Aerobic Metabolism and Exercise

How the Body Produces Energy Aerobically

Aerobic Workout on the Treadmill
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Aerobic metabolism is the way your body create energy through the combustion of carbohydrates, amino acids and fats in the presence of oxygen. Combustion means burning, which is why this is called burning sugars, fats, and proteins for energy. Aerobic metabolism is used for sustained production of energy for exercise and other body functions.

The Details of Aerobic Metabolism

In the aerobic metabolic process, the human body uses a molecule of glucose to produce 36 adenosine triphosphate (ATP) molecules.

ATP is what fuels your muscles. Anaerobic metabolism, which is used for vigorous muscle contraction, only produces 2 ATP molecules per glucose molecule, so it is much less efficient.

Aerobic metabolism is part of cellular respiration and involves your cells making energy through glycolysis, the citric acid cycle, and electron transport/oxidative phosphorylation. For details about the chemistry involved, see how the body produces energy for exercise.

How Your Body Uses Aerobic Metabolism

The body uses aerobic metabolism for energy throughout the day to fuel regular activity by the cells, muscles, and organs. This is why you have a basal metabolic rate, a level of calorie-burning needed just to maintain the normal body functions, apart from physical activity calories burned. A living body is always burning some calories, even at rest.

Aerobic metabolism is also why your lungs absorb oxygen to be carried by hemoglobin in the blood to your tissues.

The oxygen is used in aerobic metabolism to oxidize carbohydrates and the oxygen atoms end up attached to carbon in the carbon dioxide molecule that is excreted.

The only byproducts of the process of aerobic metabolism of carbohydrates are carbon dioxide and water. Your body disposes of these byproducts by breathing, sweating and urinating.

Compared with anaerobic metabolism, which produces lactic acid as well, aerobic metabolism produces byproducts that are easier to remove from the body.

Why Do You Want to Use Aerobic Metabolism in Exercise?

An aerobic exercise is done at a heart rate below 85 percent of maximum heart rate and doesn't use vigorous muscle contractions. Your body is able to maintain a constant energy stream by breaking down carbohydrates and fats with aerobic metabolic processes.

During exercise, using aerobic metabolism for energy results in less muscle soreness afterward than occurs with anaerobic metabolism. It is the cleaner-burning process without byproducts that lead to soreness. Anaerobic metabolism results in producing lactic acid. You feel burning and fatigue quickly as it builds up in a muscle being contracted in strength training. It also leads to delayed onset muscle soreness, the aches you feel the next day. Strength training, jumping, and sprinting are typical forms of exercise that use anaerobic metabolic processes.

At a moderate-intensity level of exercise, you are breathing enough and your muscles' need for ATP is slow and steady enough that you can break down glycogen into glucose and mobilize stored fat to break down for energy.

You can also take in carbohydrate that the body can use before all of the stores are depleted. Athletes who get this wrong experience bonking or "hitting the wall."

You can achieve the aerobic exercise zone by walking at a brisk pace where you may be breathing a little hard but still able to speak in full sentences. If you are ready to put aerobic metabolism into action, enjoy this aerobic walking workout.

Walking uses aerobic metabolism to burn sugars and fats. Be sure to bring along walking snacks on any endurance walks of two hours or more so you can replenish the energy you need to keep going.

Weight Loss and Aerobic Metabolism

If your goal is to lose weight through exercise, aerobic metabolism is your friend as it takes fat out of the fat cells and burns it to produce energy for the muscles. It also burns up the available and stored sugars (carbohydrates) in your cells, so any excess won't be processed into fat. The food that you eat will replenish your available energy stores. If you don't eat more calories than you burn off, you won't store extra food calories as fat. But you also must remember that exercise will build muscle, so while losing fat you may also be gaining muscle mass.