Blood pressure behaviour during physical activity.

Abstract

Aerobic exercise is currently being recommended in addition to pharmacological therapy for lowering blood pressure levels in hypertensive patients, i.e. in subjects whose resting blood pressure levels exceed 145/90 mm Hg. On the other hand competitive sports are generally contraindicated in hypertensives, who are thought to be at increased risk of morbidity or mortality from their blood pressure levels. The present knowledge of blood pressure behaviour during isotonic physical activity is almost wholly based on the results obtained by means of the ergometric tests. Several maximal and submaximal exercise protocols have been introduced, but none has proved to be superior for diagnostic purposes. There is general agreement that the systolic blood pressure increase determined by isotonic exercise usually ranges from 50 to 70 mm Hg in both normotensive or hypertensive subjects. Diastolic blood pressure shows only minor changes in the normotensives, while in the hypertensives it tends to substantially increase because of their inability to adequately reduce their peripheral resistance. This mechanism may also explain the delay shown by the hypertensives in reaching pre-exercise blood pressure values during the recovery. On average diastolic blood pressure increases to a greater extent during bicycle ergometry than during treadmill, while no differences in exertional systolic blood pressure have been observed between the 2 tests. The results of several studies indicate that the blood pressure response to isotonic exercise is a marker for detection of hypertension earlier in the course of the disease, while resting blood pressure is still normal. According to some authors it is also of value in predicting future hypertension in individuals with borderline pressure levels. There are no conclusive data on the effect of training on blood pressure response to exercise. The majority of the published studies report small exertional pressure reductions after conditioning, which would merely reflect the reduction in resting blood pressure. Vasodilation greatly influences the exercise-induced rise in blood pressure; in fact the exertional pressor increase is blunted when the test is preceded by an adequate warm-up session. Isometric effort is thought to be contraindicated in hypertensive subjects, as it causes a pronounced increase not only of systolic but also of diastolic pressure. Mean blood pressure is, however, increased to the same extent by isotonic and isometric exercise, even though minor discrepancies have been reported by some authors.(ABSTRACT TRUNCATED AT 400 WORDS)