Previous studies have pointed out that exaggerated blood pressure (BP) response during physical exercise could be an early marker of essential hypertension. Apparently some of the exaggerated BP responders present changes in the heart geometry and function that are usually found in the early course of the hypertensive disease. To evaluate the association between exaggerated BP response and these changes, we submitted 20 normotensive men presenting elevated BP response during bicycle exercise (hyperreactive group, systolic BP > or = 220 mmHg at maximal workload) to 24-h ambulatory blood pressure monitoring (ABPM) and to two-dimensionally guided M-mode echocardiography and pulsed Doppler. The results from this group were contrasted with those of a comparable group, which otherwise, presented normal BP response during the same procedure (control group, systolic BP < or = 210 mmHg at maximal workload). The ABPM measurements were normal and analogous between the two groups: the mean 24-h systolic blood pressure (SBP) was respectively 126 +/- 6 mmHg and 129 +/- 5 mmHg, diastolic blood pressure (DBP) 82 +/- 4 mmHg in both groups, and heart rate (HR), respectively 76 +/- 9 and 74 +/- 7 bpm. The univariate correlation (R) between the maximal BP response during bicycle exercise and BP measurements in the ABPM were in general weak, and as a whole, the hyperreactive group presented the weakest correlation coefficients. M-mode echocardiographic data such as the left ventricular mass index (LVMI, 80 +/- 10 vs. 81 +/- 11 g/m2), posterior wall and interventricular septal thickness (PWT, 8.8 +/- 0.6 vs. 8.6 +/- 0.7 mm; IVST, 9.0 +/- 0.4 vs. 8.8 +/- 0.6) were also normal and comparable between the groups. LV systolic functional indexes such as fractional shortening (LVFS, 39 +/- 2.8 vs. 40 +/- 3.5%) and ejection fraction (LVEF, 70 +/- 3.5 vs. 71 +/- 3.7%) were also normal and similar. Doppler-derived LV diastolic functional indexes such as the peak velocity of early flow divided by the peak velocity of late flow (RE/A) and isovolumetric relaxation time (IVRT) were also equivalent (RE/A, both 1.3 +/- 0.2, IVRT 79 +/- 7 vs. 81 +/- 6 msec). These results support the concept that an exaggerated BP elevation during physical activity, when not accompanied of higher levels of BP during daily activities are not associated with changes in the heart geometry or in the ventricular function, and might represent an hemodynamical behavior of limited pathological and clinical importance. These conclusions must be taken cautiously since personal characteristics such as life style, family history of hypertension, gender, race and also the levels of BP chosen to delimit a normal and an exaggerated BP response might be important factors determining the consequences of the hyperreactive behavior.