CARDIOVASCULAR COMPONENTS
The cardiovascular system is comprised of central and peripheral systems. The central system is the heart; key hardware delivering blood from the heart to the lungs for oxygenation and waster removal then back to the heart ready for delivery into the periphery.
Equally important is the peripheral system, the network of blood vessels throughout the entire body. The peripheral components of the body are the limiting components of performance. The peripheral system is comprised of the arterial and venous circuits as well as capillary networks.
The arterial circuit is comprised of blood vessels known as arteries. Arteries carry oxygenated blood from the heart to the periphery. Arteries have thick, compliant walls to accommodate large and dramatic changes in blood flow where maintain blood pressure is vital. The characteristics of arteries are they appear red in colour, carrying oxygenated blood.
The venous circuit is named so as the blood vessels are called veins. Veins carry different architecture to arteries. They have thinner wall thickness. To reduce TPR in the arterial circuit and maintain positive single direction flow, veins have valves to prevent blood flowing backwards due to gravity or when the peripheral pump operates. Veins appear blue in colour as oxygen has been removed from the red blood cells.
Connecting the arterial and venous circuits are capillary networks enabling the transfer of oxygen and removal of waste. As blood flows through the arterial circuit it moves into the capillary networks that perfuse the muscles of the body. Capillaries are extremely thin, single cell thickness, blood vessels. As blood travels through the capillary networks, oxygen and fuel is drawn from the blood and can be replaced with waste products from cell metabolism. The blood continues to pass through the capillaries which empty into the venous circuit.
Individuals with greater capillary development have larger aerobic power delivering more blood flow to the working muscles with reduced resistance. Appropriate aerobic and recovery training are the key promoters of enhancing capillary networks.
The arterial and venous circuits are limited and training has little to no effect on changing or improving them. Both circuits are developed and complete by birth. The greatest area of improvement in the peripheral and indeed the entire cardiovascular system is in the capillary networks.
There is no limitation on capillaries; they develop directly in response to the repeated stimulus and requirement for more blood flow. Effective coaching and training of the aerobic training has a positive response on these adaptations.
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