Table 2.

Cross-Sectional Association Between Cardiorespiratory Fitness and Measures of Adiposity with Heart Rate Variability at Year 20, CARDIA

Independent variable		OR per 1-SD increment in independent variable	95% CI	P value
Lower 25th percentile of SDNN (ms)
Graded exercise test duration (s) SD: 159 s	Model 1	0.781	0.683, 0.894	0.0003
	Model 2a: Model 1 + WC	0.778	0.660, 0.918	0.0029
	Model 2b: Model 1 + BMI	0.755	0.641, 0.889	0.0007
Waist circumference (cm) SD: 15 cm	Model 1	1.121	1.005, 1.250	0.0408
	Model 2c: Model 1 + GXT duration	0.995	0.870, 1.137	0.9358
Body mass index (kg/m2) SD: 6.4 kg/m2	Model 1	1.080	0.973, 1.199	0.1492
	Model 2c: Model 1 + GXT duration	0.953	0.840, 1.082	0.4616
Lower 25th percentile of RMSSD (ms)
Graded exercise test duration (s) SD: 159 s	Model 1	0.675	0.588, 0.774	<0.0001
	Model 2a: Model 1 + WC	0.720	0.610, 0.852	0.0001
	Model 2b: Model 1 + BMI	0.658	0.557, 0.777	<0.0001
Waist circumference (cm) SD: 15 cm	Model 1	1.280	1.148, 1.428	<0.0001
	Model 2c: Model 1 + GXT duration	1.096	0.958, 1.253	0.1805
Body mass index (kg/m2) SD: 6.4 kg/m2	Model 1	1.164	1.048, 1.292	0.0044
	Model 2c: Model 1 + GXT duration	0.967	0.852, 1.098	0.6038

BMI, body mass index; CI, confidence interval; GXT, graded exercise test; OR, odds ratio; RMSSD, the square root of the mean value of the squares of differences between all successive RR intervals; SD, standard deviation; SDNN, standard deviation of all normal RR intervals; WC, waist circumference

Model 1: Adjusted for age, sex, race, study center, educational level, diabetes, hypertension, smoking status, use of β-blockers, and use of calcium channel blockers

Dependent variable: Lower 25^th percentile of HRV vs. upper 75^th percentile of HRV (referent)