring physical activity and sedentary behavior in morbidly obese women. Activity types, gait counts, and speed detected by the IDEEA monitor were compared to those reported by an observer. The IDEEA monitor detected activity types and gait counts with relatively high accuracy, although slightly lower in extremely obese women than in normal weight controls. The IDEEA monitor accurately estimated gait speeds in both groups. Since gait speed predicts energy expenditure more accurately than gait counts, it is of greater clinical relevance. Reliability of the IDEEA monitor was excellent. The IDEEA monitor is a valid instrument for measuring physical activity and sedentary behavior in extremely obese women, and therefore has potential applications in bariatric surgery both in preoperative evaluation and long-term follow-up.

Socioeconomic Disconnection as a Risk Factor for Increased HIV Infection in Young Men Who Have Sex with Men

PURPOSE HIV disproportionately affects young men who have sex with men (YMSM), particularly black YMSM. Increasingly, researchers are turning to social, economic, and structural factors to explain these disproportionate rates. In this study, we explore the relationship between socioeconomic disconnection and HIV status and factors related to HIV infection, including drug use, condomless anal sex, and binge drinking. We operationalize socioeconomic disconnection in this young population as lack of engagement in educational and employment opportunities. METHODS Baseline data were analyzed from a longitudinal cohort study of YMSM aged 16-20 years recruited from the Chicago area (N = 450). Bivariate analyses of the association of socioeconomic disconnection and HIV-positive status, drug and alcohol use, and condomless anal sex were assessed using chi-square tests. The relationship of socioeconomic disconnection and HIV-positive status was then examined in multivariate logistic regression models, controlling for age and race/ethnicity and significant behavioral factors. RESULTS Among study participants, 112 (25%) were not in school, 310 (69%) were not currently working, and 81 (18%) were neither in school nor working. Black MSM were more likely to be socioeconomically disconnected (neither in school nor working; n = 56, 23.3%). The results revealed that disconnected YMSM were more likely to binge drink (AOR = 2.34; 95% CI = 1.16, 4.74) and be HIV positive (AOR = 2.24; 95% CI = 1.04, 4.83). Subpopulation analysis for black participants revealed similar associations (AOR of binge drinking = 2.92; 95% CI = 1.07, 8.01; AOR of HIV positive = 2.38; 95% CI = 1.03, 5.51). Controlling for substance use, the association between disconnection and HIV-positive status remained significant (AOR = 2.37; 95% CI = 1.08, 5.20). CONCLUSION Socioeconomic disconnection is significantly and positively associated with HIV status among YMSM, suggesting that the two factors are related. Socioeconomic factors present an important area for future research focusing on HIV infection in this high-risk group.