De-Stiffening the Aged Aorta with Regular Aerobic Exercise in Humans: Fact or Fallacy?

Background: Aortic stiffness, quantified by carotid-femoral pulse wave velocity (PWV), is a strong predictor of cardiovascular disease events. In general, dynamic "aerobic" exercise training performed regularly for many years in middle and older age is associated with an attenuated or absence of an age-related increase in aortic stiffness without hypertension. However, cross-sectional studies can be confounded by physiological or lifestyle factors that may contribute in part to the lower aortic stiffness observed, and prospective interventions are often limited by short duration and inadequate exercise frequency to have clinical benefit. Therefore, this review will discuss the evidence for the de-stiffening effects of regular, dynamic aerobic exercise training on aortic stiffness in the presence or absence of hypertension with some discussion on high-intensity interval training (HIIT). Summary: Short-term (3-12 months) aerobic exercise interventions, 2-3 days per week initiated in middle age or older age without hypertension, result in small decreases in carotid-femoral PWV that is likely the result of reductions in distending pressure (i.e., mean arterial pressure) rather than an alteration in structural wall properties. However, cross-sectional data indicate that 4-5 days/week appears to be the minimal frequency that is obligatory for de-stiffening of the aorta among adults who perform regular exercise in middle age and continue into older age. Despite greater improvements in aerobic fitness by high-intensity interval training (HIIT), short-term HIIT 4 days/week does not provide any benefit over moderate-intensity continuous training for de-stiffening the aorta among older adults with or without hypertension. Key Messages: Short-term aerobic exercise interventions 2-3 days/week at moderate intensity initiated in middle age or older age have small or no favorable blood pressure-independent effect on aortic wall stiffness. In contrast, 4-5 days/week appears to be the minimal obligatory dose of aerobic exercise to have some de-stiffening effects if performed during middle age and continuing into older age. Short-term HIIT provides no greater de-stiffening effects on the aged aorta than continuous aerobic exercise training.