Blood pressure (BP) and heart rate (HR) at rest and at the third minute of hand grip exercise (HG), body weight (W), height (H), body index (BI), triceps skinfold (TS), arm circumference (AC), and 24-hour excretion of Na, K, and creatinine were measured in two groups of 50 males 18 to 21 years of age. The subjects were divided in two groups depending on their physical activity. Group 1 included 50 trained subjects who had been regularly engaging in dynamic exercise for at least one month (four one-hour sessions a week); Group 2 included 50 untrained subjects. In Group 1 there was no significant correlation among systolic blood pressure (SBP) and anthropometric data at rest, but it was significantly correlated during HG with W, H, BI, and AC. In Group 2, SBP was significantly correlated only with W and BI at rest, with W, H, BI, and AC during HG. Diastolic blood pressure (DBP) was well correlated, both at rest and during HG, with anthropometric data in both groups studied. No correlation was found between BP and urinary excretion of electrolytes. The BP values appeared to be slightly lower in Group 1 than the ones in Group 2, both at rest and during HG (P less than .05). No significant difference was found in any of the other parameters considered. Our data seem to confirm that regular physical exercise may have a moderate lowering effect on BP both at rest and during exercise; this is independent of any concomitant weight loss.(ABSTRACT TRUNCATED AT 250 WORDS)