Blood pressure response to exercise of obese and lean hypertensive and normotensive male adolescents

Abstract

Blood pressure response to exercise was studied in 100 male adolescents with essential hypertension, aged 13-18 years, during progressive maximal exercise test (Bruce Protocol). None received medication. Thirty of the subjects were obese hypertensive (OH), 30 were lean hypertensive (LH), 10 were obese normotensive (ON) and 30 were lean normotensive (LN). Quatelet index was used to measure obesity. Blood pressure was measured at rest and during treadmill test. Systolic blood pressure (SBP) values at rest showed a statistically significant difference between the hypertension and control groups (P < 0.0001), but not between the OH and the LH. During moderate exercise (stage II Bruce), however, this difference was significant (P < 0.0001). SBP > or = 160 mm Hg separated the hypertensives from the normotensives, with a sensitivity of 86.7%, specificity of 85.0% and positive predictive value of 89.7%. During maximal exercise, the difference between values of OH and LH was also significant (P < 0.001). Approximately one third of the obese adolescents had SBP > 220 mm Hg, in maximal exercise. Heart rate response to exercise was greater in the ON group than in the LN. The findings suggest that: (1) obese hypertensive adolescents have higher blood pressures than lean hypertensives during exercise, indicating a more pathophysiological derangement in them; (2) the treadmill test discloses mechanisms, different than those at rest, which induce blood pressure elevation with exercise; and (3) moderate exercise identifies the hypertensive subjects.