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The development of performance in competition is achieved through a training process that is designed to induce automation of motor skills and enhance structural and metabolic functions. Training also promotes self confidence and a tolerance for higher training levels and competition.

Cardiovascular System

The Heart
Cardiac Output is the amount of blood that the heart pumps in a given period of time. It is determined by the heart rate and stroke volume. As an athlete trains and gets fitter, the stroke volume usually gets larger. That is, with each beat the heart forces more blood out and of course, with it more oxygen to the working muscles. Easy steady training is the best type for desirable cardiovascular adaptations with the least discomfort. There will be more time training if the intensity isn’t too great.

Maximal Heart Rate
This is the maximum number of beats per minute that the athletes’ heart can attain. This is dependent on the athletes’ age and type of exercise. For a man this is predicted as 220 minus his age and for a woman, 205 minus half their age. However, these formulae are only a prediction and will vary on an individual basis. Maximum heart rate(which is dependent on age in most cases) that a triathlete can reach does not vary too much with training but heart rates at lower intensity will gradually reduce as the athlete gets fitter and stroke volume improves.

Maximal Oxygen Uptake
Is the maximum amount of oxygen that can be consumed by the body during exhausting exercise. Physiologically, it is the product of the amount of blood pumped by the heart (cardiac output) and the amount of oxygen taken from the blood as it passes through the body tissues, in particular, working muscles. The amount of oxygen used is measured as the difference in the oxygen content of arterial and venous blood. This is known as the arterio-venous oxygen difference. Maximal oxygen uptake is also called Vo2 Max.

Oxygen Carrying Capacity of the Blood
The amount of oxygen that blood can carry is expressed in millimeters of oxygen carried per 100 millimeters of blood and is a function of the hemoglobin concentration of the blood. Each gram of hemoglobin can transport 1.34 milliliters of oxygen.
Factors that can affect oxygen carrying capacity of the blood can be diet(low in iron) and altitude (which can lower the saturation rate of oxygen in the blood because of the partial pressure difference).

Blood flow is determined by the diameter of the vessel through which the blood moves, the pressure difference between the heart and the destination of the blood, and the viscosity or thickness of the blood.
The viscosity of the blood stays relatively constant but when exercise commences, the most desirable situation is for the vessels feeding the exercising muscles to relax and open up, which decreases the pressure in that area. This increases the pressure difference between the source of the blood and its destination. The fact that the heart is beating faster and harder with increased pressure adds to the pressure difference. The greater this pressure difference between the heart and the working muscles allows a stronger flow of blood/oxygen.
As well, blood flow to the working muscles increases as a result of a diversion of blood from areas of lesser need, such as organs of digestion.