Adjusted restricted cubic spline model showing the difference in 25(OH)D (95% CIs) by PA levels (in METS*min/wk) at ARIC visit 1 in the overall study. The model was adjusted age, sex, race/center, education, smoking status, alcohol intake, SBP, antihypertensive medication use, diabetes, total and HDL cholesterol, use of lipid-lowering medications, estimated GFR, and BMI.