How does Aerobic Respiration work during exercise?

After two minutes of exercise, the body works to supply muscles with oxygen. In the presence of oxygen, glucose is completely broken down into carbon dioxide and water. This process is called aerobic respiration.

Glucose comes from three different places:

  • the glycogen supplies that remain in muscles
  • theliver's glycogen which is broken into glucose, carried to working muscle through the bloodstream
  • glucose absorbed from food in the intestine, carried to working muscle through the bloodstream

Fatty acids from fat reserves in muscle and other parts of the body are also used by Aerobic respiration to produce ATP. (Adenosine triphosphate, or ATP, is the way your body uses biochemicals to store and use energy.) In extreme cases (such as starvation), proteins are broken down into amino acids and used to make ATP. Aerobic respiration first uses carbohydrates, then fats and finally proteins, when necessary. Aerobic respiration uses more chemical reactions to produce ATP than either the Phosphagen System or the Glycogen-Lactic Acid System.

The slowest rate of the three systems is aerobic respiration, but it continues to supply ATP for several hours or longer if the fuel supply lasts.

Energy is also produced by the Phosphagen System and the Glycogen-Lactic Acid System.

Joanne Duncan-Carnesciali, CPT,NASM Elite Trainer
Physical Medicine & Rehabilitation
Aerobic respiration in a nutshell is the body's ability to transport oxygen into the mitochondria of the cell and produce a very important energy source that is required for muscular contraction called ATP.

During exercise, if oxygen is not transported to the cells quickly enough, one tires out rather quickly because it can't produce the ATP.  It's sort of like your cells running out of gas. You might have experienced this if you ran with all your might up a flight of stairs or towards a bus and felt a burning sensation in your legs.  Perhaps you had to stop to catch your breath.  The intensity or how hard you exerted yourself while performing that intense bout of activity had everything to do with whether or not sufficient oxygen was able to be transported to the mitochondria of all your cells to produce that all important ATP needed in order for your muscles to contract.  If no oxygen is taken in at the cellular level no ATP production, no muscle contraction.

On the otherhand if you perform exercise at the right intensity for your fitness level your body will be able to carry oxygen into by mitrochondria to produce ATP so that you are able to perform continuous exercise over a prolonged period of time.  So if oxygen is transported to the mitrochondra, ATP is produced and the muscle contracts.

To better visualize this imagine how a cyclist or a long distance runner must train at the right intensity so that he/she can cycle or run for hours.   The intensity of the cyclist or runner is such that oxygen gets to the mitochondria, ATP is produced and the necessary muscular contraction occurs.

Hope this answers your question.

Aerobic respiration is simply breathing. When you exercise, your breathing rate increases to compensate for the increased need of oxygen that is required by your muscles. When you exhale, you expel carbon dioxide, the by-product of used oxygen.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.