What Is Aerobic & Anaerobic Metabolism?
By Christine St. Laurent
, last updated March 19, 2012
Metabolism is a process that takes place in the cells of your body to convert your food sources into energy. The two main systems of metabolism are aerobic and anaerobic. Both involve a series of steps in which your food is transformed from its storage state to your body's source of energy. Aerobic metabolism requires oxygen to be present. Anaerobic metabolism occurs without the use of oxygen.
Anaerobic: Without Oxygen
Anaerobic metabolism is responsible for creating energy for your movements without the use of oxygen. It takes a minute or two for your body's cardiorespiratory functions to kick in when you start exercising in order to transport oxygen that you breathe in throughout your body. During this time, you rely a little more on anaerobic metabolism for energy. Activities that are high in intensity or near maximal levels and last up to two minutes use your anaerobic system. Examples of anaerobic activities are sprinting, cycling up a steep hill and heavy weightlifting. With these exercises you either need to slow down to keep going or lactic acid will build up, creating that burning sensation in your muscles, and force you to stop. Stored forms of carbohydrates are the fuel source for anaerobic metabolism.
Aerobic: With Oxygen
Aerobic metabolism uses oxygen to create energy from carbohydrates, fats and even protein. Protein typically is not a major energy source, but it can be when your body does not have enough carbohydrates or fats stored, such as in a state of starvation. Aerobic metabolism is the main system used after two minutes of exercise. During a workout, both systems can be put to work depending on your intensity level and duration.
To train your aerobic system, include exercise sessions of longer durations at a moderate intensity level. For example, walking or running on a treadmill for 30 minutes at a pace that makes you feel a little winded will engage your aerobic metabolism. You can vary the intensity during this workout, but to keep it aerobic in nature you want to stay below your anaerobic threshold. This threshold is often described as the point where you start to feel a burn in your muscles.
Because anaerobic metabolism will max out in a minute or two of an all-out effort, you'll need to use interval training to target this system. Alternating bouts of higher effort with recovery, or easier segments, is an effective method. You can increase the intensity of an exercise by speeding up your pace, using an inclined surface, making larger movements or by adding a jumping action.