Habitual exercise and blood pressure: age dependency and underlying mechanisms.

Background: Regular exercise is associated with a reduction in cardiovascular risk, but the precise mechanisms responsible are unknown. The aim of the current study was to examine the relationship between regular exercise, aortic stiffness, and wave reflections, and to determine whether this relationship differs by age.

Methods: Younger (<30 years) and older (>50 years) individuals, who were either sedentary or undertook regular aerobic exercise, were drawn from the Anglo-Cardiff Collaborative Trial population. This yielded 1,036 individuals, all of whom were nonsmokers, and were free of cardiovascular disease and medication. All individuals undertook a detailed lifestyle and medical history questionnaire including details of physical activity. Brachial and central blood pressure, together with aortic stiffness, wave reflections, cardiac output, and peripheral vascular resistance were assessed in all individuals.

Results: In younger individuals, regular exercise was associated with lower diastolic blood pressure but elevated pulse pressure. In contrast, both systolic and pulse pressure were lower in older active individuals, compared with their sedentary counterparts. Moreover, regular exercise was associated with lower wave reflections and peripheral vascular resistance in younger individuals, but lower large artery stiffness in older individuals.

Conclusions: These data suggest that regular exercise is associated with a beneficial vascular profile. However, this differs between younger and older individuals such that the smaller preresistance and resistance vessels are involved in younger individuals whereas the large elastic arteries are involved in older individuals. Despite these differential findings, the current data provide support for strategies that increase habitual physical activity levels in the general population.