LAUSR

Introduction: Previous studies have revealed a significant, inverse dose-response relationship between total activity counts/day (TAC/d) and several cardiometabolic risk factors (CMRF). An ongoing line of research is the examination of the contributions of behavioral, environmental, and physiological factors to CMRF differences across race-ethnicity. However, it is unknown if these differences exist among the most physically active adults. Hypothesis: Among the most active U.S. adults, we hypothesize that CMRF measures will differ across race-ethnic groups. Methods: Study sample (n=1,059) included adult (20-79 years of age) participants from the 2003-2006 NHANES who wore an ActiGraph model 7164 accelerometer on the right hip. The top quartile of accelerometer-derived age- and gender-specific TAC/d was used as a cutpoint to define the “most active”. All participants were without T2D (fasting glucose <126 mg/dL, no medication, no self-reported diagnosis) and without CVD (self-report). CMRF included HOMA-IR, fasting insulin and glucose, systolic (SBP) and diastolic blood pressure (DBP), HDL, LDL, triglycerides, BMI, waist circumference (WC) and C-reactive protein (CRP). Multiple linear regression was used to examine CMRF differences between non-Hispanic white (NHW), non-Hispanic black (NHB) and Mexican American (MA) participants. Regression models were adjusted for age, sex, education, smoking, wear time, BMI (except BMI and WC models), objectively-measure MVPA (≥760 counts/min) and race-ethnicity. Results: No significant differences were found in mean TAC/d across race-ethnicity. When compared to NHW, NHB had significantly higher HOMA-IR, fasting insulin, SBP, WC, and BMI. Compared to NHW, MA had significantly higher HOMA-IR, fasting insulin, triglycerides, WC and BMI. When comparing NHB to MA, MA had significantly higher triglycerides and HDL and significantly lower SBP. Conclusions: It has been proposed that the race-ethnic differences in PA participation could be contributing to disparities in elevated CMRF, but even among U.S. adults in the 75th percentile for total activity volume (i.e. TAC/d), race-ethnic differences in CMRF still exist. It is probable that other social, environmental, and genetic factors are responsible for moderating the beneficial effects PA has on CMRF specifically among NHB and MA adults.