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  • Author: Nicholas M. Edwards x
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Nicholas M. Edwards, Heidi J. Kalkwarf, Jessica G. Woo, Philip R. Khoury, Stephen R. Daniels and Elaine M. Urbina

Purpose:

The objective of this study was to characterize the relationship between objectively-measured physical activity (PA) and cardiovascular risk factors in 7-year-old children and test the hypothesis that it differs by race.

Methods:

Cross-sectional study of 308 7-year-old children drawn from a major US metropolitan community. PA (moderate-to-vigorous, MVPA; light, LPA; and inactivity, IA) was measured by accelerometry (RT3). Cardiovascular risk factors included BMI, blood pressure, and serum lipids, glucose and insulin concentrations. General linear modeling was used to evaluate the independent associations between PA measures and cardiovascular risk factors and interactions by race.

Results:

In black children, greater time spent in PA was independently associated with lower levels of triglycerides (MVPA and LPA, both p < .01), glucose (MVPA, p < .05), and insulin (MVPA, p < .01); these associations were not evident in white children. Across races, greater inactivity was independently associated with greater low-density lipoprotein cholesterol in overweight participants (p < .01) but not in normal weight participants. No PA measure was associated with BMI, systolic blood pressure, or high-density lipoprotein cholesterol.

Conclusions:

In this cohort of 7-year-old children, the relationship between PA and some cardiovascular risk factors differed by race. These findings may have implications for targeting of PA promotion efforts in children.

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Nicholas M. Edwards, Philip R. Khoury, Heidi J. Kalkwarf, Jessica G. Woo, Randal P. Claytor and Stephen R. Daniels

Establishing and maintaining healthy physical activity (PA) levels is important throughout life. The purpose of this study was to determine the extent of PA tracking between ages 3 and 7 y. Objective measures of PA (RT3, triaxial accelerometer) were collected every 4 mo from ages 3–7; data from 234 children with PA measures available during each year of age were analyzed. Mean PA (total, moderate/vigorous (MV), and inactivity [IA]) was calculated for each year of age and adjusted for wear time. Correlations with age 3 PA were moderate at age 4 (r = .42−.45) but declined by age 7 (r = .19−.25). After classification into sex-specific tertiles of PA at age 3, boys in the high age 3 MVPA tertile maintained significantly higher PA at all subsequent ages, while girls in the high age 3 MVPA tertile were not significantly higher at age 6 and 7. Boys and girls in the high age 3 IA tertile had significantly higher IA at multiple subsequent years of age (p < .05 at ages 5 and 6). In conclusion, boys who were relatively more active at age 3 remained more active for several subsequent years. These findings highlight early-childhood differences in physical activity patterns between boys and girls.

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Samuel G. Wittekind, Nicholas M. Edwards, Philip R. Khoury, Connie E. McCoy, Lawrence M. Dolan, Thomas R. Kimball and Elaine M. Urbina

Background: We aimed to (1) compare a subjective and objective measure of habitual physical activity (PA), (2) determine the association of PA and cardiovascular risk factors, and (3) test the hypothesis that PA is an independent determinant of target organ damage in youth. Methods: Cross-sectional analysis of youth with and without type 2 diabetes [mean age = 22 (3.9) y]. PA was measured with International Physical Activity Questionnaire and Actical accelerometer. Target organ damage was assessed with echocardiography and peripheral arterial testing. Subjects were stratified into tertiles of total PA, and differences were tested by analysis of variance and χ2 tests. General linear models tested for independent associations. Results: The correlation between International Physical Activity Questionnaire and accelerometry was weak (r = .23, P = .0003). Less active subjects had worse cardiovascular risk profiles and target organ damage, including stiffer arteries (P < .01). These outcome differences did not reach statistical significance when adjusted for covariates, such as lipid levels and glycemic control. Conclusion: Survey assessment of PA is complicated by inaccurate reporting. There is a strong association of habitual PA with cardiovascular risk factor clustering. PA may exert its beneficial effect on arterial stiffness in obese youth through improved glycemic control.

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Nicholas W. Baumgartner, Anne M. Walk, Caitlyn G. Edwards, Alicia R. Covello, Morgan R. Chojnacki, Ginger E. Reeser, Andrew M. Taylor, Hannah D. Holscher and Naiman A. Khan

Background: Physical inactivity and excess adiposity are thought to be detrimental to physical and cognitive health. However, implications of these interrelated health factors are rarely examined together; consequently, little is known regarding the concomitant contribution of physical activity and adiposity to cognition. Methods: Bivariate correlations and hierarchical linear regressions were conducted among a sample of adults between 25 and 45 years (N = 65). Attentional inhibition was assessed using an Eriksen Flanker task. Whole-body percent body fat (%Fat) was assessed using dual-energy X-ray absorptiometry. Daily percent time spent in moderate to vigorous physical activity (%MVPA) was monitored using an accelerometer (7 d). Results: After adjusting for significant covariates, %MVPA was a positive predictor of accuracy in the incongruent task (β = 0.31, P = .03). Individuals who engaged in greater %MVPA exhibited superior attentional inhibition. Additionally, there was an interaction effect of %Fat and %MVPA on attentional inhibition (β = 0.45, P = .04). Conclusion: The positive influence of MVPA on cognitive control persists following the adjustment of significant covariates and adiposity. Additionally, interactive effects between %Fat and %MVPA suggest that individuals with lower activity and greater adiposity exhibited poorer attentional inhibition. These findings have relevance for public health given the elevated rates of physical inactivity and obesity.

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Nicholas M. Edwards, Gregory D. Myer, Heidi J. Kalkwarf, Jessica G. Woo, Philip R. Khoury, Timothy E. Hewett and Stephen R. Daniels

Objective:

Evaluate effects of local weather conditions on physical activity in early childhood.

Methods:

Longitudinal prospective cohort study of 372 children, 3 years old at enrollment, drawn from a major US metropolitan community. Accelerometer-measured (RT3) physical activity was collected every 4 months over 5 years and matched with daily weather measures: day length, heating/cooling degrees (degrees mean temperature < 65°F or ≥ 65°F, respectively), wind, and precipitation. Mixed regression analyses, adjusted for repeated measures, were used to test the relationship between weather and physical activity.

Results:

Precipitation and wind speed were negatively associated with total physical activity and moderate-vigorous physical activity (P < .0001). Heating and cooling degrees were negatively associated with total physical activity and moderate-vigorous physical activity and positively associated with inactivity (all P < .0001), independent of age, sex, race, BMI, day length, wind, and precipitation. For every 10 additional heating degrees there was a 5-minute daily reduction in moderatevigorous physical activity. For every additional 10 cooling degrees there was a 17-minute reduction in moderate-to-vigorous physical activity.

Conclusions:

Inclement weather (higher/lower temperature, greater wind speed, more rain/snow) is associated with less physical activity in young children. These deleterious effects should be considered when planning physical activity research, interventions, and policies.