Pathophysiology of exercise hypertension.

The blood pressure is not a fixed entity but rather a parameter subject to substantial situational fluctuations. Studies based on ambulatory blood pressure measurement as well as exercise testing have shown that the highest blood pressure values in an individual can be recorded during physical exercise. During exercise in healthy subjects, in association with an increase in cardiac output and decrease in peripheral resistance, there is an increase in systolic arterial pressure with nearly constant diastolic pressure. In contrast to normotensive individuals, during dynamic exercise hypertensive patients demonstrate excessive pressure increases due to impaired vasodilatation. The mechanism responsible may be structural changes in the arteriolar walls but age is also an important determinant. The extent of blood pressure increase is more dependent on the mass of contracting muscle than on the mode of contraction. During isometric exercise, there is an increase in both systolic and diastolic blood pressure, predominantly reflex-induced, which is more marked in patients with manifest hypertension at rest than in those with borderline hypertension or in normotensive subjects. During dynamic exercise in a subgroup of patients with coronary artery disease, in contrast to normal subjects in whom the diastolic pressure remains constant, an increase in up to 15 mm Hg in this parameter may be found as a result of ischemia induction with left ventricular dysfunction, inadequately increased cardiac output and reflex vasoconstriction. During dynamic exercise, there is an increase in norepinephrine, more marked in hypertensive than normotensive subjects together with an increase in plasma renin activity; plasma aldosterone changes are in parallel with those of renin activity.(ABSTRACT TRUNCATED AT 250 WORDS)