His heart rate is increasing as well as his breathe per minutes. At his age, excitement is very much increased and is there for increasing also the cardiovascular activity. The cardiovascular system helps transport oxygen and nutrients to tissues, transport carbon dioxide and other metabolites to the lungs and kidneys, and distribute hormones throughout the body. The cardiovascular system also assists with thermoregulation. The runner's sympathetic nervous system is activated (central command), and catecholamines are released from the adrenal medulla. This is the reason in cardiac acceleration, increased myocardial contractility, increased cardiac output, peripheral vasoconstriction, and an increase in blood pressure.
As the race started the following factors in the cardiovascular system are considered: the heart rate, peripheral resistance, skin blood flow, cardiac output, and blood flow distribution. Cardiovascular changes at the start of the game include the compression of the blood vessels in the contracting muscle leading to a reduction in the blood flow. Heart rate continues to increase during the race, until the rate reaches a plateau of about 180 beats/min at maximum effort. Peripheral resistance decreases because of relaxation of arterioles in active muscle and skin (as body temperature rises). Skin blood flow increases, which aids in heat loss. Blood flow to inactive muscle, kidney, and gastrointestinal tract is reduced. Because BP is a major determinant of afterload, the left ventricular wall stress, and thus the cardiac workload, is significantly higher. As the intensity of the race increases the BP is also increasing from 120 mmHg to approximately 200 mmHg. Maximum oxygen uptake level (VO2max) is reached during this state. Cardiac output increases during the race until 40% of VO2max (maximum oxygen uptake level) is reached. Cardiac output rises from approximately 80 mL/beat to approximately 120 mL/beat. HR increases with intensity until VO2max is reached. HR rises from approximately 70 beats per minute to approximately 200 beats per minute. Cardiac output increases with intensity until VO2max is reached. Cardiac output rises from approximately 5 L/min to approximately 25-30 L/min. (Suleman, 2006).
The race is almost over the athletes are chasing to cross the finish line first. There is an increase in PaCO2 in the Kenyan athlete. PACO2 represents the amount of CO2 in solution. When there is an increase in blood PACO2, there is an increase in ventilation. During this stage more oxygen is needed and more CO2 and metabolic acid are produced. There is an increased cardiac output because the tissues need more oxygen supplied to them. This is also caused due to an increase of lung ventilation to support gas tensions in arterial blood, which experiences faster blood flow. When an individual is on the move, the venous blood shows signs of decreased O2 levels, increased CO2 levels, and an increase in H+ levels.
During the race the blood flow to the leg muscles increases because of the local factors, which includes: the release of vasodilator metabolites (e.g. adenosine); the increase in muscle temperature; and the local decreased in pH (increased CO2 and lactic acid). The arterioles dilate and more capillaries open (capillary recruitment). Venous return is facilitated in running by the following: sympathetic-mediated contraction of capacitance vessels ; muscle compression of the leg veins with one-way