Exercise Response in Young Women with Borderline Hypertension: DISCUSSION

31 Mar

Exercise Response

A group of 157 young women with BH was found to have higher levels of systolic and diastolic blood pressure at all stages of dynamic exercise compared with values in normotensive controls. However, the systolic and diastolic blood pressure changes in the BH patients resembled the normal response found in the controls. The data on exercise testing in young women with high resting blood pressure are limited: most studies describe children or adolescents, either males only or mixed groups of boys and girls. Hansen et al found that blood pressure change during exercise did not differ in normotensive girls compared with hypertensive girls. Other studies of blood pres­sure response to exercise in young populations of both sexes did not reveal a uniform pattern of blood pressure change. This variation in results may be attributed to several factors, such as personal characteristics or the definition of hypertension. Sex variabilities in blood pressure values, both at rest and on effort, probably also play an important role. Normotensive women had lower blood pressure on ambulatory measurement using an automatic device; normoten­sive and hypertensive women showed a lower increase in blood pressure and heart rate during isometric exercise. These differences were attributed to envi­ronmental, hormonal, or behavioral parameters, and it is accepted that sympathetic activity is a major element in determining blood pressure levels. Hyper­tensive women were found to have lower catechola­mine levels than men and to have a smaller increase of catecholamines during mental stress, head-up tilt, and isometric exercise. Whether this response to various stimuli is related to different modes of secre­tion of catecholamines or to different clearance rates of catecholamines remains to be clarified. Another frequently mentioned factor is the inotropic action of estrogens that may play a role in the varying blood pressure response of females compared with males. It has recently been suggested that exercise blood pres­sure might be more accurate as a predictor of hyper­tension than resting blood pressure, and may also serve in identifying subjects with sustained hyperten­sion that will, in all probability, have developed by long-term follow-up.

The present data on young women resemble our previously reported study of young borderline hyper­tensive men. They are also in accord with the “classic” studies on exercise response in male patients with borderline hypertension, showing that blood pressure response to dynamic exercise in the young patients resembles that seen in normal subjects. We postulate that the set-up point of blood pressure in both male and female hypertensive subjects is higher compared with normotensive subjects, but the response to exercise parallels that demonstrated by normotensive subjects. Thus, neither one of the groups differs in systolic or diastolic blood pressure change, or in pulse pressure change, from rest to exercise. Exercise testing did not contribute significantly to the information already established by repeated measure­ments of resting blood pressure. Benbassat and Froom, in reviewing this field of study, stated that the published data do not justify routine exercise testing for screening purposes, and that exercise testing as a predictor of hypertension needs further experimental development and confirmation.
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Nonspecific ST and T wave changes at rest and at exercise test were significantly more common in our BH patients than in the controls; mean QTC was significantly longer. These findings possibly reflect autonomic nervous system imbalance, the exis­tence of which is indicated by the hyperkinetic circu­lation at rest and exercise in our BH patients.

In conclusion, our study does not support the view that the assessment of blood pressure during ergometry is useful in distinguishing between normoten­sive and hypertensive subjects. The role of exercise blood pressure as a predictor of hypertension in young females requires considerably broader investigation and elucidation.