Our bodies are complex but very efficient machines.  In a recent article in Healthology it has been described as 3 engines.  The first one providing us with bursts of energy we need for weight training.  This engine runs on protein and does not require oxygen, and therefore is anaerobic. The second one is for half marathons and runs on glucose and also does not require oxygen and therefore is also anaerobic.  The third engine is for running long distances and runs on carbohydrate glycogen and requires oxygen to produce energy; therefore, it is aerobic.

This third engine takes a long time to get started and requires a lot of energy, but provides amazing benefits because of this.  If your goals are to lose weight, reduce risks of heart disease and strokes, increase stamina, help with diabetes, improve overall mood and energy levels, this third engine needs to be working well.

It’s important to assess your current level of fitness before starting an aerobic exercise regime.  If you are currently not doing any exercise, you should start with a low intensity routine such as walking or light jogs. However, if you are exercising already and simply want to increase your level of fitness, you should increase the time you train, within your current workout schedule but maybe reduce the number of days you train to ensure you don't over exert your muscles or injure yourself.

It is highly suggested that you monitor your heart rate with aerobic exercise because it is your heart that needs to work hard in order to provide the energy for your body. The article likens it to a weight trainer not knowing the weight he is lifting.  So you need to know what your heart is doing in order to understand how hard you are pushing yourself in aerobic exercise.

You can look for target heart rates at varies sites, but remember to talk to an expert about your workout program for your specific fitness level.