There are two main types of exercise – anaerobic and aerobic.Because they utilize different energy systems the body, their physical benefits differ.Every movement that your muscles make draws on reserves of energy.In order to meet this demand, your body must continually replenish the energy stores of the muscles.Energy can be supplied to the muscles using one or more of three systems:the phosphocreatine, the lactic acid, or the aerobic.Which one comes into play depends on the intensity and duration of the exercise being undertaken.Highly exertive exercise performed for three minutes or less – sprinting, for example, demands that your body use the first two forms of energy production, the phosphocreatine and the lactic acid, neither of which requires oxygen.Together they are known as the anaerobic (without oxygen) systems.The blood cannot supply oxygen fast enough for the aerobic system to operate.Low-intensity exercise that lasts for more than three minutes draws on a form of energy production involving oxygen.This is the aerobic (with oxygen) system.Oxygen can be supplied fast enough for the aerobic system to work.When your muscles are at rest, even though they are never totally inactive, their energy reserves are topped up at a steady rate from all three systems.
