Cardiometabolic Correlates of Physical Activity and Sedentary Patterns in U.S. Youth.

INTRODUCTION: Daily or weekly averages of physical activity and sedentary behavior could mask patterns of behavior throughout the week that independently affect cardiovascular health. We examined associations between day-to-day physical activity and sedentary behavior latent classes and cardiovascular disease (CVD) risk factors in U.S. youth.

METHODS: Data were from 3984 youth ages 6-17 yr from the National Health and Nutrition Examination Survey (2003-2006) and from previously published accelerometry latent classes characterizing average counts per minute and percent of wear time in moderate-to-vigorous physical activity (MVPA) and sedentary behavior. Multiple linear regression was used to examine associations of the classes with waist circumference, systolic and diastolic blood pressure, HDL-C and LDL-C, triglycerides, glucose, and insulin.

RESULTS: Participants spent 50.4% of the day in sedentary behavior and 5.3% of the day in moderate-to-vigorous physical activity. Average counts per minute were 516.4 for a 7-d period. Significant differences in CVD risk factors were between extreme classes with few differences observed in intermediate classes. Youth in latent class 4 (highest average counts per minute) had lower systolic blood pressure (-4.11 mm Hg, 95% confidence interval [CI] = -7.74 to -0.55), lower glucose (-4.25 mg·dL, 95% CI = -7.84 to -0.66]), and lower insulin (-6.83 μU·mL, 95% CI = -8.66 to -4.99]) compared with youth in class 1 (lowest average counts per minute). Waist circumference was lower for the least sedentary class (-2.54 cm, 95% CI = -4.90 to -0.19) compared with the most sedentary class. Some associations were attenuated when classes were adjusted for mean physical activity or sedentary level.

CONCLUSIONS: There is some indication that patterns, in addition to the total amount of physical activity and sedentary behavior, may be important for cardiovascular health in youth. Longitudinal studies are needed to examine associations between physical activity and sedentary behavior patterns and changes in CVD risk factors.