Introduction 5 11 12 13 15 1 8 15 2 3 10 Methods and statistical analysis 6 14 10 14 n p 4 n n n n n P Results 1 Table 1 Baseline characteristics according to tertiles of 2-minute heart rate recovery (N = 2,648)a Baseline Baseline sex-specific HRR tertiles 1 (slow) 2 3 (fast) P trend Number of women 479 463 521 NA Number of men 392 391 402 NA HRR (median [min, max]) Women 31.0 (1.0, 36.0) 41.0 (37.0, 45.0) 51.0 (46.0, 116.0) NA Men 34.0 (−6.0, 39.0) 44.0 (40.0, 48.0) 54.0 (49.0, 97.0) NA Age (years) 25.4 (3.5) 25.1 (3.6) 25.0 (3.6) 0.003 N 360 (41.3) 383 (44.9) 435 (47.1) 0.014 2 24.9 (5.2) 24.1 (4.2) 23.8 (4.0) <0.001 Resting heart rate (bpm) at year 0 71.5 (11.4) 69.3 (10.2) 66.1 (9.7) <0.001 Resting heart rate (bpm) at year 15 68.3 (10.8) 68.2 (12.1) 66.5 (11.3) <0.001 Maximum heart rate (bpm) 180.1 (15.8) 180.0 (14.6) 181.0 (13.9) 0.001 Estimated METs at peak exercise 11.8 (3.0) 12.1 (2.7) 12.5 (2.7) <0.001 Total physical activity score (exercise units) at year 0 375.8 (273.0) 428.6 (317.5) 459.7 (307.3) <0.001 Total physical activity score (exercise units) at year 15 325.4 (278.1) 346.9 (288.0) 382.4 (296.6) <0.001 a n 2 Table 2 Unadjusted odds ratio (95% confidence interval) for the presence of coronary artery calcium (score >0) at year 15 by baseline 2-minute heart rate recovery  Total sample Caucasian men Caucasian women African-American men African-American women Odds Ratio (95% CI) for threshold models based on HRR tertiles Tertile 1 (slow) 1.13 (0.81–1.57) 0.90 (0.54–1.50) 1.12 (0.53–2.33) 1.11 (0.52–2.36) 1.44 (0.60–3.49) Tertile 2 1.20 (0.87–1.66) 0.90 (0.54–1.50) 0.90 (0.41–2.01) 1.55 (0.78–3.09) 1.37 (0.57–3.32) Tertile 3 (fast) 1.00 (Ref) 1.00 (Ref) 1.00 (Ref) 1.00 (Ref) 1.00 (Ref) Odds Ratio (95% CI) for HRR as continuous variable a 0.99 (0.87–1.13) 1.04 (0.84–1.28) 0.86 (0.65–1.15) 0.95 (0.70–1.30) 0.88 (0.60–1.27) a n Conclusion Slower HRR in young adulthood is not associated with the presence of CAC when assessed 15 years later in middle age (average age 40 years). Moreover, mean HRR at baseline did not differ between those with and without measurable CAC at year 15. While previous studies have examined the relationship of HRR with CAD events this study is first to investigate the relationship of HRR with a measure of subclinical atherosclerosis. 5 12 2 3 10 9 7