Circulating B-type natriuretic peptide (BNP) has been used as a marker of left ventricular hypertrophy and heart failure, and known to be increased after exercise in healthy men as well as patients with left ventricular dysfunction. However, the relationship between exercise duration and BNP level, and the determinants of circulating BNP concentration during exercise have not been fully elucidated. For these reason, we measured circulating BNP level during exercise, and exercise-induced changes of cardiac function by echocardiography in healthy men.

Ten healthy male volunteers (mean age 27±3 year-old) underwent symptom-limited bicycle ergometer in supine position for 30 min. The workload started at 25 W for 6 min with increment of 50 W every 3 min. Blood samples for BNP were obtained at baseline, every 1 min for first 3 min, 25 W, 75 W, 125 W, peak exercise and 10 min after resting.

BNP level was increased only at peak exercise (mean:5.3±0.5 vs 7.7±4.1 pg/ml, median:5.0 vs 6.3 pg/ml, p<0.05), not during submaximal exercise, and sustained 10 minutes after exercise (190±25 watt, 14.9±12 min). Peak BNP level was significantly correlated with baseline BNP level (r=0.723, p<0.05), E' (0.18±0.04 vs 0.29±0.08 m/sec, r=-0.649, p<0.05) and E/E' (4.18± 0.87 vs 5.66±2.31, r=0.769 p<0.01) by bivariate correlation analysis, but correlated with only baseline BNP level by multiple linear regression analysis (p<0.05).

Circulating BNP concentration was minimally increased only after peak exercise in young healthy men, not increased at submaximal exercise The BNP concentration after exercise is only determined by baseline BNP level, not by duration and workload of exercise.