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Aerobic Based Exercise

The aerobic process consumes fuel in the presence of oxygen (supplied by the flow of blood) producing by-products, carbon dioxide and water, which are expelled by respiration and perspiration. The aerobic process provides the majority of the energy used by the slow acting muscle fibers (crucial to endurance activities). 

At lower intensities the body uses a mixture of fat and carbohydrate as its source of fuel. If the exercise objective is weight loss, it is necessary to burn as much fat (as opposed to carbohydrate) as the source of fuel as possible. This is best achieved at lower intensities and over longer durations. As soon as the intensity is increased the aerobic process starts to burn more carbohydrate and the fat loss effect will be reduced. A low intensity (60 - 70% of the maximal aerobic output) is typically that at which you can hold a conversation: it is by no means strenuous and is about that achieved by a brisk walk.

If the exercise objective is aerobic (cardio-vascular/endurance) training then it is necessary to exercise at an intensity which will avoid fatigue due to lactate build up. This is best achieved at moderate levels of intensity over medium/long durations. 

At about 70 - 80% of the maximal aerobic output, lactate begins to accumulate in the blood supply at a greater rate than it can be extracted by the liver, kidneys and other organs. Exercising above this intensity will cause progressive accumulation of lactate in the blood, increased heart and breathing rates, muscle fatigue and, eventually, the cessation of exercise. Prolonged exercise at or below this intensity will maintain lactate at non-fatiguing levels and exercise duration will be limited solely by the depletion of available fuel stores.

A sustained exercise program of aerobic conditioning will improve the efficiency with which the respiratory and cardiovascular system can supply oxygen. This improves lung function, heart function, vascular efficiency and capillary growth, leading to improved well being and endurance.