Mechanisms for the Benefits to Long Term Vascular Health Provided by Exercise
The vascular system responds favorably to exercise at any age. A large portion of the benefits of exercise derive from improvements to vascular function throughout the body, and physical fitness can be maintained further into old age than most people believe to be the case. The flip side of this point is that a sizable fraction of the declines of later life are a matter of disuse, people living a more sedentary life than is optimal for the health and function of muscles, heart, and brain. These the most energy-hungry tissues and those that see the worst outcomes from a decline in vascular function and consequently reduced delivery of nutrients and oxygen. Beyond the matter of blood supply, exercise is also protective against mechanisms involved in development of hypertension and atherosclerosis, as well as other conditions related to the vasculature. Overall, it is a good idea to maintain physical fitness for as long as possible in life, for these and other reasons.
Exercise-induced hemodynamic changes lead to mechanical stress of the vascular wall, the release of circulating growth factors from the endothelium, and the release of exerkines from the exercising skeletal muscle and other organs. These three main adaptive stimuli lead to an increased activity of several molecular pathways within the vascular endothelial and smooth muscle cells, culminating in a better vasodilation and vasoconstriction responsiveness, reduced arterial stiffness, arteriogenesis, and angiogenesis, higher antioxidative capacities, and reduced oxidative stress. Recent research revealed a potential role of enhanced mitochondrial biogenesis and mitophagy, substrate metabolism, and insulin sensitivity in the vascular smooth muscle cells for exercise-induced vascular adaptations.
Some vascular adaptations, such as a favorable balance of angiogenesis and angiostasis as well as of vasodilator and vasoconstrictor responsiveness, require regular exercise, ideally throughout the entire life span. Therefore, individualization of exercise according to objective and subjective factors should be sought to achieve the best possible long-term training adherence. Repeated stimuli, at least every other day at initial stages and progressively increasing to 5-7 days per week, might be necessary to use the full potential of favorable physiological alterations, such as elevated blood pressure and improved glycemic control, which last for about 24 hours post exercise.
The cumulative volume of elevated shear stress seems more important than peak shear stress in terms of stimulating vascular remodeling. Thus, prolonged moderate-intensity workouts may be favored over shorter sessions with very high intensities, especially if injury prevention and long-term training adherence are important. High-intensity interval training may have additional benefits in the long-term, such as increased antioxidative and metabolic capacities, and thus should also be part of vascular exercise training. Resistance and aerobic exercise induce distinct macro- and microvascular adaptations; thus, both types of exercise should be implemented in comprehensive training for optimal vascular health.