Abstract

BACKGROUND: It is claimed that exaggerated blood pressure (BP) reactivityto behavioral stress may play a role in hypertension. This study aimed to clarify whether exaggeratedBP reactivity during physical exercise is associated with any other abnormalities in ambulatory BP, autonomicnervous control, and target organ damage among middle-aged normotensive men. MATERIAL/METHODS: A totalof 54 sedentary men (39+/-4 years old) with normal BP were enrolled in this study. Twenty-seven withexaggerated BP reactivity to exercise (ER) were compared with 27 age-matched controls with normal BPreactivity (NR). The subjects underwent 24-hour ambulatory BP monitoring, short-term Finapres recordings,a bicycle ergometry test, and M-mode and pulsed-Doppler echocardiography. RESULTS: The ambulatory BPmeasurements were significantly higher in the ER group than in the NR group averaged over a 24-hour period,during daytime and nighttime. Power spectral analysis from continuous Finapres data revealed increasedsystolic BP variability in the low frequency band in the ER group. During graded exercise, the ER groupshowed remarkable elevations in systolic and diastolic BP compared to the NR group without a differencein heart rate increments. Although the plasma epinephrine showed similar levels, yet the exercise-inducedincrease in plasma norepinephrine in the ER group was significantly greater than in the NR group. Inechocardiographic dimensions, left ventricular internal diameter and mass index were not different, whereasthe ER group presented significantly greater posterior wall thickness. Doppler functional data showedsignificant increase in the late to early flow velocity ratio in the ER group. CONCLUSIONS: Even in theabsence of hypertension, exaggerated BP reactivity to physical exercise suggests greater BP elevationduring daily activity as well as enhanced sympathetic nervous tonus, which may be considered a risk factorpromoting hypertension, and these hemodynamic and neurohumoral behaviors are associated with a tendencyto develop target organ abnormalities in the heart.

Keywords: Cross-Sectional Studies, Blood Pressure, Echocardiography, Exercise - physiology, Exercise Test, Heart Ventricles - anatomy & histology, Sympathetic Nervous System - physiology, Ventricular Function